Climate Change Effects
on Natural Resources
FOR 797, Fall 2007
John Stella, stella@esf.edu
This seminar examined the evidence of
global climate change, integrating
scientific analyses and their perceptions in
the media. Weekly class discussions
focused on different physical, biological,
and social facets of the climate change
story. Readings were drawn from primary
climate change research (Nature,
Science), global and regional analyses
(IPCC 4th Assessment Report, New
England Regional Assessment), news
accounts, and the popular science
literature (e.g. Tim Flannery’s The
Weather Makers).
For the final ‘White Paper’, students
summarized the state of knowledge about
a particular area, the perception of the
issue in the media and popular literature,
and the implications for policymakers.
Projected number of snow-covered days
(Image: Union of Concerned Scientists)
(Image: IPCC 2007)
Muir Glacier, Alaska, 1941 and 2004 (Images: William Field, Bruce Molnia, USGS)
FOR 797 Climate Change Effects on Natural Resources, Fall 2007
Final White Papers
Table of Contents
Chapter
Subject Area
Author
Page
Katherina Searing
3
1
Overview: the physical science basis
2
Paleoclimate and physical changes to the
atmosphere
Matt Distler
10
3
Changes to the oceans
Kacie Gehl
15
4
Changes to the cryosphere (snow, ice and frozen
ground)
Brandon Murphy
19
5
Global and regional climate models
Anna Lumsden
26
6
Impacts to freshwater resources
Nidhi Pasi
31
7
Carbon sinks and sequestration
Ken Hubbard
34
8
Impacts to coastal regions
Juliette Smith
38
9
Effects on biodiversity and species ranges
Lisa Giencke
43
10
Effects on species’ phenology
Laura Heath
47
11
Human health, crop yields and food production
Judy Crawford
52
12
Media perceptions of climate change: the Northeast
case study
Kristin Cleveland
57
13
Mitigation measures
Tony Eallonardo
62
Overview: the physical science
basis and expected impacts
Katherina Searing
EXECUTIVE SUMMARY
The fourth assessment report (AR4) of
the Intergovernmental Panel on Climate Change
(IPCC) is the most comprehensive report of
climate change science to date. This report states
that there is clear evidence that global
temperatures have increased 0.74°C and sea
levels have increased 17 cm in the 20th century.
By the end of the 21st century, global
temperatures are predicted to increase between
1.8 to 4.0°C and sea levels are expected to rise
between 18 and 59 cm. Most importantly, this
latest synthesis of climate change science reports,
with 90% confidence, that human activities have
caused a warming of the planet.
This new report also highlights some of the
likely impacts of increased temperatures and sea
level rise on six different sectors: freshwater
resources and their management; ecosystems,
their properties, goods and services; food, fiber
and forest products; coastal systems and low
lying areas; industry, settlement and society; and
human health. Additionally, some regions of the
world are identified as more vulnerable to the
effects of climate change, based on their
geographical location and adaptation capacity.
The media plays an important role in the
climate change arena by bringing the issue to
people’s attention and by helping to shape public
opinion. The release of the components of the
AR4 earlier in 2007 and the publication of final
version in November 2007, received a great deal
of media attention.
Some scientists have expressed concerns
about the findings of the IPCC due to the
exclusion of some recent scientific data
pertaining to the melting of glaciers and the ice
sheets. The IPCC has been criticized for not
communicating these limitations clearly in the
highly influential “Summary for Policymakers”
documents that are utilized by decision makers.
Aside from what is included in the AR4,
policymakers should consider the following
when constructing policies concerning climate
change: the spatial and temporal scale of climate
change and its impacts, the economics of the
prospective policies, and the security issues
regarding the effects of climate change.
INTRODUCTION
Climate change is an extremely
complex issue.
Due to this complexity,
policymakers required an objective and
comprehensive source of information regarding
this topic. The Intergovernmental Panel on
Climate Change (IPCC) was established by the
World Meteorological Organization (WMO) and
the United Nations Environmental Programme
(UNEP) in 1988. The stated goal of the IPCC is
to assess the scientific, technical and socioeconomic information pertaining to the
understanding of the risks associated with
anthropogenic climate change, its potential
impacts and the mitigation strategies available.
This international organization does not conduct
research nor does it collect climate related data.
They rely on peer reviewed scientific and
technical literature that has been published. The
IPCC also does not prescribe policy.
The IPCC published their fourth
assessment report (AR4) in 2007. Contributions
to this report were made by 1250 lead and
contributing authors from more than 130
countries and the report was reviewed by more
than 2500 scientific experts.1 This latest report
includes several advancements over the previous
reports (most recently the third assessment report
[TAR] in 2001)2, such as tighter estimates and a
better understanding of uncertainties provided by
substantial new data collection and research. 3
The IPCC is currently divided it to three working
groups. Working Group I (WG I) reports on
“The Physical Basis of Climate Change,”
Working Group II (WG II) focuses on “Climate
Change: Impacts, Adaptation and Vulnerability,”
and Working Group III deals with the
“Mitigation of Climate Change.” The findings
of WGs I and II will be discussed here.
1
Chairman Pauchuri, Chairman of the IPCC Presentation:
“IPCC Fourth Assessment Report: Synthesis Report”
Valencia, Spain. November 17, 2007.
2
IPCC, 2001: Summary for Policymakers. In: Climate
Change 2001: The Scientific Basis. Contribution of Working
Group I to the Third Assessment Report of the
Intergovernmental Panel on Climate Change [Houghton,
J.T.,Y. Ding, D.J. Griggs, M. Noguer, P.J. van der Linden, X.
Dai, K. Maskell, and C.A. Johnson (eds.)]. Cambridge
University Press, Cambridge, United Kingdom and New
York, NY, USA.
3
Chairman Pauchuri, Chairman of the IPCC Presentation:
“Introduction to AR4” Bonn, Germany. May 12, 2007.
SEARING OVERVIEW
FOR 797 CLIMATE CHANGE EFFECTS ON NATURAL RESOURCES FALL 2007
STATE OF THE SCIENCE
Working Group I: The Physical Science
Basis
Perhaps the most important statement in
the recent report of WG I is that “warming of the
climate system is unequivocal.” 4 , This
declaration is based on direct observations of
increased global air and ocean temperatures,
rising global sea level and reductions in snow
and ice in the Northern hemisphere. The 100year trend of increasing global average air
temperature was approximately 0.74°C, up from
0.60°C, given in the TAR. This report also
stated that the average ocean temperatures have
increase to depths up to 3000 m. This heating
leads to seawater expansion and consequently
sea level rise. Global average sea level rose on
average 1.8 mm per year from 1861 to 2003 and
there is some evidence that the rates of sea level
rise are increasing.5 Sea levels increased a total
of 17 cm during the 20th century. Reasons for the
increased sea level include the melting of the
glaciers, ice caps and polar ice sheets.
Warming trends have not been uniform
across the globe. Temperatures in the Arctic
have increased at almost twice the global average
rate over the past century and the sea ice extent
in the Arctic has shrunk by 2.7% per decade.
The last time the Polar Regions were warmer
than at present, for an extended period of time
(125,000 years ago), the melting of polar ice led
to 4 to 6 m of sea level rise. Information gained
from examining the paleoclimatic record informs
us that the warming that has occurred in the past
50 years is unusual in the past 1,300 years.
This observed warming is due to both
natural and anthropogenic forces. Only climate
models that incorporate both natural and
anthropogenic factors can explain the changes in
surface temperatures over the past 100 years.
Foremost among these anthropogenic factors is
the increased concentration of greenhouses gases,
especially CO2 and CH4. A number of models
have been constructed to predict how surface
temperatures would change with a continued
increase in greenhouse gases. These models
project increases of about 0.2°C are over the next
two decades for a range of greenhouse gas
emission scenarios. Projections for the year
2100 range from increases of 1.8 to 4.0°C,
depending upon the concentration of greenhouse
gases released into the atmosphere. Sea level is
projected to increase by 18 to 59 cm by the end
of the 21st century. 6 The upper sea level
projection has decreased since the TAR from 88
cm to 59 cm. Even if the greenhouse gas
concentrations could be stabilized, further
warming and sea level rise would continue for
centuries due to the effects of the greenhouse
gases already present in the atmosphere.
Working Group II: Impacts, Adaptation
and Vulnerability
The major findings of WG II in the AR47,
are that the impacts of climate change are
already occurring and they are now detectable at
a global scale. 8 Potential impacts of climate
change were identified in six sectors:
1)
2)
Freshwater resources and their management
„
Changes in average river runoff and
water availability
„
Drought affected areas will expand
„
Increased frequency
precipitation events
„
Increased flood risk
of
heavy
Ecosystems, their properties, goods and
services
„
Net carbon uptake will peak prior to
2050 and then weaken or reverse
6
4
IPCC, 2007: Summary for Policymakers. In: Climate
Change 2007: The Physical Science Basis. Contribution of
Working Group I to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change [Solomon, S., D.
Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt,
M.Tignor and H.L. Miller (eds.)]. Cambridge University
Press, Cambridge, United Kingdom and New York, NY,
USA.
5
The rate of sea level rise was higher between 1993 and 2003,
with the sea level increasing by 3.1 mm per year. However it
is not known whether this reflects a true increase or if it is
simply decadal variation. Ibid. pp 5-7.
The predicted sea level rise is for the years 2090-2099
relative to 1980-1999. Ibid. p 13.
7
IPCC, 2007: Summary for Policymakers. In: Climate
Change 2007: Impacts, Adaptation and Vulnerability.
Contribution of Working Group II to the Fourth Assessment
Report of the Intergovernmental Panel on Climate Change,
M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden
and C.E. Hanson, Eds., Cambridge University Press,
Cambridge, UK.
8
In the third assessment report (2001), only impacts at the
regional scale could be detected. Presentation of WGII 2007:
“Climate Change 2007: Impacts, Adaptation and
Vulnerability” Brussels. April 6, 2007.
2
SEARING OVERVIEW
3)
„
Around 20 – 30% of animal and plant
species are likely to be at an increased
risk of extinction
„
Major changes in ecosystem structure
and function
„
Coral reefs and marine shelled
organisms are particularly vulnerable
Food, fiber and forest products
„
5)
6)
Crop productivity will increase
slightly at mid- to high latitudes for
temperature increases of 1-3°C
increases and will decrease beyond
that
„
Crop productivity at low latitudes will
decline for even small temperature
increases (1-2°C)
„
Commercial timber productivity may
increase slightly with increased
temperatures, with large regional
variability
„
4)
FOR 797 CLIMATE CHANGE EFFECTS ON NATURAL RESOURCES FALL 2007
Changes in the distribution and
production of fish species are
expected with negative effects on
aquaculture and fisheries
Coastal systems and low lying areas
„
Increased coastal erosion due to
higher sea levels
„
More frequent coral bleaching events
„
Negative effects on coastal wetlands
(salt marshes and mangroves) due to
sea level rise
„
Low lying areas are
vulnerable to flooding
extremely
Industry, settlement and society
„
Those in coastal and river flood plains
are the most vulnerable
„
Poor communities are also extremely
vulnerable (limited adaptive capacity)
Human health
„
Increases
in
malnutrition
diarrhoreal diseases
and
„
Increases in death and injury from
heat waves, floods, storms, fires, and
droughts
„
Changes in the distribution
infectious disease vectors.
of
Given these potential impacts, it is possible
to identify regions of world that are the most
vulnerable. The regions in the world that are
most at risk are the Arctic, Africa (particularly
Sub-Saharan Africa), small islands and the Asian
mega-deltas. Some adaptation to the effects of
climate change is occurring now but more will
be required in order to contend with the future
impacts of climate change. These responses may
include a variety of adaptation mechanisms, such
as technological, behavioral, managerial and
policy changes.
PERSPECTIVES IN THE MEDIA AND PUBLIC
POLICY
The media has a very important role in
the climate change arena. The media affects the
public by bringing the issue to the attention of
the public and by influencing public opinion on
climate change through issue framing.
Many articles were written in response to
the release of the report by WG I in early
February 2007. 9 These articles focused on the
IPCC’s conclusions that climate change is
“unequivocal” and that it is “very likely” caused
by human activities.10 After the report of WG II
was released in April 2007, many articles
appeared in national newspapers as well. 11
These reports focused on the potential impacts of
the proposed temperature increases, such as
droughts, flooding, rising sea level and food
shortages. Extremely vulnerable regions, both
globally (mentioned in the previous section) and
nationally, such as the Southwestern U.S., were
discussed in several reports.
Criticisms of the IPCC
Several climate experts have expressed
concerns about the lessened worst-case scenario
for sea level rise in the new IPCC report (down
from 88 cm in the TAR to 59 cm in the AR4).12
The panel did not consider or include new
evidence on the rate of melting of glaciers and
the Greenland and West Antarctic ice sheets
because there was a set deadline of December
9
See Appendix I for a list of selected newspaper articles
published around the release of the report from WG I.
10
greater than 90% certainty
11
See Appendix II for a list of selected newspaper articles
published around the release of the report from WG II.
12
Cornelia Dean, Andrew C. Revkin contributed
reporting.. Even Before Its Release, World Climate Report Is
Criticized as Too Optimistic. New York Times (Late
Edition (east Coast)) [serial online]. February 2, 2007:A.11.
3
SEARING OVERVIEW
FOR 797 CLIMATE CHANGE EFFECTS ON NATURAL RESOURCES FALL 2007
2005 for the submission of scientific information.
However, limitations such as this are often not
discussed in the highly consulted and cited
“Summary for Policymakers” of the Working
Groups. This demonstrates the difficulty of
making scientific statements and predictions in a
rapidly progressing field and reporting them in a
condensed summary report. This highlights one
of the difficulties of an international panel
involving many participants and a rigorous and
lengthy review process. To remedy this problem,
it has been suggested that smaller groups be
formed to focus on particular aspects of climate
change and create special reports on a more
frequent basis.13
demonstrating the need for a comprehensive
global plan.14
Climate change is now being considered
a security threat. A military panel of retired
generals and admirals released a report in April
that said, “projected climate change poses a
serious threat to America’s national security.”15
This report describes climate change as a “threat
multiplier,” that may exacerbate instability
throughout the world. The United Nations
Security Council also held a debate about the
impacts of climate change on peace and security
in April 2007.
CONSIDERATIONS FOR POLICYMAKERS
APPENDIX I
Considerations for Policymakers are
vast and complex. Aside from the information
included within the AR4, policymakers should
consider the following aspects of climate change.
Newspaper articles published around the
release of WG I in February 2007.
Security
1)
Beth Daley Climate report faults humans
for warming; Panel voices more certainty
than
in
2001 :[3
Edition]. Boston
Globe
[serial
online]. February 2, 2007:A.3.
2)
Beth Daley UN study spurs call to fight
warming;
Panel
says
rise
is
`unequivocal' :[3
Edition]. Boston
Globe
[serial
online]. February 3, 2007:A.1.
3)
ERIC BERGER Severe heat, drought
predicted for life in 22nd-century Texas /
Global warming report also warns of more
flooding :[3 STAR , 0 Edition]. Houston
Chronicle
[serial
online]. February 3, 2007:A.1.
4)
Gautam Naik and Jeffrey Ball U.N. Report
Adds
Pressure
to
Global-Warming
Fight. Wall Street Journal (Eastern
Edition)
[serial
online]. February 2, 2007:A.4.
5)
Ian Sample, Science correspondent
National: IPCC report: Why the news about
warming is worse than we thought:
feedback: Oceans, soil and trees will
become worse at absorbing carbon dioxide
Spatial and Temporal Scale
Climate change is a global phenomenon
that should be addressed in a global context with
international cooperation. Although the regional
impacts of climate change vary, an international
effort must be made to supply information and
technical expertise to developing nations to assist
them with reducing their emissions or adapting
to the impacts of climate change.
Particular attention should be given to the
fact that warming will occur over the next
century due to the greenhouse gases already in
the atmosphere.
Therefore, adaptation and
mitigation strategies are necessary to cope with
inevitable warming and sea level rise. Measures
to reduce greenhouse gas emissions are also
necessary to reduce future impacts of climate
change.
Economics
Efforts to reduce greenhouse emissions
are often viewed to be perilous to the economy.
While the Bush administration accepts the recent
findings of the IPCC, they oppose mandatory
reductions in greenhouse gas emissions because
of the potential damage to the U.S. economy.
The administration warns of industries moving
abroad, possibly to developing countries, to
avoid stringent reductions in the U.S., again
13
Oppenheimer, M., O’Neill, B.C., Webster, M., and
Agrawala, S. 2007. The Limits of Consensus. Science. 317:
p1505-1506.
14
Zachary Coile Report spurs calls for aggressive action /
White House accepts findings but rejects mandatory
cuts :[FINAL Edition]. San Francisco Chronicle [serial
online]. February 3, 2007:A.6.
15
The Center Naval Analyses Corporation. 2007. National
Security and the Threat of Climate Change, available at
http://SecurityAndClimate.cna.org/
4
SEARING OVERVIEW
FOR 797 CLIMATE CHANGE EFFECTS ON NATURAL RESOURCES FALL 2007
as temperatures rise: Evidence for warming:
what
the
scientists
found. The
Guardian
[serial
online]. February 3, 2007:12.
6)
James Bronzan Ever-Firmer Statements on
Global Warming. New York Times (Late
Edition
(east
Coast))
[serial
online]. February 4, 2007:2.
7)
Jane Kay A WARMING WORLD /
Climate Change Report / Grim global
warming prognosis for Western U.S. /
International group says quick action can
mitigate
some
effects :[FINAL
Edition]. San Francisco Chronicle [serial
online]. February 3, 2007:A.1.
8)
9)
John J. Fialka Politics & Economics:
Global-Warming Report Gets U.S.
Emphasis. Wall Street Journal (Eastern
Edition)
[serial
online]. February 3, 2007:A.4.
Katy Human Denver Post Staff Writer .N.
climate-change panel's projections for '01
borne out The earlier estimates were called
alarmist at the time, but updated data
indicate they were conservative :[Final
Edition]. Denver
Post
[serial
online]. February 2, 2007:A.4.
10) MIKE TONER 'We're creating a different
planet': Scientists warn climate changes
might worsen :[Main Edition]. The Atlanta
Journal
Constitution
[serial
online]. February 3, 2007:A.5.
11) Patrick O'Driscoll Report says warming
'very likely' caused by people, will last
centuries :[FINAL
Edition]. USA
TODAY
[serial
online]. February 2, 2007:A.6.
12) Peter N. Spotts Staff writer of The
Christian Science Monitor A clearer global
climate forecast ; A report coming Friday
will offer the strongest consensus yet on
how the Earth will change :[ALL
Edition]. The
Christian
Science
Monitor
[serial
online]. February 1, 2007:01.
13) Peter N. Spotts Staff writer of The
Christian Science Monitor In wake of latest
climate report, calls mount for global
response ; UN findings name human
activity as 'very likely' cause of
'unequivocal'
climate
change :[ALL
Edition]. The
Christian
Science
Monitor
online]. February 5, 2007:02.
[serial
14) Peter N. Spotts Staff writer of The
Christian Science Monitor Reports on
global warming lag behind the science ;
The newest UN-sponsored assessment left
out research that suggests more dire climate
change :[ALL Edition]. The Christian
Science
Monitor
[serial
online]. February 7, 2007:03.
15) SETH BORENSTEIN Report: Global
warming to last for centuries / Scientists
say it's `very likely' caused by people :[3
STAR
,
0
Edition]. Houston
Chronicle
[serial
online]. February 2, 2007:1.
16) Seth Borenstein, Associated Press Report
steps up warning on global warming threat ;
In strongest wording yet, humans get
blame :[Chicago Final Edition]. Chicago
Tribune [serial
online]. February 2, 2007:9.
17) Thomas H. Maugh II and Karen Kaplan
Deal with warming, don't debate it,
scientists warn; The U.N.'s stark report puts
policymakers on notice, though there is no
consensus
on
action :[HOME
EDITION]. Los Angeles Times [serial
online]. February 3, 2007:A.1.
18) Zachary Coile Report spurs calls for
aggressive action / White House accepts
findings
but
rejects
mandatory
cuts :[FINAL Edition]. San Francisco
Chronicle
[serial
online]. February 3, 2007:A.6.
19) Cornelia
Dean, Andrew
C.
Revkin
contributed reporting.. Even Before Its
Release, World Climate Report Is
Criticized as Too Optimistic. New York
Times (Late Edition (east Coast)) [serial
online]. February 2, 2007:A.11.
20) ELISABETH
ROSENTHAL
and
ANDREW
C.
REVKIN, Elisabeth
Rosenthal reported from Paris, and Andrew
C. Revkin from New York. Felicity
Barringer contributed reporting from
Washington.. Science Panel Says Global
Warming Is 'Unequivocal'. New York
Times (Late Edition (east Coast)) [serial
online]. February 3, 2007:A.1.
21) Global Warning; The world's scientists
agree, again, that climate change is a big
5
SEARING OVERVIEW
FOR 797 CLIMATE CHANGE EFFECTS ON NATURAL RESOURCES FALL 2007
problem :[FINAL
Edition]. The
Washington
Post
[serial
online]. February 5, 2007:A.14.
22) John
Leicester, the
Associated
Press. Climate change report's forecast is
bleak :[First Edition]. St. Louis Post
Dispatch
[serial
online]. February 4, 2007:A.5.
23) Key players react to the IPCC global
warming
report :[ALL
Edition]. The
Christian Science Monitor
[serial
online]. February 8, 2007:25.
24) Melting doubts / The latest United Nations
assessment of the human role in global
warming should spur a U.S. search for
solutions :[3 STAR , 0 Edition]. Houston
Chronicle
[serial
online]. February 3, 2007:B.6.
25) Political climate shifts as verdict on
warming arrives :[FINAL Edition]. USA
TODAY
[serial
online]. February 2, 2007:A.8.
26) Seth Borenstein, THE ASSOCIATED
PRESS. Global warming is here to stay
That's the message in a climate report by
the
world's
leading
experts :[Third
Edition]. St. Louis Post - Dispatch [serial
online]. February 3, 2007:A.22.
27) Seth
Borenstein, the
associated
press. Finger pointed at us all Climate panel
agrees on most powerful warning yet,
saying human activities are "very likely"
causing rising seas and stronger
hurricanes :[Third Edition]. St. Louis Post
Dispatch
[serial
online]. February 2, 2007:A.1.
APPENDIX II
Newspaper articles published around the
release of WG II in April 2007.
1)
ANDREW C. REVKIN and TIMOTHY
WILLIAMS Global Warming Called
Security Threat. New York Times (Late
Edition (east Coast)) [serial online]. April
15, 2007:1.25.
2)
Andrew C. Revkin Wealth and Poverty,
Drought and Flood: Reports From 4 Fronts
In the War on Warming. New York Times
(Late Edition (east Coast)) [serial online].
April 3, 2007:F.4.
3)
Beth Daley A CLIMATE CHANGE
WARNING; Panel says humans are
probably causing shifts around world :[3
Edition]. Boston Globe [serial online].
April 7, 2007:A.1.
4)
Beth Daley US lags on plans for climate
change :[3 Edition]. Boston Globe [serial
online]. April 5, 2007:A.1.
5)
Brad Knickerbocker White House expected
to feel the heat from Supreme Court's
ruling on global warming :[ALL Edition].
The Christian Science Monitor [serial
online]. April 5, 2007:10.
6)
Dan Vergano Study forecasts new 'Dust
Bowl' :[FINAL Edition]. USA TODAY
[serial online]. April 6, 2007:A.8.
7)
David Adam, Environment correspondent
Climate change will hit poorest hardest, say
UN scientists. The Guardian [serial
online]. April 6, 2007:6.
8)
David Adam, Environment correspondent
Environment: UN: we have the money and
know-how to stop global warming: Report
obtained by the Guardian spells out strategy
to reverse climate change. The Guardian
[serial online]. April 28, 2007:6.
9)
Ed Pilkington, New York UK to raise
climate talks as security council issue. The
Guardian [serial online]. April 16, 2007:24.
10) Jane Kay Report predicts climate calamity /
All continents face drought, starvation,
rising seas, panel says :[FINAL Edition].
San Francisco Chronicle [serial online].
April 7, 2007:A.1.
11) Joseph Schuman The Morning Brief: A
Climate Report Brings Dire Warnings, and
Frustration :Online edition. Wall Street
Journal (Eastern Edition) [serial online].
April 6, 2007:
12) Juliet Eilperin - Washington Post Staff
Writer Climate Panel Confident Warming
Is Underway; Report to Detail the Role of
humans
:[FINAL
Edition].
The
Washington Post [serial online]. April 5,
2007:A.1.
13) Juliet Eilperin - Washington Post Staff
Writer Military Sharpens Focus on Climate
Change; A Decline in Resources Is
Projected to Cause Increasing Instability
Overseas
:[FINAL
Edition].
The
6
SEARING OVERVIEW
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Washington Post [serial online]. April 15,
2007:A.6.
14) Juliet Eilperin - Washington Post Staff
Writer Warming Predicted to Take Severe
Toll on U.S :[FINAL Edition]. The
Washington Post [serial online]. April 17,
2007:A.12.
15) Katy Human Denver Post Staff Writer
Flame-plagued summers part of climate
forecast The next chapter of a report on
global warming predicts a dried-out West
battling more and more fires at a cost of
billions :[Final Edition]. Denver Post
[serial online]. April 3, 2007:B.4.
16) Maggie Farley The World; U.N. discusses
climate change; Some Security Council
members say the issue isn't germane; others
argue that it threatens peace and
security :[HOME EDITION]. Los Angeles
Times [serial online]. April 18, 2007:A.8.
17) Marc Kaufman - Washington Post Staff
Writer Southwest May Get Even Hotter,
Drier; Report on Warming Warns of
Droughts
:[FINAL
Edition].
The
Washington Post [serial online]. April 6,
2007:A.3.
18) Mark Magnier THE WORLD; U.N. report
raises pressure on China to cut pollution;
Economic
growth
has
brought
environmental disaster, but fixing it is
complicated by politics, poverty and
tradition :[HOME EDITION]. Los Angeles
Times [serial online]. April 8, 2007:A.3.
19) Mark Martin Legislature flooded with bills
about climate crisis / Poll-driven politicians
see need to tackle global warming :[FINAL
Edition]. San Francisco Chronicle [serial
online]. April 2, 2007:A.1.
create another Dust Bowl. Water politics
could also get heated :[HOME EDITION].
Los Angeles Times [serial online]. April 6,
2007:A.1.
23) Alan Zarembo, Thomas H. Maugh II. Dire
warming report too soft, scientists say;
Some nations lobbied for changes that blunt
the study, contributors charge. The U.N.
forecast is still bleak :[HOME EDITION].
Los Angeles Times [serial online]. April 7,
2007:A.1.
24) JAMES KANTER and ANDREW C.
REVKIN,
James
Kanter
reported
fromBrussels, and Andrew C. Revkin from
New York.. Scientists Detail Climate
Changes, Poles to Tropics. New York
Times (Late Edition (east Coast) [serial
online]. April 7, 2007:A.1.
25) Many species feel impact of global
warming, panel finds :[Fourth Edition]. St.
Louis
Post-Dispatch [serial
online]. April 1, 2007:A.6.
26) Andrew C. Revkin. "U.N. Draft Cites
Humans in Current Effects of Climate
Shift. " New York Times [New York,
N.Y.] 5 Apr. 2007, Late Edition (East
Coast): A.6.
27) Karen Kaplan, Thomas H. Maugh II. "The
Nation; Military panel calls global warming
a security threat; Food shortages, melting
ice and natural disasters pose danger, report
says :[HOME EDITION]. " Los Angeles
Times
[Los
Angeles,
Calif.] 17 Apr. 2007,A.16.
20) Peter N Spotts Surviving a warmer world:
Global forecast is 'mostly dry' :[ALL
Edition]. The Christian Science Monitor
[serial online]. April 5, 2007:1.
21) A Consensus on Crisis; A U.N. panel
details the distress that global climate
change
might
cause
human
societies
:[FINAL
Edition].
The
Washington Post [serial online]. April 8,
2007:B.6.
22) Alan Zarembo, Bettina Boxall. The Nation;
A permanent drought seen for Southwest;
A study says global warming threatens to
7
Paleoclimate overview report
Matt Distler
EXECUTIVE SUMMARY
Earth’s climate over the last 1 million years
has changed on a 100,000 year (100 ka) cycle,
driven by parameters related to earth’s orbit. Ice
core data now covers the last 8 cycles, revealing
a repeated pattern of gradual cooling into 100 ka
glacial periods followed by rapid warming to 8
ka to 28 ka interglacial conditions like those experienced today. New ice core evidence shows
the interglacial of 410 ka, like our current interglacial, was particularly long (~28 ka), suggesting that orbital parameters do not necessarily
predict an imminent return to glacial conditions.
Paleoclimate research in the last several
decades has better characterized rapid climate
change events superimposed upon the long-term
orbital-driven cycle. Ice core data from
Greenland reveals that these events, including
the Little Ice Age (LIA) in the last 200 years, are
characterized by significant changes in temperature and climate over continental or global scale
and may initiate within decades. These events
are often triggered by changes in ocean circulation, including changes to the strength of the
Atlantic thermohaline circulation system. In addition, Greenland ice core data show that the
circulation patterns characteristic of the LIA
have not ended, despite increased global temperatures, implying possible anthropogenic, not
orbital, causes of warming.
INTRODUCTION
The degree and timing of Earth’s tilt on
it’s axis as it circles the sun and the shape of its
orbit are the major drivers of earth’s climate on a
multi-millenial timescale. The eccentricity
(variation from circular) of earths orbit around
the sun produces a 100,000 year (100 ka) cycle
of greater and lesser insolation, the obliquity (tilt)
of the orbit drives a 41 ka cycle, and the precession (timing of seasons relative to orbital distance from sun ) driving a 22 ka cycle of varying
seasonality. Together these parameters produce
an approximately 100 ka cycle of glacial and
interglacial periods that have characterized the
earth’s climate for much of the last million years.
The changing position of continents, which dramatically affect ocean and heat circulation
around the globe may have played a crucial part
in modulating the effects of these orbital cycles
on the climate over time periods longer than 1
million years.
Other factors affect the earth’s climate
on smaller temporal scales, however, including
changes in ocean circulation, atmospheric greenhouse gas concentrations, terrestrial albedo conditions, vulcanism, asteroid impacts, and many
others. There is accumulating evidence that the
climate is currently warming, and that increases
in anthropogenically produced greenhouse gases,
especially carbon dioxide (CO2), may be a primary driver of this change (Mayewski and White,
2002).
Paleoclimatic reconstructions provide important clues as to the past interactions between
these factors, orbital parameters, and past climate
change, allowing us to better predict the trajectory of the modern climate. Ice cores in particular are important data sources for paleoclimatic
reconstructions, due to their high temporal resolution and the direct inclusion of atmospheric
components, including CO2, in the ice. Other
characteristics of ice and included impurities,
such as dust or ice density, serve as climate proxies, telling us more about weather conditions in
the past. This report endeavors to give an overview of the recent advances in our knowledge of
paleoclimates based on ice core data, and discusses the implications of this research for future
climate change.
STATE OF THE SCIENCE
Recent ice cores in the Antarctic have extended the length of our high resolution ice core
records to approximately 800 ka (EPICA, 2004),
improving our understanding of the very longterm changes in the orbital climate cycles of
earth. The new records corroborate the general
pattern of temperature and greenhouse gas concentration changes seen in previous records of
recent glaciations; glacial periods are characterized by slowly decreasing temperatures and CO2
concentrations culminating in a period of cold
but variable climate lasting approximately 100
ka. Glacial periods then transition more abruptly
to a warmer interglacial similar to our current
Holocene period.
The recent long Antarctic cores extend
back to four glacial cycles not yet observed in ice
cores, and show that the oldest of these glacial
periods seem increasingly driven by the two
shorter (41ka, 22ka) orbital cycles, and that interglacials were cooler during this period. This
change in the orbital cycles toward beginning of
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the last 1 million years is in keeping with sediment core results, but is not yet completely understood. Another new finding is the extended
length of the interglacial period that occurred
410 ka ago, the first cycle beyond the reach of
earlier ice cores. The three more recent interglacials we’ve studied up until these new data have
all been approximately 8 ka in length, which
suggested that the current 10 ka length of our
own Holocene might require a non-orbital-driven
explanation, such as early agricultural
CO2/methane emissions. The recently revealed
410 ka interglacial, however, was approximately
28 ka in duration (before agriculture and without
an accompanying rise in CO2), showing that orbital parameters may be able to explain our long
Holocene (EPICA, 2004; White, 2004).
High resolution ice cores from Greenland
(GISP2 project) are informative about recent
climatic changes, particularly the speed with
which major climate change can occur. Johnsen
and others (1992) compare the results of four
Greenland ice cores, and show conclusively that
short (0.5 to 2 ka) periods of warm interstadial
conditions occurred irregularly and repeatedly
during the latter part of the last glaciation. From
the raised δ18O values (signifying increased temperatures) these interstadials appear to be characterized by temperatures ~7ºC warmer than the
cold glacial conditions, only 5-6 ºC cooler than
modern Greenland temperatures. Perhaps more
importantly, annual resolution records confirm
earlier speculation that these warm periods initiate abruptly, within a few decades. Subsequent
cooling to glacial conditions was a more gradual
process. These RCCEs and later ones during the
recent interglacial have been linked to changes in
Atlantic Ocean circulation, which may be slowed
or stopped by increased freshwater input from
melting glaciers during periods of warming
(Mayewski and White 2002). The speed of these
changes suggests that the climate systems is
more dynamic and variable at a shorter temporal
scale than previously thought.
Greenland ice cores, coupled with longterm observational data on weather across the
North Atlantic, have also shed light on relatively
recent (historical) climate change, helping to sort
out the influences of human civilization on the
climate versus the suite of orbital, solar, and
other “natural” influences on climate. Dawson
and others (2003) compared temperature records
from Greenland and Northern Europe dating
back to the 1880s, confirming earlier observations that cold Greenland winters are associated
with warmer northern European winters. This
effect is due to a “seesaw” of high pressure systems affecting the paths of cold air across the
north Atlantic. Ice core data from Dawson’s
team in Greenland match historical temperature
records well and show that colder years in
Greenland are also associated with greater sodium (Na+) deposition from sea salts, a marker of
increased storminess. Furthermore, the period
from 1400 A.D. to 1900 A.D., a widespread cold
period known as the Little Ice Age (LIA) is characterized by more frequent storms in Greenland
(despite the inverse year-by-year correlation between temperatures in Greenland and Europe).
This study shows that the degree of storminess in
Greenland is a good indicator of RCCE cooling
in Europe and possibly other parts of the world.
Interestingly, the return to a warmer post-LIA
climate ~1900 A.D. is not accompanied by a
resumption of the storm circulation patterns from
the previous warm period. Rather, LIA patterns
in the ice core continue to the present (Dawson et
al. 2003; Mayewski and White, 2002.), despite
the global warming of approximately 1 degree C
since the turn of the 19th century. These data
provide some evidence that the LIA atmospheric
conditions continue, but that anthropogenic effects on climate have cancelled out the LIA cooling (Mayewski and White 2002).
PERSPECTIVES IN THE MEDIA AND PUBLIC
POLICY
Compared to news of current changes in
weather, temperature, organisms’ reaction to
weather, or even output from predictive climate
models, paleoecological research is less often
presented in the popular press. This may be due
to the indirect connection between paleoecological findings and our predictive capabilities for
future climate as well as the highly technical
nature of paleoclimatic techniques and results.
Nonetheless, there are a number of sources that
have brought paleoecological data to the public
eye. Examples include The Weathermakers
(Flannery, 2005), portions of Al Gore’s (2006)
An Inconvenient Truth, the IPCC summary for
policymakers, and a few popular books specifically about paleoclimate.
Flannery’s book uses paleoecological
sources to place current climate in perspective
and highlights some paleo-events as analogs for
future change, including the massive release of
methane at the Paleocene-Eocene boundary, 55
million years ago. An Inconvenient Truth provides greenhouse gas data from ice cores, but,
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like many popular sources, simplifies the results
to make a more forceful point. Gore shows that
modern CO2 levels are well above past Pleistocene levels, but fails to explain complex feedbacks between CO2 levels and global temperature, leading to confusion about cause and effect.
The IPCC summary for policymakers (2007)
focuses on paleoecological estimates of sea level
rise in past interglacials, past variability in CO2
and other greenhouse gas levels from ice cores,
and past estimates of temperature. A few popular
books are directed entirely toward paleoecological findings, including The Ice Chronicles
(Mayewski and Frank, 2002) and The two-mile
time machine (Alley, 2000), allowing more comprehensive discussion and summary of this complex field.
CONSIDERATIONS FOR POLICYMAKERS
The science outlined above is part of a
growing body of paleoecological literature that
aims to better describe the history of earth’s past
climate changes in order to better understand
future change. Some of the most important lessons from these studies are these:
1)
Earth’s climate is continuously variable,
undergoing change at all temporal scales
(gradual and rapid, short and long-term).
Our civilization needs to strengthen its ability to adapt to oncoming climate change.
2)
Major climate change, particularly warming,
may happen very quickly, within a century
or even decades. Certain periods (for instance, the last glacial period) may be more
prone to these major, rapid changes, but
there is evidence that they re-occur approximately every 1400 years (Mayewski
and White, 2002). This instability of our
climate system on short timescales should
cause us to work on improving our adaptability to such changes, but also caution us
to avoid any anthropogenic impacts that
might set off feedbacks that bring on
RCCEs (such as causing significant melting
of polar/arctic freshwater into the North Atlantic).
3)
Human impact on climate may already be
observable in paleoecological records. Although new Antarctic cores suggest our
current interglacial may be long due to orbital forcing, not anthropogenic influences
beginning ~10 ka, Greenland cores suggest
our impact since ~1900 A.D. may have al-
ready offset Little Ice Age conditions. This
research adds to the vast and growing body
of evidence for anthropogenic effects on
the climate, all of which represents a serious argument for reducing greenhouse gas
emissions, improving our ability as a civilization to adapt to changing climate and
pursuing possible technologies to remediate
greenhouse gas effects.
REFERENCES
Alley, R.B. 2000. The Two-mile Time Machine:
Ice Cores, Abrupt Climate Change, and Our
Future. Princeton University Press.
An inconvenient Truth. 2006. (Film) Dir. D.
Guggenheim. Perf. A. Gore. Lawrence
Bender Productions.
Dawson, A.G. L.Elliott, P. Mayewski, P. Lockett,
S. Noone, K. Hickey, T. Holt, P. Wadhams,
and I. Foster. 2003. Late-Holocene North
Atlantic climate ‘seesaws’, storminess
changes and Greenland ice sheet (GISP2)
palaeoclimates. The Holocene, 4 (13): 381 392.
Abstract: The oxygen-isotope record of palaeotemperature from Greenland ice cores
has for many years been the kingpin of climate reconstructions for the North Atlantic
region and northern Europe, An air temperature, 'seesaw' between Greenland and northern Europe. first described in AD 1765, is
also well known and is related to the North
Atlantic Oscillation (NAO). Whereas the
NAO index series is based on instrumental
records of air pressure, the North Atlantic
climate 'seesaw' has conventionally been
based on air-temperature records, Here we
describe relationships between this 'seesaw'
mechanism and the Greenland (GISP2) oxygen-isotope chronology of air-temperature
variations, as well as relationships between
GISP2 Na+ (sea-salt) variations and instrumental records of North Atlantic storminess.
The GISP2 proxy air-temperature record is
calibrated for the last 130 years with instrumental weather records for West Greenland,
while the Na+ series is compared with instrumental records of North Atlantic storminess change. Reconstruction of an annual series of these climate parameters for the last
1000 years shows that during the 'Mediaeval
Warm Period' there were no years characterized by high Na+ extremes (high North At-
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lantic storminess) but there were many years
when there were extremes of temperature.
Remarkably, there A ere no years of exceptionally low air temperature and high Na+
precipitation at GISP2 between AD 1650
and 1710. a period of time that in northern
Europe incorporates the period of maximum
'Little Ice Age' cooling. It would appear also
that for the last thousand years the most extreme 'seesaw' winters when GISP2 temperatures were very low and Na+ concentrations were high occurred in discrete clusters
and pairs of years.
EPICA community members*. 2004. Eight glacial cycles from an Antarctic ice core. Nature 429: 623-628.
Abstract: The Antarctic Vostok ice core
provided compelling evidence of the nature
of climate, and of climate feedbacks, over
the past 420,000 years. Marine records suggest that the amplitude of climate variability
was smaller before that time, but such records are often poorly resolved. Moreover, it
is not possible to infer the abundance of
greenhouse gases in the atmosphere from
marine records. Here we report the recovery
of a deep ice core from Dome C, Antarctica,
that provides a climate record for the past
740,000 years. For the four most recent glacial cycles, the data agree well with the record from Vostok. The earlier period, between 740,000 and 430,000 years ago, was
characterized by less pronounced warmth in
interglacial periods in Antarctica, but a
higher proportion of each cycle was spent in
the warm mode. The transition from glacial
to interglacial conditions about 430,000
years ago (Termination V) resembles the
transition into the present interglacial period
in terms of the magnitude of change in temperatures and greenhouse gases, but there
are significant differences in the patterns of
change. The interglacial stage following
Termination V was exceptionally long 28,000 years compared to, for example, the
12,000 years recorded so far in the present
interglacial period. Given the similarities between this earlier warm period and today,
our results may imply that without human
intervention, a climate similar to the present
one would extend well into the future.
IPCC, 2007: Summary for Policymakers. In: Climate
Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment
Report of the Intergovernmental Panel on Climate
Change [Solomon, S., D. Qin, M. Manning, Z. Chen,
M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller
(eds.)]. Cambridge University Press, Cambridge,
United Kingdom and New York, NY, US.
Flannery, Tim. 2005. The Weathermakers. Atlantic Monthly Press, New York.
Johnsen, S.J., H.B. Clausen, W. Dansgaard, K.
Fuhrer, N. Gunderstrup, C.U. Hammer, P.
Iversen, J. Jouzel, B. Stauffer, and J.P,
Steffensen. 1992. Irregular glacial interstadials recorded in a new Greenland ice core.
Nature 359: 311-313.
Abstract: The Greenland ice sheet offers the
most favourable conditions in the Northern
Hemisphere for obtaining high-resolution
continuous time series of climate-related parameters. Profiles of 18O/16O ratio along
three previous deep Greenland ice cores1–3
seemed to reveal irregular but well-defined
episodes of relatively mild climate conditions (interstadials) during the mid and late
parts of the last glaciation, but there has
been some doubt as to whether the shifts in
oxygen isotope ratio were genuine representations of changes in climate, rather than artefacts due to disturbed stratification. Here
we present results from a new deep ice core
drilled at the summit of the Greenland ice
sheet, where the depositional environ-ment
and the flow pattern of the ice are close to
ideal for core recovery and analysis. The results reproduce the previous findings to such
a degree that the existence of the interstadial
episodes can no longer be in doubt. According to a preliminary timescale based on
stratigraphic studies, the interstadials lasted
from 500 to 2,000 years, and their irregular
occurrence suggests complexity in the behaviour of the North Atlantic ocean circulation.
Mayewski, P. and F. White. 2002. The Ice
chronicles. University Press of New England.
White, J.W.C. 2004. Do I hear a million? Science 304: 1609-1610.
*Laurent Augustin1, Carlo Barbante2, Piers R. F.
Barnes3, Jean Marc Barnola1, Matthias Bigler4,
Emiliano Castellano5, Olivier Cattani6, Jerome
Chappellaz1, Dorthe Dahl-Jensen7, Barbara Delmonte1,8, Gabrielle Dreyfus6, Gael Durand1,
Sonia Falourd6, Hubertus Fischer9, Jacqueline
Flu¨ ckiger4, Margareta E. Hansson10, Philippe
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Huybrechts9, Ge´ rard Jugie11, Sigfus J. Johnsen7,
Jean Jouzel6, Patrik Kaufmann4, Josef Kipfstuhl9,
Fabrice Lambert4, Vladimir Y. Lipenkov12,
Genevie` ve C. Littot3, Antonio Longinelli13,
Reginald Lorrain14, Valter Maggi8, Valerie Masson-Delmotte6, Heinz Miller9, Robert Mulvaney3,
Johannes Oerlemans15, Hans Oerter9, Giuseppe
Orombelli8, Frederic Parrenin1,6, David A. Peel3,
Jean-Robert Petit1, Dominique Raynaud1, Catherine Ritz1, Urs Ruth9, Jakob Schwander4, Urs
Siegenthaler4, Roland Souchez14, Bernhard
Stauffer4, Jorgen Peder Steffensen7,
5
Ocean Acidification
Effects of Anthropogenic CO2 on Marine
Calcifying Organisms, Ocean Water Chemistry and What the Future has in Store…
Kacie Gehl
EXECUTIVE SUMMARY:
Anthropogenic release of carbon dioxide into the atmosphere is affecting the oceans
profoundly. The oceans are the main source of
carbon sequestration on the planet and without
this storage; the planet may be currently uninhabitable. As the oceans take up carbon dioxide,
it combines with calcium ions to produce carbonic acid (Orr, et. al., 2005). This, in effect,
decreases the alkalinity of the oceans. With rising levels of undersaturation, there is a move to
more acidic ocean waters (Orr, et. al., 2005),
(Feely, et. al., 2004). The slight change creates
an environment that is devastating for marine
calcifying organisms. Because there is a depleted amount of calcium in the ocean water,
calcifying organisms such as pteropods and corals are no longer able to maintain or produce
shells or skeletons (Orr, et. al., 2005), (Hughes,
et. al., 2003). This disrupts the basis of the food
chain in many ecosystems. As the oceans can
only sequester a specific amount of carbon dioxide of which the value is unknown, it is of the
utmost importance to understand as completely
as possible, the effects of acidification of the
oceans on calcifying organisms and the thresholds that exist concerning where and when the
most abrupt changes in calcium saturation will
occur.
INTRODUCTION:
Changes in ocean water chemistry occur
from the deposition of atmospheric carbon dioxide into the oceans. This process enables life on
land to exist more comfortably as we would have
a much warmer and less pleasant climate without
this sequestration. When the critical threshold is
reached, in which the oceans will be a net source
of carbon, the climate will warm at a greater extent. However, already, effects in the oceans are
evident. Marine calcifying organisms, which
form the basis of many food chains, are struggling to survive. As CO2 depletes the free calcium ions in the water and becomes carbonic
acid, calcifying organisms are no longer able to
build new shells or maintain the ones they currently have, because their source of calcium is
depleted (Orr, et. al., 2005). Research is currently needed in many areas to gain a better understanding of how much time we have to possibly mitigate current damage and prevent future
damage to oceans and calcifying organisms.
Although there is much we do not know
concerning the process, we do know that the net
source of carbon to the oceans is of an anthropogenic nature. As the IPCC defines, even at a
zero emissions standstill in CO2 pollution, the
oceans will continue to take up carbon dioxide
because this system is lagging behind. Also, we
do know that we can not reverse what we have
already released into the oceans; we can only
look to the future. With this in mind, without
knowing anymore than we do about ocean acidification, it seems the answer is to bring emissions down and as close to zero as possible (Orr,
et. al., 2005).
STATE OF SCIENCE:
The saturation state of calcium carbonate in
the “business as usual” scenario of the IPCC is
undersaturated. Undersaturation of seawater,
which is the decrease in calcium saturation and
thus more acidic water, though still at pH levels
greater than 7.0, will likely occur within fifty
years in some polar and sub polar surface waters
(Orr, et. al., 2005). It is predicted that this
change in chemistry will occur most drastically
in the higher latitude oceans due to the presence
of seasonality in these areas as opposed to equatorial regions. In winter, the waters are cooled
and there is a higher amount of dissolved CO2.
Due to these factors, undersaturation of calcium
will occur in these waters first during winter. As
calcium binds with CO2, carbonic acid forms thus
making the water more acidic. However, this
process uses up the calcium in the water that
would be used to form and maintain the shells
and skeletons of marine calcifying organisms
such as pteropods and corals (Orr, et. al., 2005).
These species are critical to food webs and have
a difficult time migrating because in many cases,
they can survive only in specific habitats and the
availability of these habitats is lessening each
day.
Supporting research shows that through
analyzing aragonite and calcite saturation values
and quantifying calcium carbonate dissolution,
saturation horizons are migrating (Feely, et. al.,
2004). Results showed that in the southeastern
and northeastern Atlantic Ocean, the saturation
horizon for aragonite moved up between 80 and
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150 meters. In the Pacific Ocean, the horizon is
between 30 and 80 meters south of 38 degrees
south and between 30 and 100 meters north of 3
degrees north latitude (Feely, et. al., 2004).
Again, we see that the saturation horizon is becoming shallower in the higher latitude oceans.
This leaves much narrower spaces for species to
thrive and survive (Feely, et. al., 2004).
Climate change has caused three major
threats to the health of coral reefs. These include
ocean uptake of atmospheric carbon dioxide,
increased amount of hurricanes and warming
waters. Ocean uptake of CO2 leads to more
acidic waters which impede the ability of corals
to maintain and form their shells. Hurricanes
destroy corals with damaging currents. Warming
waters enable bleaching and disease among corals (Hughes, et. al., 2003).
One model assumes corals respond the
same to similar stresses and that corals can not
adapt to changes in temperature. This has been
questioned by noting that bleaching of corals is
patchy indicating that not all corals respond the
same to temperature or chemistry stressors
(Hughes, et. al., 2003).
In addition, bleaching has been thought to
be “adaptive”. However, it has been shown that
bleaching in corals is a response to environmental stressors such as warming, pH differences,
and chemistry differences rather than an adaptive
measure (Hughes, et. al., 2003).
Although it is unknown whether corals can
evolve to adapt to warming climates and changes
in ocean water chemistry, it may be possible and
further research must be conducted. Even if evolution can occur at such a quick rate, it is uncertain whether genetic traits will be inherited that
will enable corals to survive. Perhaps, if corals
evolve to be more tolerant of warmer temperatures, they will be less tolerant of higher pH values. These are considered life history tradeoffs.
It is impossible to know more about these tradeoffs without more studies and even then, the future is uncertain (Hughes, et. al., 2003).
PERSPECTIVES IN MEDIA AND PUBLIC
POLICY:
Elizabeth Kolbert’s, The Darkening Sea,
highlights the deteriorating shells of pteropods
while explaining sea water chemistry as the culprit for the disintegration. Kolbert relates that
anthropogenic emissions are the cause of the
trend toward more acidic ocean waters. She
shows how each of the IPCC emissions scenarios
lead ultimately to more acidic oceans because we
cannot reverse the process of carbon sequestration; we can only slow it down. She acknowledges that if the oceans did not sequester the
majority of the carbon dioxide that we emit, then
the earth would be at a heightened state of warming currently. This sequestration leaves us an
opportunity to reduce or aim for zero emissions
and create a lag to disrupt the rate of acidification. This will give us more time to research the
issue.
However, Kolbert does not address the
frightening reality that the oceans will only sequester a certain amount of carbon dioxide before they become saturated and are no longer to
buffer our emissions. At this point, which is
unidentified, the oceans will become a net source
of carbon (Kolbert, 2006). This occurs as the
oceans reach their capacity with how much carbon they can hold and begin to release carbon to
compensate. This release, coupled with our high
emissions, will increase the rate of warming and
climate change.
Perhaps the general media opinion was
aimed at giving people hope that with a zero
emissions policy, we may be able to counter the
damage we have created.
CONSIDERATIONS FOR POLICYMAKERS:
With all of this information, policymakers
should produce emissions management plans
with an end product of low-zero emissions. Efforts currently underway by governments include
laws and incentives for green lifestyles. Treaties
and voluntary carbon reduction programs are
beginning to show the world’s interest in reducing emissions. However, many of these efforts
are treating the symptom, not the problem. To
begin to give ourselves enough time, we must
implement a low emissions target. This notion is
justified by the IPCC in their IPCC S650 stable
rate emissions model versus their business as
usual model IPCC IS92a (IPCC, 2007).
Also, to help sustain corals, better management practices need to be implemented concerning no-take areas. The main threats to corals
are not mitigated by small no-take areas. Although no-take zones can not protect corals from
warming waters and ocean acidification, they can
protect them from direct human intervention.
These areas must encompass the majority of the
reefs they are meant to protect if they are to be
successful. However, without limiting emissions
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and giving corals an opportunity to evolve, migrate or adjust, there is little hope that no-take
areas alone will do the job (Hughes, et. al., 2003).
In addition to lowering emissions, funding
research to further the breadth of knowledge
concerning ocean water chemistry and impacts
on calcifying organisms is critical. Understanding the thresholds that exist in the ocean chemistry and within ecosystems will give us clues as to
how much time we have to make changes before
the oceans are only inhabitable by jellyfish and
the main buffer of our carbon emissions becomes
a source.
There are many social conflicts and technical uncertainties associated with reducing emissions. Will our society crash without fossil fuel
usage? If we plan accordingly to use our depleting natural resources to define a new society of
“green technology” in which emissions are drastically reduced, there is hope that the pace of
climate change will slow and the quality and
health of our environment will improve. In the
mean time, the delicate ecosystems of our oceans
are fighting to survive.
Abstract: The diversity, frequency, and
scale of human impacts on coral reefs are increasing to the extent that reefs are threatened
globally. Projected increases in carbon dioxide
and temperature over the next 50 years exceed
the conditions under which coral reefs have
flourished over the past half-million years. However, reefs will change rather than disappear entirely, with some species already showing far
greater tolerance to climate change and coral
bleaching than others. International integration
of management strategies that support reef resilience need to be vigorously implemented, and
complemented by strong policy decisions to reduce the rate of global warming.
IPCC, 2007: Summary for Policymakers. In:
Climate Change 2007: The Physical Science
Basis. Contribution of Working Group I to the
Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S.,
D. Qin, M. Manning,
Z. Chen, M. Marquis, K.B. Averyt,
M.Tignor and H.L. Miller (eds.)]. Cambridge
University Press, Cambridge, United Kingdom
and New York, NY, USA.
CITED REFERENCES WITH ABSTRACTS:
Kolbert, E. (2006). "The Darkening Sea."
The New Yorker 82(38).
Feely, R. A., C. L. Sabine, et al. (2004).
"Impact of anthropogenic CO2 on the CaCO3
system in the oceans." Science 305(5682): 362366.
Orr, J. C., V. J. Fabry, et al. (2005). "Anthropogenic ocean acidification over the twentyfirst century and its impact on calcifying organisms." Nature 437(7059): 681-686.
Abstract: Rising atmospheric carbon dioxide (CO2) concentrations over the past two centuries have led to greater CO2 uptake by the
oceans. This acidification process has changed
the saturation state of the oceans with respect to
calcium carbonate (CaCO3) particles. Here we
estimate the in situ CaCO3 dissolution rates for
the global oceans from total alkalinity and
chlorofluorocarbon data, and we also discuss the
future impacts of anthropogenic CO2 on CaCO3
shell forming species. CaCO3 dissolution rates,
ranging from 0.003 to 1.2 micromoles per kilogram per year, are observed beginning near the
aragonite saturation horizon. The total water
column CaCO3 dissolution rate for the global
oceans is approximately 0.5 +/- 0.2 petagrams of
CaCO3-C per year, which is approximately 45 to
65% of the export production of CaCO3.
Abstract: Today's surface ocean is saturated with respect to calcium carbonate, but increasing atmospheric carbon dioxide concentrations are reducing ocean pH and carbonate ion
concentrations, and thus the level of calcium
carbonate saturation. Experimental evidence
suggests that if these trends continue, key marine
organisms - such as corals and some plankton will have difficulty maintaining their external
calcium carbonate skeletons. Here we use 13
models of the ocean - carbon cycle to assess calcium carbonate saturation under the IS92a 'business-as-usual' scenario for future emissions of
anthropogenic carbon dioxide. In our projections,
Southern Ocean surface waters will begin to become undersaturated with respect to aragonite, a
metastable form of calcium carbonate, by the
year 2050. By 2100, this undersaturation could
extend throughout the entire Southern Ocean and
into the subarctic Pacific Ocean. When live pteropods were exposed to our predicted level of
undersaturation during a two-day shipboard ex-
Hughes, T. P., A. H. Baird, et al. (2003).
"Climate change, human impacts, and the resilience of coral reefs." Science 301(5635): 929933.
3
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periment, their aragonite shells showed notable
dissolution. Our findings indicate that conditions
detrimental to high-latitude ecosystems could
develop within decades, not centuries as suggested previously.
4
Changes to the Cryosphere
Brandon Murphy
EXECUTIVE SUMMARY
Changes to the frozen surfaces of the
earth provide some of the most visible evidence
of a shifting climate. Glaciers are shrinking
throughout the world, and the two largest ice
sheets, Greenland and Antarctica, are experiencing a negative mass balance of ice. This loss of
continental ice is contributing to the rise of sea
level. The loss of mass from inland glaciers is
occurring more rapidly than from the ice sheets,
and threatens both communities that depend of
them for sources of water and communities that
depend on them for sources of income.
Sea ice is steadily decreasing in extant
during summer at a rate of 4% per decade, which
will have a negative impact on those animals that
are adapted to living on it. The opening of Arctic waters also creates new opportunities for human economic gain through fishing, resource
extraction, and new trade routes. However, there
is the possibility that access and rights to these
waters may be a source of conflict in the future.
The loss of permafrost will affect human infrastructure as the ground subsides. The
loss of permafrost in peatlands may have positive and negative effects on the rate to climate
change. Peatlands are large storage pools of
carbon and many are located in permafrost regions. Depending on shifting climate patterns, at
least some areas may become carbon and radiative forcing sinks as they become more productive. However, there may be a lag in this effect
during which the peatland becomes a radiative
forcing source because of increased methane
production. If some of these thawing peatlands
also become drier because of changing climate,
then they will likely become sources of carbon.
INTRODUCTION
The cryosphere consists of all the frozen parts of the earth, such as glaciers, ice caps,
ice sheets, sea ice, and areas of land underlain by
permafrost. Recent warming trends associated
with anthropogenic climate charge are reducing
the extent of these frozen areas. There are many
implications associated with changes in the
cryosphere. The melting of large bodies of continental ice contributes to the rise of sea level. In
some areas, glacial melt is an important source of
water, and the potential loss of glaciers could
have dire consequences for the surrounding
populations. Changes in sea ice may have some
positive effects, such as opening new trade
routes, but also negative consequences for the
animals that live and depend on the ice. The loss
of permafrost can wreak human infrastructure as
the ground begins to subside, but may also cause
a shift in vegetation which can create a carbon
sink.
The melting of glaciers and ice caps is a
topic very commonly associated with global climate change. The recession of glacial terminal
ends, and the thinning of snow and ice pack are a
favorite visualization of the warming climate in
the media. The rise of sea level associated with
the glacial melt water to the is also a common
topic in the popular media, although in reality it
is a much smaller contributor to sea level rise
than the thermal expansion of water. Before
delving into any discussion on the cryosphere it
is helpful to clarify a few common (and often
interchanged) terms. The American Meteorological Society Glossary of Meteorology defines
a glacier as “a mass of land ice, formed by the
further recrystalization of firn (compacted, metamorphosed old snow), flowing continuously
from higher to lower elevations.” AMS defines
an ice cap as, “a dome-shaped perennial cover of
ice and snow over an extensive portion of the
earth’s surface.” AMS defines an ice sheet as, “a
continuous sheet of land ice that covers a very
large area and moves outward in many directions,” which is so thick that it will, “mask the
land surface contours.” In general, both ice caps
and ice sheets refer to bodies of ice so large that
they can cover mountains, and therefore flow
radially. The distinction is sometimes drawn at
50,000 km2 (19,300 mi2) between the smaller ice
cap and the larger ice sheet.
Permafrost consists of all the ground
that is frozen year round for at least two years.
Permafrost underlies about 24% of the Northern
Hemisphere’s land surface (Turetsky et al. 2007).
These northern climates also support substantial
peatlands. These northern peatlands are a substantial carbon pool, estimated to range from 42
to 489 Pg C (Turetsky et al. 2007), which represents 20-30% of all global soil C (Johansson et al.
2006). Concerns have been raised that as some
of these peatlands that have been frozen begin to
thaw, they will turn into carbon sources as the
peat decays. However, there is new evidence
that suggests that some of these peatlands will
not dry out when they thaw but instead increase
in productivity creating more carbon sinks
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(Camill et al. 2001; Johansson et al. 2006; Turetsky et al. 2007).
STATE OF THE SCIENCE
It is estimated that there may be as
many as 170,000 glaciers in the world, and of
them only about 300 have been studied for
changes in mass balance for any length of time
(Barry 2006). Only 50 or so of the 300 glaciers
have records going back more than 20 years.
There are a number of ways in which glaciers are
monitored. The most common has been changes
in the location of the glacial terminus. However,
the glacial terminus is not necessarily the best
representation of true changes in mass and volume of a glacier because glaciers may thin more
rapidly than they recede (Barry 2006).
There are three main techniques used to
calculate a mass balance (Rignot & Thomas
2002). The mass budget method is calculated
from estimates of all inputs and outputs to a glacier or ice sheet. Outputs include melt, sublimation, flow, calving, which are all dynamic processes. The uncertainties with all the estimations
of the inputs and outputs can lead to error in the
mass budget calculation, particularly on larger
areas of ice. The second method for mass balance is measurements of elevation change over
time. The changes in elevation can then be converted into estimates of changes in volume. The
changes in elevation are measured by laser altimetry from either satellites or aircraft, and must
first be corrected to account for isostatic rebound
of the earth’s surface. The third method of cal-
culating a mass balance involves measuring the
changes in weight of a body of ice by measuring
changes in the earth’s field of gravity using
NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites. The premise behind
the gravimetric technique is that the greater the
mass at any point on the earth, the stronger its
field of gravity. The measurements made by the
GRACE satellites need to be corrected for
isostatic rebound, atmospheric mass, and external signals from continental hydrology outside
the area being measured and ocean mass variability (Velicogna & Wahr 2006). The gravimetric technique, which only began in 2002, is particularly useful for calculating mass budget on
very large areas such as the Greenland ice sheet,
and the Antarctic ice sheet.
The calculation of mass budget for the
three main ice sheets from GRACE satellites’
data generally shows a net loss of ice in recent
years. The Greenland ice sheet had a total loss of
82 + 28 km3 ice per year from 2002-2004 (Velicogna & Wahr 2005). The West Antarctic ice
sheet had a loss of 148 + 21 km3 per year, and
the East Antarctic ice sheet had a change of 0 +
56 km3 per year from 2002-2005 (Velicogna &
Wahr 2006). There is a general consensus
among different mass balance techniques that
both Greenland and Antarctica are currently experiencing a net loss of ice (table 1)
Table 1. Summary of mass balance studies of the East Antarctic ice sheet (EAIS), West Antarctic ice sheet (WAIS), total Antarctic ice sheets (AIS), and the Greenland ice sheet (GIS)
(Shepherd & Wingham 2007).
2
While Greenland and Antarctica account
for the vast majority of the worlds ice, it is the
smaller continental glaciers that are melting
faster. Approximately 60% of the ice being lost
each year comes from small glaciers as opposed
to the ice sheets (Meier et al. 2007). These
smaller glaciers lack the thermal inertia of the ice
sheets.
The Artic sea ice is in a decline, primarily
in its extent during the summer months. Since
around 1960, the extent of summer ice has been
decreasing at about 4% per decade (Deser et al.
2000). While sea ice loss does not affect sea
level, it has important implications for animals
that are adapted to living on the ice.
There has been a concern that the loss of
permafrost in peatlands will cause the peat to dry
out and decompose in a warming climate, which
would contribute to large releases of CO2. However, Johansson et al. (2006) calculated a net
increase of 16% in the CO2 sink following thawing in a peatland. Despite the reduction in CO2,
it was estimated that the peatland would have a
net 47% greater radiative forcing on the atmosphere over a 100 year because of increased
methane production. Another study by Turetsky
et al. (2007), which looked at various stages of
thawing peatlands, found that the increase in
methane production would decrease over time,
such that the radiative forcing from the increase
methane might offset gains from CO2 sequestration for as much as 70 years, but eventually the
peatland becomes a net radiative forcing sink.
The new evidence that thawing peatlands may help offset anthropogenic increases in
radiative forcing is encouraging, but more research is necessary because there have been so
few studies experimentally looking at the question. With a changing climate it is unknown if
the effects will be consistent everywhere. It is
possible that in some areas, the warming may
also coincide with less precipitation and thawing
peatlands may dry out and decompose in these
areas thus contributing to greenhouse gas emissions.
PERSPECTIVES IN THE MEDIA AND PUBLIC
POLICY
The loss of sea ice and glaciers has been
a hot topic in the media for making the case of
global warming. Pictures of glaciers now versus
50 years ago make for dramatic evidence of a
warming climate. However, the implications for
people who depend on some of those glaciers for
water seems to be less commonly discussed.
However, it is this aspect that requires the greatest attention from policy makers, not just in addressing global warming, but also in planning for
the lack of water. It is unlikely that changes
made now to reduce greenhouse gas emissions
will be able to prevent many of these glaciers
from melting completely, so other plans must be
made now on how to keep the populations in
these regions supplied with water in order to
avoid a humanitarian crisis.
A somewhat less severe, but still problematic effect of the loss of glaciers will be the
collapse of local economies that depend upon
glaciers for tourism and recreation. The effects
may ripple through into the larger winter sports
industry as a whole as well.
The loss of sea ice is another poster
child for global climate change, particularly because of the wildlife associated it (Amos 2007;
Stuck 2007). Despite the negative implications
for wildlife, the loss of sea ice is also viewed to
have some positive consequences such as opening up new areas for fishing, exploration for oil
and gas, and new shipping routes (Stuck 2007).
However, the opening up of new water may lead
to further international conflict as countries debate who controls and has rights to these various
areas. Since most of the benefits from these new
open areas of have economic consequences, they
are all the more likely to result in conflicts.
IMPLICATIONS FOR POLICYMAKERS
The biggest implication for policymakers is to address the potential water shortages
that will occur as the glaciers recede and vanish,
while water is still available. This may involve
establishing some other water storage system,
enacting policies to enforce water use efficiency,
and limiting continued population growth in
these areas. It will be much easier to set up a
new system now and be prepared, than waiting
until the water runs out.
In regards to implications of the arctic
waters opening up, new international treaties
should be created regarding its access and use to
the areas to avoid future conflicts.
The implications of all the changes in
glaciers and sea ice enforce the point that new
policies are required to curb the continued anthropogenic contribution to global climate
change. Due to the visible nature of the losses of
ice, changes to the cryosphere has been a strong
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arguing point for change, however the cause
would be further helped by emphasizing the
negative impacts it may have on humans.
WORKS CITED WITH ABSTRACTS
American Meteorological Society. 2000.
Glossary of Meteorology, 2nd Edition.
http://amsglossary.allenpress.com.
Amos, J. 2006. Arctic sea ice 'faces rapid
melt'. in. BBC News.
Barry, R. G. 2006. The status of research
on glaciers and global glacier recession: a review.
Progress in Physical Geography 30:285-306.
Abstract: Mountain glaciers are key indicators
of climate change, although the climatic variables involved differ regionally and temporally.
Nevertheless, there has been substantial glacier
retreat since the Little Ice Age and this has accelerated over the last two to three decades.
Documenting these changes is hampered by the
paucity of observational data. This review outlines the measurements that are available, new
techniques that incorporate remotely sensed data,
and major findings around the world. The focus
is on changes in glacier area, rather than estimates of mass balance and volume changes that
address the role of glacier melt in global sealevel rise. The glacier observations needed for
global climate monitoring are also outlined.
Camill, P., J. A. Lynch, J. S. Clark, J. B.
Adams, and B. Jordan. 2001. Changes in biomass, aboveground net primary production, and
peat accumulation following permafrost thaw in
the boreal peatlands of Manitoba, Canada. Ecosystems 4:461-478.
Abstract: Permafrost
thaw resulting from climate warming may dramatically change the succession and carbon dynamics of northern ecosystems. To examine the
joint effects of regional temperature and local
species changes on peat accumulation following
thaw, we studied peat accumulation across a regional gradient of mean annual temperature
(MAT). We measured aboveground net primary
production (AGNPP) and decomposition over 2
years for major functional groups and used these
data to calculate a simple index of net annual
aboveground peat accumulation. In addition, we
collected cores from six adjacent frozen and
thawed bog sites to document peat accumulation
changes following thaw over the past 200 years.
Aboveground biomass and decomposition were
more strongly controlled by local succession
than regional climate. AGNPP for some species
differed between collapse scars and associated
permafrost plateaus and was influenced by regional MAT. A few species, such as Picea
mariana trees on frozen bogs and Sphagnum
mosses in thawed bogs, sequestered a disproportionate amount of peat; in addition, changes in
their abundance following thaw changed peat
accumulation. Pb-210-dated cores indicated that
peat accumulation doubles following thaw and
that the accumulation rate is affected by historical changes in species during succession. Peat
accumulation in boreal peatlands following thaw
was controlled by a complex mix of local vegetation changes, regional climate, and history.
These results suggest that northern ecosystems
may show responses more complex than large
releases of carbon during transient warming.
Deser, C., J. E. Walsh, and M. S. Timlin.
2000. Arctic sea ice variability in the context of
recent atmospheric circulation trends. Journal of
Climate 13:617-633.
Abstract: Forty years (1958-97) of reanalysis
products and corresponding sea ice concentration
data are used to document Arctic sea ice variability and its association with surface air temperature (SAT) and sea level pressure (SLP)
throughout the Northern Hemisphere extratropics.
The dominant mode of winter (January-March)
sea ice variability exhibits out-of-phase fluctuations between the western and eastern North Atlantic, together with a weaker dipole in the North
Pacific. The time series of this mode has a high
winter-to-winter autocorrelation (0.69) and is
dominated by decadal-scale variations and a
longer-term trend of diminishing ice cover east
of Greenland and increasing ice cover west of
Greenland. Associated with the dominant pattern
of winter sea ice variability are large-scale
changes in SAT and SLP that closely resemble
the North Atlantic oscillation. The associated
SAT and surface sensible and latent heat flux
anomalies are largest over the portions of the
marginal sea ice zone in which the trends of ice
coverage have been greatest, although the welldocumented warming of the northern continental
regions is also apparent. The temporal and spatial relationships between the SLP and ice anomaly fields are consistent with the notion that atmospheric circulation anomalies force the sea ice
variations. However, there appears to be a local
response of the atmospheric circulation to the
changing sea ice cover east of Greenland. Specifically, cyclone frequencies have increased and
mean SLPs have decreased over the retracted ice
margin in the Greenland Sea, and these changes
differ from those associated directly with the
4
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North Atlantic oscillation. The dominant mode
of sea ice variability in summer (July-September)
is more spatially uniform than that in winter.
Summer ice extent for the Arctic as a whole has
exhibited a nearly monotonic decline (-4% decade(-1)) during the past 40 yr. Summer sea ice
variations appear to be initiated by atmospheric
circulation anomalies over the high Arctic in late
spring. Positive ice-albedo feedback may account for the relatively long delay (2-3 months)
between the time of atmospheric forcing and the
maximum ice response, and it may have served
to amplify the summer ice retreat.
Johansson, T., N. Malmer, P. M. Crill, T.
Friborg, J. H. Akerman, M. Mastepanov, and T.
R. Christensen. 2006. Decadal vegetation
changes in a northern peatland, greenhouse gas
fluxes and net radiative forcing. Global Change
Biology 12:2352-2369.
Abstract: Thawing
permafrost in the sub-Arctic has implications for
the physical stability and biological dynamics of
peatland ecosystems. This study provides an
analysis of how permafrost thawing and subsequent vegetation changes in a sub-Arctic Swedish mire have changed the net exchange of
greenhouse gases, carbon dioxide (CO2) and
CH4 over the past three decades. Images of the
mire (ca. 17 ha) and surroundings taken with
film sensitive in the visible and the near infrared
portion of the spectrum, [i.e. colour infrared
(CIR) aerial photographs from 1970 and 2000]
were used. The results show that during this period the area covered by hummock vegetation
decreased by more than 11% and became replaced by wet-growing plant communities. The
overall net uptake of C in the vegetation and the
release of C by heterotrophic respiration might
have increased resulting in increases in both the
growing season atmospheric CO2 sink function
with about 16% and the CH4 emissions with
22%. Calculating the flux as CO2 equivalents
show that the mire in 2000 has a 47% greater
radiative forcing on the atmosphere using a 100year time horizon. Northern peatlands in areas
with thawing sporadic or discontinuous permafrost are likely to act as larger greenhouse gas
sources over the growing season today than a
few decades ago because of increased CH4 emissions.
Meier, M. F., M. B. Dyurgerov, U. K. Rick,
S. O'Neel, W. T. Pfeffer, R. S. Anderson, S. P.
Anderson, and A. F. Glazovsky. 2007. Glaciers
dominate Eustatic sea-level rise in the 21st century. Science 317:1064-1067.
Abstract: Ice
loss to the sea currently accounts for virtually all
of the sea-level rise that is not to ocean warming,
and about 60% of the ice loss is from glaciers
and ice caps rather than from two ice sheets. The
contribution of these smaller glaciers has accelerated over the past decade, in part due to
marked thinning and retreat of marineterminating glaciers associated with a dynamic
instability that is generally not considered in
mass-balance and climate modeling. This acceleration of glacier melt may cause 0.1 to 0.25
meter of additional sea-level rise by 2100.
Rignot, E., and R. H. Thomas. 2002. Mass
balance of polar ice sheets. Science 297:15021506. Abstract: Recent advances in the determination of the mass balance of polar ice
sheets show that the Greenland Ice Sheet is losing mass by near-coastal thinning, and that the
West Antarctic Ice Sheet, with thickening in the
west and thinning in the north, is probably thinning overall. The mass imbalance of the East
Antarctic Ice Sheet is likely to be small, but even
its sign cannot yet be determined. Large sectors
of ice in southeast Greenland, the Amundsen Sea
Embayment of West Antarctica, and the Antarctic Peninsula are changing quite rapidly as a result of processes not yet understood.
Shepherd, A., and D. Wingham. 2007. Recent sea-level contributions of the Antarctic and
Greenland ice sheets. Science 315:1529-1532.
Abstract: After a century of polar exploration,
the past decade of satellite measurements has
painted an altogether new picture of how Earth's
ice sheets are changing. As global temperatures
have risen, so have rates of snowfall, ice melting,
and glacier flow. Although the balance between
these opposing processes has varied considerably
on a regional scale, data show that Antarctica
and Greenland are each losing mass overall. Our
best estimate of their combined imbalance is
about 125 gigatons per year of ice, enough to
raise sea level by 0.35 millimeters per year. This
is only a modest contribution to the present rate
of sea-level rise of 3.0 millimeters per year.
However, much of the loss from Antarctica and
Greenland is the result of the flow of ice to the
ocean from ice streams and glaciers, which has
accelerated over the past decade. In both continents, there are suspected triggers for the accelerated ice discharge-surface and ocean warming,
respectively- and, over the course of the 21st
century, these processes could rapidly counteract
the snowfall gains predicted by present coupled
climate models.
5
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Struck, D. 2007. NOAA scientists say Arctic ice is melting faster than expected. Pages A06
in Washington Post.
Turetsky, M. R., R. K. Wieder, D. H. Vitt,
R. J. Evans, and K. D. Scott. 2007. The disappearance of relict permafrost in boreal north
America: Effects on peatland carbon storage and
fluxes. Global Change Biology 13:1922-1934.
Abstract: Boreal peatlands in Canada have harbored relict permafrost since the Little Ice Age
due to the strong insulating properties of peat.
Ongoing climate change has triggered widespread degradation of localized permafrost in
peatlands across continental Canada. Here, we
explore the influence of differing permafrost
regimes (bogs with no surface permafrost, localized permafrost features with surface permafrost,
and internal lawns representing areas of permafrost degradation) on rates of peat accumulation
at the southernmost limit of permafrost in continental Canada. Net organic matter accumulation
generally was greater in unfrozen bogs and internal lawns than in the permafrost landforms, suggesting that surface permafrost inhibits peat accumulation and that degradation of surface permafrost stimulates net carbon storage in peatlands. To determine whether differences in substrate quality across permafrost regimes control
trace gas emissions to the atmosphere, we used a
reciprocal transplant study to experimentally
evaluate environmental versus substrate controls
on carbon emissions from bog, internal lawn,
and permafrost peat. Emissions of CO2 were
highest from peat incubated in the localized permafrost feature, suggesting that slow organic
matter accumulation rates are due, at least in part,
to rapid decomposition in surface permafrost
peat. Emissions of CH4 were greatest from peat
incubated in the internal lawn, regardless of peat
type. Localized permafrost features in peatlands
represent relict surface permafrost in disequilibrium with the current climate of boreal North
America, and therefore are extremely sensitive to
ongoing and future climate change. Our results
suggest that the loss of surface permafrost in
peatlands increases net carbon storage as peat,
though in terms of radiative forcing, increased
CH4 emissions to the atmosphere will partially
or even completely offset this enhanced peatland
carbon sink for at least 70 years following permafrost degradation.
Velicogna, I., and J. Wahr. 2005.
Greenland mass balance from GRACE. Geophysical Research Letters 32. Abstract: We
use 22 monthly GRACE (Gravity Recovery and
Climate Experiment) gravity fields to estimate
the linear trend in Greenland ice mass during
2002-2004. We recover a decrease in total ice
mass of 82 +/- 28 km(3) of ice per year, consistent with estimates from other techniques. Our
uncertainty estimate is dominated by the effects
of GRACE measurement errors and errors in our
post glacial rebound (PG) correction. The main
advantages of GRACE are that it is sensitive to
the entire ice sheet, and that it provides mass
estimates with only minimal use of supporting
physical assumptions or ancillary data.
Velicogna, I., and J. Wahr. 2006. Measurements of time-variable gravity show mass
loss in Antarctica. Science 311:1754-1756.
Abstract: Using measurements of time-variable
gravity from the Gravity Recovery and Climate
Experiment satellites, we determined mass variations of the Antarctic ice sheet during 2002-2005.
We found that the mass of the ice sheet decreased significantly, at a rate of 152 +/- 80 cubic kilometers of ice per year, which is equivalent to 0.4 +/- 0.2 millimeters of global sea-level
rise per year. Most of this mass loss came from
the West Antarctic Ice Sheet.
Zwally, H. J., M. B. Giovinetto, J. Li, H. G.
Cornejo, M. A. Beckley, A. C. Brenner, J. L.
Saba, and D. H. Yi. 2005. Mass changes of the
Greenland and Antarctic ice sheets and shelves
and contributions to sea-level rise: 1992-2002.
Journal of Glaciology 51:509-527. Abstract:
Changes in ice mass are estimated from elevation
changes derived from 10.5 years (Greenland) and
9 years (Antarctica) of satellite radar altimetry
data from the European Remote-sensing Satellites ERS-1 and -2. For the first time, the dH/dt
values are adjusted for changes in surface elevation resulting from temperature-driven variations
in the rate of firn compaction. The Greenland ice
sheet is thinning at the margins (-42 +/- 2 Gt a(-1)
below the equilibrium-line altitude (ELA)) and
growing inland (+53 +/- 2 Gt a(-1) above the
ELA) with a small overall mass gain (+11 +/- 3
Gt a(-1); -0.03 mm a(-1) SLE (sea-level equivalent)). The ice sheet in West Antarctica (WA) is
losing mass (-47 +/- 4 Gt a(-1)) and the ice sheet
in East Antarctica (EA) shows a small mass gain
(+16 +/- 11 Gt a(-1)) for a combined net change
of -31 +/- 12 Gt a(-1) (+0.08 mm a(-1) SLE).
The contribution of the three ice sheets to sea
level is +0.05 +/- 0.03 mm a(-1). The Antarctic
ice shelves show corresponding mass changes of
-95 +/- 11 Gt a(-1) in WA and +142 +/- 10 Gt a(1) in EA. Thinning at the margins of the
Greenland ice sheet and growth at higher eleva6
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tions is an expected response to increasing temperatures and precipitation in a warming climate.
The marked thinnings in the Pine Island and
Thwaites Glacier basins of WA and the Totten
Glacier basin in EA are probably ice-dynamic
responses to long-term climate change and perhaps past removal of their adjacent ice shelves.
The ice growth in the southern Antarctic Peninsula and parts of EA may be due to increasing
precipitation during the last century.
7
Global Circulation Models
Anna Lumsden
EXECUTIVE SUMMARY
Global circulation models are computer
model representations of the earth’s climate
system. They are used to estimate the impacts of
anthropogenic influences on future climate, most
commonly global mean temperatures. As these
models have become more sophisticated the
results they generate are subject to greater
uncertainty because the number of parameters
which are estimated has increased. Although
there is agreement among models that global
temperature will rise in the next three decades
regardless of emission policies, the complexity
of these models and the uncertainties inherent in
them have led to a generally apathetic view of
climate models in the media, and equivocating
on the part of some governments to commit to
radical changes in policy to deal with the causes
of global warming.
INTRODUCTION
“Model experiments show that
even if all radiative forcing agents1 are
held constant at year 2000 levels, a
further warming trend would occur in
the next two decades at a rate of about
0.1oC per decade, due mainly to the
slow response of the oceans. About
twice as much warming (0.2oC per
decade) would be expected if emissions
are within the rage of the SRES
scenarios. Best-estimate projections
from models indicate that decadalaverage warming over each inhabited
continent by 2030 is insensitive to the
choice among SRES scenarios and is
very likely to be at least twice as large
as the corresponding model-estimated
natural variability during the 20th
century” (IPCC 2007)
The predictions of warming made by the
Inter-governmental Panel on Climate Change
(IPCC) are based on global circulation models
(GCMs). GCMs, which have their origins in
weather forecasting, are a combination of
atmospheric, ocean, and terrestrial models;
coupled together to create a computer model
representation of the earth’s climate (Houghton
2004). In the above quotation, the IPCC climate
scientists have used GCMs to predict the effects
of different Special Report on Emission
Scenarios 2 (SRES) to determine a range of
warming possibilities over the next two decades.
In this paper I will briefly outline the
composition of a climate model, review the
current scientific literature, the perspectives of
GCMs in the media, and how climate model
results are implemented by policy makers. The
focus here will not be on the predictions that
climate models make, but the uncertainties
inherent in those predictions and how these are
perceived by the public and policy makers, it at
all.
The first climate model 3 was a simulation
of the circulation patterns of the atmosphere in
1949 (Flannery 2005). Since then, GCMs have
increased in complexity, and also model the
terrestrial and oceanic components of the climate
system, and the interactions and feedbacks
within and between these systems, and the
atmosphere. These interactions and feedbacks
are modeled based on what scientists know about
the physical processes, such as the conservation
of energy, and parameters within the climate
system. Models can have hundreds of parameters
which could include: horizontal and vertical
movement of air or water, the amount of
incoming solar radiation or the concentration of a
certain atmospheric gas. To model these physical
processes and parameters, the atmosphere and
the ocean are divided into three-dimensional
grids. In addition to correct parameterization of
processes, the cloud-radiation, water vapor,
ocean-circulation, and ice-albedo feedbacks
within the system must be modeled as well.
Decades of research and data accumulation
have evolved into three uses for GCMs. One, to
model past climatic change; second, to model the
current climate and weather patterns; and third,
to model the future climate. The ability of a
climate model to accurately depict past and
current climate, to predict the effects of natural
disasters on the system (e.g. a volcanic eruption),
and to accurately depict the physical processes
2
1
Radiative forcing is a measure of the influence that a
climatic factor, such as cloud cover, has on the balance of
incoming and outgoing energy. Positive forcing warms the
earth’s surface, and negative forcing cools it (IPCC 2007)
The SRES scenarios represent four different combinations
of global population and economic growth, and energy types
and consumption.
3
In this paper GCMs and climate model are used
interchangeably.
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within the climate system are an indication of its
credibility (Flannery 2005, Houghton 2004).
This in turn leads to greater confidence in the
predictions of GCMs.
Over time, as the processing power of
computers has increased and uncertainties in
computer programming have reduced, the
uncertainty from the inclusion of real world
parameters has increased, as the number of
parameters has increased. A good example of
this is the recent inclusion of seal level pressure
into model parameters (Flannery 2005). These
uncertainties arise because each parameter is
estimated and averaged for each grid cell, and
are dependent upon the particulars of the GCM
used. This means that each climate model will
produce different outputs for combinations of
parameters. As GCMs are used mainly to
forecast how anthropogenic effects on the
climate system will lead to atmospheric warming,
the range in possible outputs which can be
produced has lead to debate in the scientific
literature and within the media and public as to
which results are important.
STATE OF THE SCIENCE
therefore they give a more representative idea of
possible impacts and outcomes for the particular
scenario being investigated (Murphy et al. 2004,
Dettinger 2005, Stainforth et al. 2005). Some
authors have suggested that even the most
sophisticated GCM will provide only limited
knowledge on the possible impacts of warming,
therefore only large ensembles of climate models
should be used to determine a range of impacts
and estimate uncertainty (Murphy et al. 2004,
Dettinger 2005).
Work by Stainforth et al. (2005), which
used the novel approach of running over 2000
different simulations using the downtime on
personal computers, aimed to estimate
uncertainty by changing groups of parameters in
the GCMs. Each of these parameter groups
created an ensemble, which were then combined
to create a grand ensemble to estimate model
sensitivity, or the response of global mean
temperature to doubled levels of atmospheric
CO2 (Stainforth et al. 2005). The conclusions of
the work were that this grand ensemble produced
a wide range of sensitivities, with uncertainty
increasing with the number of parameters
perturbed (Stianforth et al. 2005).
Uncertainty arises from at least four
sources. One, is that the range of parameters
which are used for each model are different; two,
the choice of emission scenario; three, structural
uncertainty, where models do not necessarily
depict climate processes accurately e.g.
feedbacks or non-linear change; and four,
inherent climate variability (Zwiers 2002;
Dettinger 2005, Stainforth et al. 2005). The
uncertainties inherent in the generation of
climate models are evident in the trend of recent
scientific publications, which have focused on
how to quantify these model uncertainties, and
relative importance of the range of predictions
produced.
This work determined that extreme
sensitivity values cannot be ignored because they
are indicators of model shortcomings, and
therefore where research resources should be
allocatedm in order to improve parameter values
(Stainforth et al. 2005). A study by Zhang et al.
(2007) focusing on the difference between
modeled estimates versus observed changes in
precipitation indicated that ensemble simulations
tended to underestimate regional precipitation
changes, and with wide ranges in uncertainties
which varied with latitude. These results suggest
that more research resources need to be allocated
towards fine tuning model parameters.
Acknowledging the variability in results
which occur due to using different climate
models, the consensus of the scientific
community has been to run a number of
simulations on different models, by perturbing
model parameters, and then comparing the
results. These ensembles 4 produce a range of
responses for a number of different models,
PERSPECTIVES IN THE MEDIA AND PUBLIC
POLICY
4
“An ensemble is a collection of predictions; each prediction
is different from the others due to some prescribed change in
the model condition, such as model: constructions, initial
conditions or future emissions of greenhouse gasses into the
global atmosphere” (Dettinger 2005)
It is clear that GCMs are the main
information source for planners about future
warming trends; therefore their relative
forecasting abilities are important to the climate
change debate (Murphy et al 2004). However,
the science behind GCMs is so complex that I
would venture to say that the lay person would
not be able to interpret the statistical analyses
that go into determining not only what are the
important parameters driving temperature
increases, but also the range of temperatures,
2
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sensitivities and uncertainties produced. It is
therefore up to climate scientists to interpret
these values for the public, and policy makers.
A good example of scientific interpretation
for the media and public are the IPCC
Assessment Reports. These reports are readily
available, and are geared towards guiding policy
makers in the decisions they have to make about
country s’ climate change and energy usage
policies. The IPCC reports tend to remove the
technical details and focus on the trends which
the climate models display. The IPCC references
the climate models which generate their results
in a fairly cursory manner (see opening quote),
without going into detail about the science
behind the GCMs used.
2050. Therefore if all emissions of greenhouse
gases were to cease now, it would take until
2050 for the climate to stabilize (Zwiers 2002,
Flannery 2005). One problem is that warming is
often predicted to the 2100’s; this is far beyond
the range of typical policy development and
possible mitigation strategies (Zwiers 2002).
Although these temporal ranges are useful for
looking at the differences in predictions between
models, it tends to obscure the general agreement
about the certain warming of the next few
decades (Zwiers 2002).
Globally, many countries ratified the Kyoto
Protocol in 2005, with the exception of the US
and Australia. This law was to bind the 146
countries that signed to cut their combined
emissions to 5% below 1990 levels by 2008 to
2012 (bbc.oc.uk. 2005) In the United States in
July 2007, President Bush put forward a “postKyoto framework on energy security and climate
change by 2008” (state.gov 2007). This
framework is designed to implement near term
domestic policies to reduce green house gas
emissions by 18% by 2012. This would include
programs such as Energy Star, domestic methane
programs, and increasing the fuel economy of
vehicles by using alternative and renewable fuels.
These domestic policies are in addition to the
billions of dollars in research and design which
have been invested into reducing green house
gases.
Similarly the complexity of the issue does
not lend itself to discussion in the popular media.
For example US Today, the most widely read
newspaper in the US, has a readership of 5.4
million, 2.5 print (Marketwatch.com, 2007). A
search on their website of keywords “climate
models” returned 59 search results from 1987 to
the present, 32 of which occurred since
December 20th 2005 (usatoday.com 2007).
Compare these results with a search of “Paris
Hilton” for the same time period and 305 results
are returned. This, I believe is an indication of a
combination of possibilities. Either, that the
scientific community has not expressed the
importance of climate models to the public,
therefore enabling an apathetic attitude; or the
topic is simply too complex for reporters to
interpret and engage with the public; or the
media is responding to a low desire by the public
to engage with the issue.
Despite this seeming commitment
addressing climate change, in response to
IPCC’s final assessment report issued
November 17th 2007, the NY Times had
analysis of the administration’s response:
According to a BBC.com poll (September
2007), 80% of the public believes that climate
change is as the result of anthropogenic forcing.
If this is the common public opinion, then
perhaps it is not necessary to have a discourse
about GCMs in the public sphere. What may be
more important is that the trends which have
been observed in these data and agreed upon by
the scientific community are translated into
public policy.
“Despite the report’s added
emphasis on a list of “reasons for
concern” about the continuing growth
of long-lived emissions that trap heat,
senior White House officials said
Friday and Saturday that it remained
impossible to define a “dangerous”
threshold in the concentration of
greenhouse
gases
or
resulting
warming.” (NY Times 2007)
CONSIDERATIONS FOR POLICY MAKERS
Despite the uncertainties inherent in climate
science, all GCMs agree that warming will
continue, and for the range of the next 20 to 30
years. Climate models agree on the amplitude of
change, because the effects of this CO2 which is
already in the atmosphere will not be felt until
to
the
on
this
Although it is probably not necessary to
define “dangerous threshold in the concentration
of greenhouse gases or resulting warming”, some
might say that the uncertainty inherent in GCMs
has been used to equivocate about a serious
commitment to the implementation of drastic
policy changes to reduce the concentrations of
greenhouse gases expelled into the atmosphere.
3
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In short, U.S. policy makers seem yet to be
convinced that although there are a range of
possibilities in results from GCMs, the
agreement in the scientific community and the
public is that climate warming is not uncertain,
and that policy needs to be implemented to
curtail its effects.
Flannery, T. 2005. The weather makers:
how man is changing the climate and what it
means for life on earth. Atlantic Monthly Press
New York, NY
REFERENCES
IPCC Summary for Policy Makers. 2007.
In Climate Change 2007: The physical science
basis. Contribution of Working Group I to the
Fourth
Assessment
Report
of
the
Intergovernmental Panel on Climate Change
Solomon, S., Qin, D., Manning M., Chen, Z.,
Marquis, M., Avery, K.B., Tignor, M., Miller,
H.L. (eds.). Cambridge University Press,
Cambridge, United Kingdom and New York, NY,
USA.
Bbc.co.uk. Man causing climate change.
September
25,
2005.
http://search.bbc.co.uk/cgibin/search/results.pl?q
=climate+change+poll&go.x=0&go.y=0&go=go
&edition=i. Accessed November 19th 2007.
Bbc.co.uk. Q&A the Kyoto protocol. 16
February
2005.
http://news.bbc.co.uk/2/hi/science/nature/426992
1.stm Accessed November 19th 2007.
Dettinger, M.D. 2005. From climatechange spaghetti to climate-change distributions
for 21st century California. San Francisco
Estuary and Watershed Science 3 (1) Article 4, 1
– 14
The uncertainties associated with climatechange projections for California are unlikely to
disappear any time soon, and yet important longterm decisions will be needed to accommodate
those potential changes. Projection uncertainties
have typically been addressed by analysis of a
few scenarios, chosen based on availability or to
capture the extreme cases among available
projections. However, by focusing on more
common projections rather than the most
extreme projections (using a new resampling
method), new insights into current projections
emerge: (1) uncertainties associated with future
greenhouse-gas emissions are comparable with
the differences among climate models, so that
neither source of uncertainties should be
neglected or underrepresented; (2) twenty-first
century temperature projections spread more,
overall, than do precipitation scenarios; (3)
projections of extremely wet futures for
California are true outliers among current
projections; and (4) current projections that are
warmest tend, overall, to yield a moderately drier
California, while the cooler projections yield a
somewhat wetter future. The resampling
approach applied in this paper also provides a
natural opportunity to objectively incorporate
measures of model skill and the likelihoods of
various emission scenarios into future
assessments.
Houghton, John. 2004. Global warming the
complete briefing. Cambridge University Press.
3rd Edition.
Marketwatch.com November 15, 2007.
USA TODAY remains the most widely read
newspaper
in
the
United
States.
http://www.marketwatch.com/news/story/usatoday-remains-mostwidely/story.aspx?guid=%7B52FE1518-B2D84AD4-BBCF-FAC3A73EA43B%7D Accessed
November 19th 2007
Murphy, J.M., Sexton, D.H.M., Barnett,
D.N., Jones, G.S., Webb, M.J., Collins, M.,
Stainforth, D.A. 2004. Quantification of
modeling uncertainties in a large ensemble of
climate change simulations. Nature 430, 768 –
772
Abstract: Comprehensive global climate
models1 are the only tools that account for the
complex set of processes which will determine
future climate change at both a global and
regional level. Planners are typically faced with a
wide range of predicted changes from different
models of unknown relative quality2,3, owing to
large but unquantified uncertainties in the
modelling process4. Here we report a systematic
attempt to determine the range of climate
changes consistent with these uncertainties,
based on a 53-member ensemble of model
versions constructed by varying model
parameters. We estimate a probability density
function for the sensitivity of climate to a
doubling of atmospheric carbon dioxide levels,
and obtain a 5–95 per cent probability range of
2.4–5.4 8C. Our probability density function is
constrained by objective estimates of the relative
reliability of different model versions, the choice
of model parameters that are varied and their
uncertainty ranges, specified on the basis of
4
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expert advice. Our ensemble produces a range of
regional changes much wider than indicated by
traditional methods based on scaling the
response patterns of an individual simulation5,6
Stainforth, D. A., Aina, T., Christensen, C.,
Collins, M., Faull, N., Frame, D. J.,
Kettleborough, J. A., Knight, S., Martin, A.,
Murphy, J. M, Piani, C., Sexton, D., Smith, L. A.,
Spicer, R. A., Thorpe, A. J., Allen, M. R. 2005.
Uncertainty in predictions of the climate
response to rising levels of greenhouse gases.
Nature 433, 403 – 406
The range of possibilities for future climate
evolution1–3 needs to be taken into account
when planning climate change mitigation and
adaptation strategies. This requires ensembles of
multidecadal simulations to assess both chaotic
climate variability and model response
uncertainty4–9. Statistical estimates of model
response uncertainty, based on observations of
recent climate change10–13, admit climate
sensitivities—defined as the equilibrium
response of global mean temperature to doubling
levels of atmospheric carbon dioxide—
substantially greater than 5K. But such strong
responses are not used in ranges for future
climate change14 because they have not been
seen in general circulation models. Here we
present results from the ‘climateprediction.net’
experiment, the first multi-thousand-member
grand ensemble of simulations using a general
circulation model and thereby explicitly
resolving regional details15–21. We find model
versions as realistic as other state-of-the-art
climate models but with climate sensitivities
ranging from less than 2K to more than 11 K.
Models with such extreme sensitivities are
critical for the study of the full range of possible
responses of the climate system to rising
greenhouse gas levels, and for assessing the risks
associated with specific targets for stabilizing
these levels.
U.S. Department of State 2007. USA:
Energy needs, clean development and climate
change.
http://www.state.gov/documents/organization/90
174.pdf. Accessed November 19th 2007
Human influence on climate has been
detected in surface air temperature1–5, sea level
pressure6, free atmospheric temperature7,
tropopause height8 and ocean heat content9.
Human-induced changes have not, however,
previously been detected in precipitation at the
global scale10–12, partly because changes in
precipitation in different regions cancel each
other out and thereby reduce the strength of the
global average signal13–19. Models suggest that
anthropogenic forcing should have caused a
small increase in global mean precipitation and a
latitudinal redistribution of precipitation,
increasing precipitation at high latitudes,
decreasing
precipitation
at
sub-tropical
latitudes15,18,19, and possibly changing the
distribution of precipitation within the tropics by
shifting the position of the Intertropical
Convergence Zone20. Here we compare
observed changes in land precipitation during the
twentieth century averaged over latitudinal bands
with changes simulated by fourteen climate
models. We show that anthropogenic forcing has
had a detectable influence on observed changes
in average precipitation within latitudinal bands,
and that these changes cannot be explained by
internal climate variability or natural forcing. We
estimate that anthropogenic forcing contributed
significantly to observed increases in
precipitation in the Northern Hemisphere midlatitudes, drying in the Northern Hemisphere
subtropics and tropics, and moistening in the
Southern Hemisphere subtropics and deep
tropics. The observed changes, which are larger
than estimated from model simulations, may
have already had significant effects on
ecosystems, agriculture and human health in
regions that are sensitive to changes in
precipitation, such as the Sahel.
Zwiers, Francis W. 2002. The 20-year
forecast. Nature 416, 690 – 691
Policy-makers need short-term climate
predictions to develop strategies for coping with
climate change over the typical two-decade
planning horizon. Two new studies increase our
confidence in these predictions.
Zhang, X., Zwiers, F.W., Gegerl, G.C.,
Lambert, F.H., Gillett, N.P., Solomon, S., Stott,
P.A., Nozawa, T. 2007. Detection of human
influence on twentieth-century precipitation
trends. Nature 448, 461 – 465
5
Impact on freshwater resources
Nidhi Pasi
EXECUTIVE SUMMARY
Water is indispensable to all life and to
human activities. The impacts of the climate
change on freshwater resources are mainly due to
observed increases in temperature (land and sea
surface), sea level and precipitation variability.
These impacts will be compounded by factors
like population growth and current management
practices. A significant percentage of population
already exists in water stress regions. The adaptive practices, management and planning will
determine the impacts of global warming on
freshwater resources and their sustainable use/
development.
INTRODUCTION:
Water is indispensable to all forms of life
and is needed for almost all human activities.
Historically, civilizations have flourished along
or around the sources of water. Rivers have supported life and have been a source of communication. History is replete with examples of civilizations that have withered and vanished when
water became scarce. The global freshwater
availability is finite. However, with pressure of
ever increasing human population, demand for
direct human consumption, for food production
and consequent development and industrial processes on water resources are ever increasing. The
UN Comprehensive Assessment of freshwater
resources estimated that about one third of the
world’s population withdrawing more than 20%
of the their available water resources are deemed
to be suffering with water stress (Kundzewicz,
Z.W et all 2007). Moreover, it has been estimated that people living in conditions of acute
water shortage will increase from present figure
of 470 million to around 3000 million in 2025
(Vombatkere, Sudhir 2004) representing twothirds of world population. Human activities
affect freshwater resources in terms of both quality and quantity. Due to complex interconnections between climate and freshwater ecosystems,
any change affects both mean states and variability. In addition, spatial variations in the distribution of this prime natural resource have led to
formation of “water surplus” and “water deficit”
regions. Water scarcity leads to regional imbalances in terms of socio-economic development
and such imbalances are detrimental to sustain-
able development and adversely affect human
rights.
STATE OF THE SCIENCE
Flannery (2006) mentions that for every
degree increase in global temperature, the world
experiences one percent increase in rainfall.
However, this increase is not evenly distributed
in time and space leading to unusual patterns.
World rainfall in increasing over large parts and
more rain is falling at high altitudes in winter
leading to disastrous consequences. Also increases in winter rains in the southern part of the
hemisphere is affecting agriculture and increasing extreme weather events (like flooding, avalanches etc.). At the same time certain regions
are being tipped into a perpetual rain deficit potentially developing new Saharas. He talks about
the evidence of the shift to a newer drier climate
in Africa’s Sahel region, where models have
showed that rising sea temperature over the Indian Ocean due to accumulation of greenhouse
gases resulted in rainfall decline.
Arnell (2004) further talks about the relative effects of climate change and population
growth on the future global water resources
stresses using the special report on emission scenarios (SRES). The author estimates population
at risk by determining annual runoff (surplus/
deficit) using a macro-scale hydrological model,
monthly precipitation data downscaled to watershed and population estimates. It has been estimated that in absence of climate change the
number of people living in water stressed regions
will depend upon the population scenarios and
about 40% of world population in 2025 will be
water stressed. However, with climate change,
decreased runoff increases water stress in some
parts of the world like Mediterranean, central
and southern Africa, America and parts of
Europe. At the same time, increases in runoff in
wet seasons in certain parts of the world like
Southern and eastern Asia, may not be beneficial
as this leads to flood. The analysis also shows
that the impacts of the changes (in terms of
population and emission scenarios) will also depend on how water resources are managed in the
future.
PERSPECTIVES IN THE MEDIA AND PUBLIC
POLICY
Climate change effects on freshwater systems are often termed as the “other” water problem in the media (Gertner, Jin 2007) because
PASI FRESHWATER RESOURCES
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global warming has been more commonly linked
with rise in the sea level and submergence of the
coastal cities. However, steady melts of the
mountain snow packs and the loss of the deep
accumulated high latitude snow is a reality which
may just lead to lead to many challenges and
uncertainties.
The working group II third assessment report summarizes apparent trends (both increase
and decrease) in stream water volume, with peak
flows likely to move to winter from spring due to
early snowmelt. The glacier retreat will continue.
Moreover the magnitude and frequency of floods
is likely to increase and at the same time volumes of low flows will decrease in many regions
(NOAA- GDLF 2007).
The water quality degradation is likely to
be degraded due to high temperatures. With the
higher temperatures, increased intensity of precipitation and shifts in time of peak flow will
further worsen many forms of water pollution.
The pollutants may include sediments, nutrients,
dissolved organics, pathogens, pesticides, salt
and thermal pollution. This will impact the ecosystems, human health and operation costs of
current water treatment and infrastructure systems.
et all 2006) and long term potential sustainable
development of freshwater resources..
REFERENCES
1) Flannery, Tim (2005). Liquid Gold:
changes in rainfall. Chapter 13: The
weather makers: how man is changing the
climate and what it means for life on earth.
Atlantic Monthly Press : New York
2)
NOAA- GDLF (2007). National Oceanic
and
Atmospheric
Administration
Geophysical Fluid Dynamics Laboratory
Climate modeling research highlights. Will
the wet get wetter and the dry drier? Vol 1,
No.5,
February
2007.
http://www.gfdl.noaa.gov/research/climate/
highlights/PDF/GFDLhighlight_Vol1N5.pdf
3)
Kundzewicz, Z.W., L.J. Mata, N.W. Arnell,
P. Döll, P. Kabat, B. Jiménez, K.A. Miller,
T. Oki, Z. Sen and I.A. Shiklomanov
(2007). Freshwater resources and their
management. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth
Assessment Report of the Intergovernmental Panel on Climate Change. M.L. Parry,
O.F. Canziani, J.P. Palutikof, P.J. van der
Linden and C.E. Hanson, Eds., Cambridge
University Press, Cambridge.
4)
Gertner, Jin. (2007) The future is drying up.
New York Times. October 21 2007.
http://query.nytimes.com/gst/fullpage.html?
res=9C0CEFDA103CF932A15753C1A961
9C8B63
5)
Vombatkere, Sudhir (2004). Interlinking
National Rivers: to link or not to link? In:
Patekar, Medha, River Linking: a Millennium Folly?: Maharashtra, National Alliance of People’s Movement.
6)
Arnell, Nigel W. (2004). Climate change
and global water resources: SRES emissions and socio-economic scenarios. Global
Economic Change. Vol.14:31-55 In 1995,
nearly 1400 million people lived in waterstressed watersheds (runoff less than
1000m3/capita/year), mostly in south west
Asia, the Middle East and around the Mediterranean. This paper describes an assessment of the relative effect of climate
change and population growth on future
global and regional water resources stresses,
CONSIDERATIONS FOR POLICYMAKERS
Many current rivers originate in the glacier
regions (particularly in the Hindu Kush Himalalyan region and sustaining the highly populated countries of India and China) and are sustained by the summer season glacier melt. Global
warming will lead to glacier retreat with increased river flows (floods) in short terms and
gradual decline (water scarcity, stress and
drought) in flow over the next decades.
The decision makers within the countries
need to realize that the current water management practices are very likely going to be inadequate to reduce the negative impacts of climate
change on water supply reliability, flood risk and
health concerns. There need to be a continuous
evolution of management systems, as the unmanaged ones are likely to be most vulnerable.
The impacts will also depend upon a particular
freshwater system characteristic. The adverse
effects of climate on freshwater systems may be
further increased by the intensity of other
stresses like population growth. Hence there is a
need to incorporate the climate change variability into the water management and planning
which could help in better adaptation (Mall, R.K.
2
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using SRES socio-economic scenarios and
climate projections made using six climate
models driven by SRES emissions scenarios. River runoff was simulated at a spatial
resolution of 0.5_0.5_ under current and future climates using a macro-scale hydrological model, and aggregated to the watershed scale to estimate current and future
water resource availability for 1300 watersheds and small islands under the SRES
population projections. The A2 storyline
has the largest population, followed by B2,
then A1 and B1 (which have the same
population). In the absence of climate
change, the future population in waterstressed watersheds depends on population
scenario and by 2025 ranges from 2.9 to 3.3
billion people (36–40% of the world’s
population). By 2055 5.6 billion people
would live in water-stressed watersheds
under the A2 population future, and
‘‘only’’ 3.4 billion under A1/B1. Climate
change increases water resources stresses in
some parts of the world where runoff decreases, including around the Mediterranean, in parts of Europe, central and southern America, and southern Africa. In other
water-stressed parts of the world— particularly in southern and eastern Asia—climate
change increases runoff, but this may not
be very beneficial in practice because the
increases tend to come during the wet season and the extra water may not be available during the dry season. The broad geographic pattern of change is consistent between the six climate models, although
there are differences of magnitude and direction of change in southern Asia. By the
2020s there is little clear difference in the
magnitude of impact between population or
emissions scenarios, but a large difference
between different climate models: between
374 and 1661 million people are projected
to experience an increase in water stress.
By the 2050s there is still little difference
between the emissions scenarios, but the
different population assumptions have a
clear effect. Under the A2 population between 1092 and 2761 million people have
an increase in stress; under the B2 population the range is 670–1538 million, respectively. The range in estimates is due to the
slightly different patterns of change projected by the different climate models. Sensitivity analysis showed that a 10% variation in the population totals under a story-
line could lead to variations in the numbers
of people with an increase or decrease in
stress of between 15% and 20%. The impact of these changes on actual water
stresses will depend on how water resources are managed in the future.
7)
Mall, R.K., Akhilesh Gupta, Ranjeet Singh,
R. S. Singh and L. S. Rathore (2006) Water
resources and climate change: An Indian
perspective. Current Science, Vol. 90, No.
12: 1610- 1626 In recent times, several
studies around the globe show that climatic
change is likely to impact significantly
upon freshwater resources availability. In
India, demand for water has already increased manifold over the years due to urbanization, agriculture expansion, increasing population, rapid industrialization and
economic development. At present,
changes in cropping pattern and land-use
pattern, over-exploitation of water storage
and changes in irrigation and drainage are
modifying the hydrological cycle in many
climate regions and river basins of India.
An assessment of the availability of water
resources in the context of future national
requirements and expected impacts of climate change and its variability is critical for
relevant national and regional long-term
development strategies and sustainable development. This article examines the potential for sustainable development of surface
water and groundwater resources within the
constraints imposed by climate change and
future research needs in India..
3
Carbon Sinks and Sequestration
Ken Hubbard
EXECUTIVE SUMMARY
Quantification of carbon sources and sinks
is an essential part of determining long term anthropogenic impacts to global climate change.
Carbon is continually emitted to the atmosphere
in the form of carbon dioxide (CO2) as a byproduct of many processes such as combustion of
fossil fuels, biomass burning and land use
changes. Increased concentration of CO2 in the
atmosphere contributes to the “Greenhouse Effect”. The use of terrestrial carbon sinks as a
means of sequestering atmospheric CO2 has been
studied recently. Carbon can be removed from
the atmosphere by terrestrial vegetation, captured
and stored in geologic formations and captured
and transported for geologic storage. The uncertainties surrounding these different forms of terrestrial carbon sequestration warrant further investigation. Experiments have been conducted
in order to model plant response to increased
CO2 concentration. The length of time these
reservoirs can store the carbon, the efficiency of
carbon capture and storage, saturation limits of
the reservoirs and response to changes in climatic variables are all issues requiring further
research to determine the feasibility of terrestrial
sequestration.
INTRODUCTION
Carbon compounds are a major constituent of all living and non-living components
of the Earth. All life forms on the planet are
built around carbon based structures. In addition
to living organisms, substantial amounts of carbon are allocated to non-living things such as
rocks, sediments, oceans and dead and decaying
organic matter. Carbon, in the form or carbon
dioxide (CO2), is emitted naturally to the atmosphere as a byproduct of aerobic respiration, fires,
rotting of wood and decaying of other organic
matter in soils (Houghton, 2004). Carbon emitted to the atmosphere by natural means is offset
by the process of photosynthesis, in which plants
uptake CO2 in the air and emit oxygen as a byproduct. It has been thought that these natural
processes of carbon cycling were quite stable
prior to human induce disturbances (Houghton,
2004).
Since the dawn of industrialized times, human activities have caused measurable changes
in the composition of the atmosphere. Anthropogenic carbon compounds emitted to the atmosphere have long been known to have deleterious effects. Since the Industrial Revolution
(circa 1700), the carbon cycle has been imbalanced due to increasing anthropogenic carbon
inputs to the atmosphere. Atmospheric CO2
concentrations have increased approximately
30% from a pre-industrial level of 280 parts per
million (ppm) to present day level of 370 ppm
(Houghton, 2004). As CO2 accumulates in the
atmosphere, the “Greenhouse Effect” is magnified. Compounds in the atmosphere create a
layer above the Earth that let light and heat energy pass through, but do not allow the infrared
radiation (heat) escape as readily.
Terrestrial carbon sequestration can be defined as capture of CO2 and long term storage
out of the atmosphere. Atmospheric carbon can
be removed and pumped into geologic reservoirs,
transported via pipeline to further geologic storage if no local reservoirs are present or sequestered in the biomass of terrestrial vegetation.
Although these seem like viable options to mitigate the ongoing carbon emission problem, each
of these mitigation measures are not without
potential limitations.
STATE OF THE SCIENCE
Recent patterns and mechanisms of carbon
exchange by terrestrial ecosystems
This paper written by Schimel et al. was
published in Nature in 2001 and attempts to
quantify exchange of CO2 between the atmosphere and terrestrial and marine environments in
three different latitudinal zones. This study uses
inverse model calculations to estimate carbon
flux, calculating sources and sinks of carbon
based on CO2 distribution in the atmosphere.
Inverse modeling (the top down approach) is one
of two primary methods of estimating carbon
fluxes between the atmosphere and terrestrial
environments. The primary goals are to identify
the mechanisms controlling atmosphereterrestrial fluxes, analyze spatial patterns of carbon fluxes and develop explanations for interannual variability in flux estimates.
The paper estimates net sinks in terrestrial
and marine environments in the 1980’s and
1990’s. It is suggested that the major mechanisms contributing to the net carbon sink in terrestrial environments is land use change (i.e.
reforestation from former agricultural lands) in
North America and land use, land management
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and increased forest growth due to CO2 fertilization and nitrogen deposition in Europe. The authors suggest that the variability in carbon fluxes
between years is likely due to changes in climatic factors, indicating that there appears to be
a net release of carbon to the atmosphere during
warm and dry years and a net uptake from the
atmosphere during cooler years.
It seems that the authors could have expanded the scope of the paper slightly to include
a comparison of land-based estimation to their
atmosphere-based estimates. This could give
some indication as to the validity of the estimates
if both approaches yielded similar results. These
results address the objectives stated in the paper
quite well. The authors also included a section
of issues needed to be addressed for future research. The carbon cycle is quite a dynamic system, especially when human impacts are added
into the equation. The need for more models
with increasing complexity speaks to the multifaceted nature of the field of global climate
change.
Consistent Land- and Atmosphere-Based
U.S. Carbon Sink Estimates
This paper written by Pacala et al. was published in Science in 2001. The authors attempt
to compare model results of atmosphere-land
carbon fluxes using two different approaches.
The goal of the study was to determine sources
and sinks in the coterminous United States. The
first method is the land-based approach (the bottom up method) in which the authors use data
from direct inventory measurements of carbon,
reconstructions of land use changes and ecosystem models. The second method is the atmosphere-based approach (the top down method) in
which global CO2 concentration data is input into
atmospheric transport models.
The land-based estimates of atmosphere to
ground carbon flux (carbon sink) yielded a much
smaller range of values than did the atmospherebased estimates. However, using seasonal inversion monthly data, the two methods agreed quite
well. These results are quite impressive, when
taking into account the extreme diversity in input
data into the two modeling methods. Both the
land-based and atmosphere-based estimates indicated a large net carbon sink in the United States.
Their analysis also indicated a steady atmosphere
to ground carbon flux for the study period of
1980-1994.
This study is quite well designed in that
both methods used served as a check of sorts to
the other method. When both the land-based and
atmosphere-based estimates of carbon flux are in
general agreement, this serves as verification of
the utility of the each approach.
The Not-So-Big U.S. Carbon Sink
This paper written by Field and Fung was
published in Science in 1999. The primary focus
of the paper is to review two methods of quantifying carbon sinks, the bottom up and the top
down approach. As discussed above, the bottom
up, or land-based approach includes inventory
measurements of carbon and the top down, or
atmosphere-based approach inputs global CO2
data into atmospheric transport models. This
paper is a synthesis of data used in previous
work in order to analyze the two methods of carbon flux estimation and to determine the major
drivers in terrestrial carbon sequestration.
The authors state that changes in historical
land use have emerged as major factors influencing carbon sequestration in addition to factors
such as rising temperatures, increases in atmospheric CO2 and nitrogen deposition. The authors
state that latitudinal estimates are becoming increasingly more reliable for analyzing terrestrial
processes due to a global network of atmospheric
monitoring stations.
The overlying conclusion of the paper
seems to be that changes in historical land use
are quite important when attempting to quantify
terrestrial carbon sources and sinks. They suggest that future research should focus as much on
history of land use practices as on ecosystem
changes and atmospheric composition. However,
it does not seem that the authors put forth a very
exhaustive review of the bottom up and top
down approaches to estimating carbon sinks.
The text is slightly difficult to comprehend and
could use more justification for their conclusions.
The synthesis paper is only based on nine
sources. The paper would be more useful if it
were broken into sections addressing each of the
approaches and then a section for comparison
between the two methods.
PERSPECTIVES IN THE MEDIA AND PUBLIC
POLICY
Carbon sequestration has received much
publicity in the mainstream media as of late. It
becomes big news when a large oil company
such as BP invests money in a technology to
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capture CO2 produced during combustion of coal
at electricity generating plants. BP, for instance,
has entered into an agreement with Powerspan to
develop a cost effective technology to capture
CO2 from power plant emissions (Powerspan,
2007).
Similary, a large scale sequestration project
in Germany, funded by the European Union, is in
the planning stages. The proposed design will
include a facility to inject CO2 into the ground to
a depth of approximately 1880 meters. The initial stages of this project include feasibility testing of the technology and monitoring to determine the long term stability of the stored gas
with a goal of full implementation by 2020
(AgReport, 2007).
CONSIDERATIONS FOR POLICYMAKERS
Although the science behind quantifying
carbon sources, sinks and means of sequestering
atmospheric CO2 are continually improving,
policymakers should not rely on carbon sequestration solely to address the effects of carbon
emissions on global climate change. Although
sequestration projects may help to mitigate effects of increased carbon emissions, the only
method to properly address the problem is to
mandate decreases in emissions of carbon.
There are vast uncertainties concerning the effectiveness of sequestration including but certainly
not limited to: the efficiency of capture and
transport of CO2, long term stability of sequestration projects such as geologic storage, saturation limits of sinks and the unknown response of
terrestrial environments to climate change. Attempts to reduce carbon emissions by means
such as “Carbon Credits” and international treaties like the Kyoto Protocol are steps in the right
direction. The next step will have to include
incentives in order for developing nations to be
able to work to reduce emissions without compromising economic and social well being.
CITED REFERENCES WITH ABSTRACTS
Field, C.B. and Fung, I.Y (1999). The NotSo-Big U.S. Carbon Sink. Science, 285, 544-545.
Atmospheric carbon emitted through human activities is stored in carbon sinks in oceans and
terrestrial ecosystems. Two methods of quantifying the sinks are analyzed.
Houghton, J. (2004). Global Warming: The
Complete Briefing, The greenhouse gases (pp.
28-42). New York, NY: Cambridge University
Press.
Pacala, S.W. et al. (2001). Consistent
Land- and Atmosphere-Based U.S. Carbon Sink
Estimates. Science, 292, 2316-2320.
For the period 1980-89, we estimate a carbon
sink in the coterminous United States between
0.30 and 0.58 petagrams of carbon per year
(petagrams of carbon = 1015 grams of carbon).
The net carbon flux from the atmosphere to the
land was higher, 0.37 to 0.71 petagrams of carbon per year, because a net flux of 0.07 to 0.13
petagrams of carbon per year was exported by
rivers and commerce and returned to the atmosphere elsewhere. These land-based estimates are
larger than those from previous studies (0.08 to
0.35 petagrams of carbon per year) because of
the inclusion of additional processes and revised
estimates of some component fluxes. Although
component estimates are uncertain, about onehalf of the total is outside the forest sector. We
also estimated the sink using atmospheric models
and the atmospheric concentration of carbon
dioxide (the tracer-transport inversion method).
The range of results from the atmosphere-based
inversions contains the land-based estimates.
Atmosphere- and land-based estimates are thus
consistent, within the large ranges of uncertainty
for both methods. Atmosphere-based results for
1980-89 are similar to those for 1985-89 and
1990-94, indicating a relatively stable U.S. sink
throughout the period.
Schimel, D.S. et al. (2001). Recent patterns and mechanisms of carbon exchange by
terrestrial ecosystems. Nature, 414, 169-172.
Knowledge of carbon exchange between the atmosphere, land and the oceans is important,
given that the terrestrial and marine environments are currently absorbing about half of the
carbon dioxide that is emitted by fossil-fuel
combustion. This carbon uptake is therefore limiting the extent of atmospheric and climatic
change, but its long-term nature remains uncertain. Here we provide an overview of the current
state of knowledge of global and regional patterns of carbon exchange by terrestrial ecosystems. Atmospheric carbon dioxide and oxygen
data con®rm that the terrestrial biosphere was
largely neutral with respect to net carbon exchange during the 1980s, but became a net carbon sink in the 1990s. This recent sink can be
largely attributed to northern extratropical areas,
and is roughly split between North America and
Eurasia. Tropical land areas, however, were approximately in balance with respect to carbon
exchange, implying a carbon sink that offset
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emissions due to tropical deforestation. The evolution of the terrestrial carbon sink is largely the
result of changes in land use over time, such as
regrowth on abandoned agricultural land and fire
prevention, in addition to responses to environmental changes, such as longer growing seasons,
and fertilization by carbon dioxide and nitrogen.
Nevertheless, there remain considerable uncertainties as to the magnitude of the sink in different regions and the contribution of different
processes.
Powerspan Corp. “BP and Powerspan Collaborate to Demonstrate and Commercialize CO2
Capture Technology for Power Plants” [Online]
19
November
2007.
<http://www.earthtimes.org/articles/show/news_
press_release,155722.shtml>.
AgReport. “Underground CO2 Storage
Plant in Germany” [Online] 19 November 2007.
<http://www.agreport.com/open/259550.phtml>.
4
The effects of climate change on
coastal regions - with a focus on
the US
Juliette L. Smith
EXECUTIVE SUMMARY
Coastal regions, including shorelines,
estuaries, wetlands, coastal margins, and coral
reefs, are vulnerable to climate change drivers
such as warming oceanic temperatures, sea-level
rise, and precipitation fluctuations. These regions house over ½ of the US population while
providing valuable resources and services such
as aquaculture, freshwater aquifers, and storm
surge protection.
INTRODUCTION
Climate change is predicted to act upon the
world’s coastal regions through three main
forces: an increase in ocean temperature, sealevel rise, and changes in precipitation and river
flow (Scavia et al. 2002, and references therein).
These forces spin a web of direct and indirect
effects on the weather, physical and biogeochemical parameters, ecosystems, culture, and
socioeconomics of coastal regions, including
shorelines, estuaries, coral reefs, coastal wetlands, and ocean margins. Indirect, negative
effects are also predicted for the larger continents
that rely on these fertile regions for numerous
products and services.
Increase in ocean temperature
Warming ocean temperatures are expected
to cause an increase in tropical cyclone strength
and duration (i.e., hurricane, coastal storms), an
increase in coral bleaching, and a northward shift
in coastal region biota. More controversial predictions include an increase in the frequency of
tropical cyclones, the shutdown or speeding up
of ocean circulation, and the switch of estuaries
to act as a nitrogen source instead of sink. The
mean temperature of the upper 300 m of ocean
has increased by 0.31°C over the past 45 yr and
warming has been recorded to depths as low as
3,000 m. The occurrence of widespread, deeper
warmer waters has the potential to increase
tropical cyclone strength and duration as (1)
strength is dependent upon the difference in temperature between the upper, colder troposphere
and the warmer, sea surface temperatures and (2)
storm duration is determined by the geographical
range of warm surface and sub-surface waters
that are necessary to fuel the storm moisture and
postpone negative feedback (i.e., rising cold water beneath the storm’s eye, see Willoughby
1999). Emanuel (2005) showed empirical evidence that tropical cyclone intensity (wind speed
and duration of storm) has significantly increased over the past thirty years, suggesting that
if the predicted rise in sea surface temperature
occurs (1 - 3°C over this century) so will coastal
storm intensity. Socioeconomic hardship is
likely to follow this alarming trend if landfall
occurs, as storm wind speed has been directly
correlated with the cost of a storm. Cyclone frequency, however, is not as predictable, most
likely due to other drivers of cyclones including
vertical and horizontal windsheer and/or internal
dynamics of the storm itself. It is unknown how
climate change will affect windsheer and tropical
storm formation.
Emanuel (2005) suggested that an increase
in cyclone intensity may, in turn, lead to a speeding-up of ocean circulation with more cold,
denser water being brought to the surface at the
equator during a storm making it more easily
sunk when it reaches the poles. This suggestion
is opposite that of the general scientific community which hypothesizes that polar melting and
increased freshwater runoff will increase stratification and hinder vertical mixing, slowing down
the conveyor belt. The Intergovernmental Panel
on Climate Change (IPCC) reports that it is very
likely that there will be a 25% reduction in circulation flow by the end of the century (Scavia et al.
2002). Either way, alteration to ocean circulation is likely to have vast impacts on the location
and intensity of nutrient rich upwelling events,
global climate, and geographic distribution of
coastal biota.
Warmer ocean temperatures are also predicted to increase the frequency and geographic
distribution of coral bleaching events as these
ecosystems already live near their upper thermal
tolerance limits. Warmer temperature periods
have been correlated with zooxanthellae (symbiotic algae) expulsion, slowing or halting of
growth or reproduction, or an increase in pathogen vulnerability. Other anthropogenic effects
such as eutrophication, sedimentation, pollution,
and coastline development will most likely hinder the ecosystems ability to migrate or recolonize at the same location. Similarly, estuarine,
wetland and shoreline biota will most likely have
to migrate northwards or adapt when thermal
tolerances are exceeded.
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In the last two years, scientists have recorded an alarming shift in US estuaries as these
bodies of water have suddenly become a source,
instead of sink, for nitrogen (Lane 2007). Scientists argue that the switch is due to a community
shift towards nitrogen-fixing bacteria or cyanobacteria as a result of oceanic warming; however,
the empirical data are sparce and rely on a comparison of only four years: 1979, 1986, 2005,
and 2006 (Fulweiler et al. 2007). If true, however, this net influx of nitrogen into the system
may put the coastal ocean at risk for acidification
(i.e., nitrate is acidic) or the occurrence of harmful algal blooms and fish/shellfish kills as ammonia or nitrate levels rise. More research is
needed to confirm this trend and determine the
mechanism(s) behind the shift.
Sea-level rise
Sea-level rise has been a continuous threat
to wetlands, shorelines, and human development
over the last 100 years, rising at an average of 10
– 20 cm. This threat has been bearable with adaptation, migration, or constructive barriers.
Over the next 100 years, however, sea level is
predicted to rise another 9 – 88 cm according to
the IPCC (Scavia et al. 2002). The final level
will be determined by the actual amount and
duration of greenhouse gas emissions, rise in
atmospheric and oceanic temperatures, and the
amount of glacial and ice cap melt.
Coastal regions are very sensitive to a rise
in sea level (Scavia et al. 2002, and references
therein). A rapid or substantial rise will likely
prevent wetlands from accumulating peat or
sediment, and therefore, cause wetland submersion or erosion. If migration inland is obstructed,
then wetlands and shoreline will be lost. Human
development is also subjected to this threat, as
over ½ of the US population already lives on the
17% of land considered coastal and another 18
million Americans are predicted to move to the
coast (i.e., CA, FL, TX, and WA). Shoreline
flooding, the inundation of freshwater aquifers,
and the subsequent motility of toxic chemicals
and water-borne pathogens are predicted to have
large monetary implications, with a 50-cm sealevel rise estimated to cost between $20 and
$200 billion by the end of this century. Protection from storm surges will also decrease as wetlands are lost to inundation.
Changes in precipitation and river flow
Although prediction models contradict in
regards to whether the US will experience more
or less precipitation with climate change, they
converge to state that there will be more extreme
rainfall events, floods, and droughts (Scavia et al.
2002, and references therein). Precipitation runoff supplies the coastal embayments with freshwater, nutrients, and sediment. Without the delivery of sediment, the erosion of shoreline and
loss of wetlands are to be expected; however, a
sudden influx of sediments, nutrients, or freshwater (e.g., flooding or high rainfall event) can
cause a wetland to be buried and the physical and
biogeochemical status of the receiving water
body to be altered. Alterations to freshwater
input can also affect localized salinity levels in
the estuaries and wetlands, thereby indirectly
controlling the biotic community. For example,
a period of decreased runoff or drought would
likely result in an increase in salinity, conditions
under which mangroves, a diverse nursery for
fish, mammals and invertebrates, would perish.
STATE OF THE SCIENCE
Emanuel (2005):
In this modeling paper the author plots
smoothed mean sea-surface temperatures (SST)
of the Atlantic in September, the western North
Pacific from July – November, and the Atlantic
+ western North Pacific, as an annual mean,
against storm intensity from 1950 – 2005. In all
three cases, a significant positive relationship is
derived, giving evidence for an increasing trend
in cyclone intensity over the last 30 years. Storm
intensity is described as an index of power dissipation (PDI), a measure based mostly on the
wind speed and duration of the storms that occurred.
Willoughby (1999):
This work provides an explanation on how
tropical cyclones are formed and sustained.
Tropical cyclones are created through the collision and organization of already occurring thunderstorms that converged around a low-surface
pressure zone. Overall, the storm relies upon the
transfer of energy between the ocean surface and
the upper troposphere. As warm surface air
passes over the warm ocean, evaporation occurs.
As the warm moist air mass rises in altitude the
surrounding cooler temperatures and increased
pressure of the troposphere causes condensation
and cloud formation. Condensation releases heat
which is mostly dissipated through precipitation.
The cooled, dry air mass moves outward due to
the coriolis effect and high pressure center at the
top of the storm, and consequently, sinks. As the
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air mass sinks it warms as a result of compression due the surrounding atmosphere, and is
again moved across the sea surface towards the
low pressure eye while accumulating water vapor. As the storm continues, more energy transferred, resulting in greater winds, and more
evaporation - the high and low pressure centers
strengthen and even more energy is brought into
the system.
Climate change affects tropical cyclones because the ocean’s surface is warming at
a greater rate than the upper troposphere making
the temperature difference greater. The storm
intensifies because a greater differential equates
to a greater power exchange between the water
surface and upper troposphere through evaporation/condensation. Additionally, the warming of
the subsurface waters (3,000m) allows a storm to
last longer as it then takes longer for colder
warmers to upwell under the storm’s eye and
cause a negative feedback.
Fulweiler et al. (2007):
In this research paper, sediment samples
collected from Narragansett Bay, RI in 2006
switched to being a net source of nitrogen instead of a net sink. Four studies, consisting of
different years, were compiled, showing a sudden increase in nitrogen fixation in 2006 as compared to 1979, 1986 and 2005 which instead
were years with high rates of denitrification. The
second point of the article was that phytoplankton biomass has decreased as a result of global
warming. The data presented to support this
theory was a scatter plot of years against mean
summer chlorophyll a concentrations. A trend of
decreasing chlorophyll a concentrations over
time occurred; however, sea surface or atmospheric temperatures were not plotted on the figure. I felt this work was representative of a preliminary study instead of a conclusive work and
should be followed up with future annual measurements. In addition, I think future studies
should include more spatial distribution across
the estuary as different regions of the water body
are acting differently and sediments are inherently patchy.
Scavia et al. (2002):
Scavia et al. (2002) provides a comprehensive review of predicted climate change impacts on US coastal and marine ecosystems and
possible adaptation and coping strategies. Major
forces of climate change identified by the authors
include changes to sea-level, coastal storms,
freshwater inflow, ocean temperature and ice
extent, and ocean circulation. Impacts are predicted against the weather, organisms, ecosystems, culture, socioeconomics, and health of
coastal regions.
PERSPECTIVES IN THE MEDIA AND PUBLIC
POLICY
Lane (2007):
Disappointingly, this news feature in
Nature did not provide a satisfactory synthesis of
studies, and instead barraged the reader with
numerous speculations and hypotheses in a manner that was hard to follow or evaluate. The
main points of the article were that (1) estuaries
are switching from being a nitrogen sink to now
a nitrogen source and (2) that the switch is recent
and a result of global warming. No direct evidence was provided and the reader was forced to
read the original articles to gain an understanding
of the arguments (see Fulweiler et al. 2007). And
worse, the reader is left feeling skeptical of
global warming and the science behind its possible impacts.
Kerr (2007):
Interestingly, this news focus article in Science began with an image of five devastated
Louisianans wading their way down a flooded
street with a caption that read “ungentle reminder.
Katrina's destruction brought global warming to
mind.” Kerr points out that the public’s awareness of global warming is largely linked to “climate science and weird weather:” Ice-melting of
the Arctic, daffodil blooms in Washington, D.C
in January, and most recently, the raging hurricane, Katrina. It was this last association that
drew my attention; Katrina being used as a
poster child for global warming. Although I see
the value in this association, I feel it may be a bit
premature as the science is not sufficient to support the claim. As discussed earlier, a positive,
significant relationship exists between warming
sea surface temperatures (SST) and tropical cyclone wind speed and duration (Emanuel 2005);
however, not enough data yet exists to determine
if there is also a relationship between SST and
the frequency of cyclone development or the
landfall of storms. Based on current data,
Katrina was an example of poor land management, but its direct connection to global warming
is still to be confirmed.
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CONSIDERATIONS FOR POLICYMAKERS
I am unaware of any US policy specifically
in place to protect coastal regions from possible
future impacts associated with climate change,
such as dramatic sea-level rise, warming ocean
temperatures, or changes in precipitation or river
runoff. Instead, policies exist to protect coastal
regions from threats that have already been identified by governments. Such policies focus on
pollution and nutrient abatement, marine ecosystem preserves, fishery closures, and wetland protection and mitigation. Additionally, local government has taken action to protect personal
property against beach/shoreline erosion, coastal
flooding, and storm surges; however, I believe
these regulations do not take into account the
expected rise in sea level, local predictions for
precipitation change, or increased ocean temperatures over the next few decades. Before new
policy can be made, global warming impacts
must be (1) further studied, independent, from
other environmental threats (e.g., eutrophication,
sedimentation, pollution, shoreline development,
hydrology alteration, etc.) and (2) studied in conjunction with these threats to look for compensatory, additive, or synergistic effects.
CITED REFERENCES WITH ABSTRACTS
Emanuel, K. 2005 Increasing destructiveness of tropical cyclones over the past 30 years.
Nature 436; 686-688.
Theory and modeling predict that hurricane intensity should increase with increasing global
mean temperatures, but work on the detection of
trends in hurricane activity has focused mostly
on their frequency and shows no trend. Here I
define an index of the potential destructiveness
of hurricanes based on the total dissipation of
power, integrated over the lifetime of the cyclone,
and show that this index has increased markedly
since the mid-1970s. This trend is due to both
longer storm lifetimes and greater storm intensities. I find that the record of net hurricane power
dissipation is highly correlated with tropical sea
surface temperature, reflecting well-documented
climate signals, including multi-decadal oscillations in the North Atlantic and North Pacific, and
global warming. My results suggest that future
warming may lead to an upward trend in tropical
cyclone destructive potential, and—taking into
account an increasing coastal population—a substantial increase in hurricane-related losses in the
twenty-first century.
Fulweiler, R.W., Nixon, S.W., Buckley,
B.A., Granger, S.L. 2007 Reversal of the net
dinitrogen gas flux in coastal marine sediments.
Nature 448; 180-182.
The flux of nitrogen from land and atmosphere
to estuaries and the coastal ocean has increased
substantially in recent decades. The observed
increase in nitrogen loading is caused by population growth, urbanization, expanding water and
sewer infrastructure, fossil fuel combustion and
synthetic fertilizer consumption. Most of the
nitrogen is removed by denitrification in the
sediments of estuaries and the continental shelf,
leading to a reduction in both cultural eutrophication and nitrogen pollution of the open ocean
Nitrogen fixation, however, is thought to be a
negligible process in sub-tidal heterotrophic marine systems. Here we report sediment core data
from Narragansett Bay, USA, which demonstrate
that heterotrophic marine sediments can switch
from being a net sink to being a net source of
nitrogen. Mesocosm and core incubation experiments, together with a historic data set of
mean annual chlorophyll production support the
idea that a climate-induced decrease in primary
production has led to a decrease in organic matter deposition to the benthos and the observed
reversal of the net sediment nitrogen flux. Our
results suggest that some estuaries may no longer
remove nitrogen from the water column. Instead,
nitrogen could be exported to the continental
shelf and the open ocean and could shift the effect of anthropogenic nitrogen loading beyond
the immediate coastal zone.
Kerr, R.A. 2007 U.S. Policy: A Permanent
Sea Change? Science 315 (5813); 756 – 757.
Lane, N. 2007 Climate change: What's in
the rising tide? Nature 449; 778-780.
Scavia, D., Field, J.C., Boesch, F., Buddemeier, R.W., Burkett, V., Cayan, D., Fogarty, M.,
Harwells, M.A., Howarth, R.W., Mason, C.,
Reed, D.J., Royer, T.C. Sallenger, A.H., Titus,
J.G. 2002 Climate Change Impacts on U.S.
Coastal and Marine Ecosystems. Estuaries 25 (2);
149–164.
Increases in concentrations of greenhouse gases
projected for the 21st century are expected to
lead to increased mean global air and ocean temperatures. The National Assessment of Potential
Consequences of Climate Variability and
Change (NAST 2001) was based on a series of
regional and sector assessments. This paper is a
summary of the coastal and marine resources
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sector review of potential impacts on shorelines,
estuaries, coastal wetlands, coral reefs, and ocean
margin ecosystems. The assessment considered
the impacts of several key drivers of climate
change: sea level change; alterations in precipitation patterns and subsequent delivery of freshwater, nutrients, and sediment; increased ocean
temperature; alterations in circulation patterns;
changes in frequency and intensity of coastal
storms; and increased levels of atmospheric CO2.
Increasing rates of sea-level rise and intensity
and frequency of coastal storms and hurricanes
over the next decades will increase threats to
shorelines, wetlands, and coastal development.
Estuarine productivity will change in response to
alteration in the timing and amount of freshwater,
nutrients, and sediment delivery. Higher water
temperatures and changes in freshwater delivery
will alter estuarine stratification, residence time,
and eutrophication. Increased ocean temperatures
are expected to increase coral bleaching and
higher CO2 levels may reduce coral calcification,
making it more difficult for corals to recover
from other disturbances, and inhibiting poleward
shifts. Ocean warming is expected to cause
poleward shifts in the ranges of many other organisms, including commercial species, and
these shifts may have secondary effects on their
predators and prey. Although these potential
impacts of climate change and variability will
vary from system to system, it is important to
recognize that they will be superimposed upon,
and in many cases intensify, other ecosystem
stresses (pollution, harvesting, habitat destruction, invasive species, land and resource use,
extreme natural events), which may lead to more
significant consequences.
Willoughby, H.E. 1999 Hurricane heat engines. Nature 401; 649-650.
5
Climate Change Effects on
Biodiversity and Species Ranges
Lisa Giencke
EXECUTIVE SUMMARY
Climate envelope modeling is one of the
key methods that scientists have been utilizing in
order to predict how future climate change will
affect species ranges. However, there has been
some dispute within the scientific community as
to the accuracy and usefulness of these models.
The main criticisms are that these models do not
account for biotic interactions, genetic adaptation
or dispersal. As our knowledge about these
subjects improves, it will be increasingly
important to include them into species range
models. For now, however, these bioclimate
models, if environmental variables are used in
the appropriate context and if the inherent
limitations of these models are presented in full,
are a means to investigate the magnitude of
range changes.
Many studies have been conducted
throughout the world showing the changes that
have already occurred due to a moderately small
change (compared at least to what is possible in
the future) in global climate. One study shows
that on average, across a variety of taxonomic
groups, range changes are approximately 6.1 km
or m poleward or upward in elevation per decade
(Parmesan and Yohe 2003). Other studies take a
broader look at some of the ecological responses
that can be attributed to climate change. Still
other studies look at extinction rates and predict
that somewhere between 15-37% of species will
be “committed to extinction” by 2050, if the
mid-range prediction in climate change and
emission standards are accurate (Thomas et al
2004).
INTRODUCTION
According to the Synthesis Report of
the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change
there has been an increase in global surface
temperature of 0.74º C in the last 100 years. The
report goes on to say, “In terrestrial ecosystems,
earlier timing of spring events and poleward and
upward shifts in plant and animal ranges are with
very high confidence linked to recent warming”
(IPCC 2007). Therefore, it is becoming
increasingly important that we investigate the
consequences of further climate change that will
be manifested in species distributions and
biodiversity.
STATE OF THE SCIENCE
In order to understand how scientists make
predictions about the future range of a given
species, we should first examine the models
behind the science. One of the key ways of
predicting such changes is through the use of
bioclimate envelope models. The article by
Pearson and Dawson (2003) provides an
informative overview, and it also provides some
of the main criticisms (and counter-criticisms) in
the design of these models.
Two of the main approaches of bioclimate
envelope models are to either correlate current
species distributions with environmental
conditions or to examine physiological responses
of a given species to its environment. In either
case, it is assumed that species will show the
same response to the environment in the future
as they do today, and so climate change
scenarios are used to simulate future distribution.
There are three major criticisms often
directed toward the bioclimate envelope
approach, which are: it does not accurately take
into account biotic interactions, evolution or
genetic adaptation or dispersal ability. In each
case, the authors provide either a countercriticism or show how models could be
improved in the future with a better
understanding of the complexity of each issue.
In answering the question posed by the
article (are bioclimate envelopes useful?), it is
clear that the authors would agree that they are.
They conclude the article by providing a
hierarchical framework within which future
models should be designed. They assert that this
framework is not perfect and may be over
simplistic, but that it at least provides some
guidelines as to what environmental variables
should be considered when modeling at various
scales. As with any predictions of the future,
there are inherent limitations to the accurate
simulation of species ranges into the future.
These are due in large part to our as-yet
imperfect understanding of the complexity of
natural systems. The authors conclude that
bioclimate envelopes models are a good first
pass toward understanding the magnitude of the
changes to be expected. Even so, they stress the
importance knowing the limitations of these
models
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Many studies have been conducted
using bioclimate envelope models and other
methods to determine if there is already a
detectable influence of climate change on species
ranges, biodiversity and extinction. One of these
concluded, as they termed it, that a “globally
coherent climate fingerprint” does indeed exist
(Parmesan & Yohe 2003). Their research used a
probabilistic model to determine how likely it is
that climate is the major force behind observed
range and phenological changes. The results
show that 74-91% of documented changes occur
in the direction expected based on climate
change predictions and that these changes
amount to a shift of 6.1 km toward the poles or
m upward in elevation.
Another study (Walther et al. 2002)
reviewed the various ecological changes that are
being in observed in various ecosystems,
spanning from species- to community-level
effects. The paper focuses on changes in
phenology, species ranges, invasive species,
community composition and biotic interactions.
Changes have been observed in the spring timing
of many biological activities including flowering,
bird migration and calling or singing in
amphibians and birds. Species ranges, as noted
above, are moving poleward or upward in
accordance with climate changes. Species
invasions are expected to increase as non-native
organisms are more likely to survive in regions
that were previously inhospitable. Community
composition is expected to change since climate
change will cause individual species to react in
different ways. This has the potential to change
dynamics between trophic levels. Despite
lingering uncertainties, it is clear that climate is
playing a role in each of the above cases.
Other studies have focused on the risk
of species extinctions. One study used a
bioclimate envelope approach, and specifically
took into account dispersal ability by using two
dispersal scenarios: one of no dispersal and one
of high (universal) dispersal. The authors claim
that species will likely fall somewhere inbetween these scenarios – that is, these two
scenarios form the upper and lower bounds of
likely extinction values. Looking only at
endemic species of various taxonomic groups
across the world, the study predicts that 15-37%
of species will be “committed to extinction” by
2050, given a mid-range climate change scenario
(Thomas et al. 2004). A more recent study found
that “For ectothermic animals with relatively
short generation times, at least, climate change
already appears to have joined habitat loss,
invasive species and overexploitation as a major
driving force of population- and species-level
extinctions” (Thomas et al. 2006).
PERSPECTIVES IN THE MEDIA AND PUBLIC
POLICY
As part of a year-long effort in
conjunction with National Geographic, National
Public Radio is producing a special series called
“Climate Connections” with the objective to
examine “how climate changes people and how
people change climate.” One recent installment
(October 29, 2007) examined the effect that
climate is having on sugar maples in New
England. The sugar maple is crucial for its
production of syrup and is very sensitive to
changes in climate. Many maple syrup producers
are having a hard time extracting the same
quantity of sap from the trees that they have
gotten in the past.
As the example above shows, the
species that are going to garner the most
attention as climate change continues to unfold
are the relatively few charismatic plant and
animal species that people know and pay
attention to. Changes in butterfly, wildflower and
bird distributions or abundance will surely be
noticed before all the millions of more mundane
creatures, including insects, invertebrates and
bacteria, whose contribution to ecosystems may
not yet be fully realized, and that may not ever
be known to science before they become extinct.
Even species of great scientific importance, such
as two species of gastric brooding frog that
possessed a previously unknown method of
reproduction, are at risk – both frogs have ceased
to be seen in the wild, one just months after it
was first discovered (Flannery 2005).
CONSIDERATIONS FOR POLICYMAKERS
Besides knowing how climate change is
going to effect species ranges and extinction
rates, it will be ever more important for
policymakers to consider the importance of the
interplay between climate change and habitat
fragmentation. Even species with high dispersal
abilities may have a hard time migrating through
the human-modified environment. One solution
to this problem might be the creation and
implementation of conservation corridors which
would hopefully allow at least some species to
migrate unimpeded by development.
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Changes in ranges and extinctions of
charismatic organisms may spark some policy
initiatives limiting greenhouses gases, as the
policymakers and general public start to observe
for themselves the consequences of climate
change.
LITERATURE CITED
In New England, Concern Grows for Sugar
Maple (Climate Connections). Ketzel Levine.
NPR, Washington, D.C. 29 Oct. 2007.
Summary for Policymakers of the Synthesis
Report of the IPCC Fourth Assessment Report.
Intergovernmental Panel on Climate Change.
2007.
Flannery, Tim. The Weather Makers. Text
Publishing Company: Melbourne, Australia.
2005.
Parmesan, C. & Yohe, G. A globally
coherent fingerprint of climate change impacts
across natural systems. Nature 421, 37–42
(2003).
Pearson, R. G. & Dawson, T. P. Predicting
the impacts of climate change on the distribution
of species: are bioclimate envelope models
useful? Global Ecol. Biogeog. 12, 361–371
(2003).
Thomas, C. D. et al., Extinction risk from
climate change. Nature 427, 145 (2004).
Thomas, C.D., Franco, A.M.A. & Hill J.K.
Range retractions and extinction in the face of
climate warming. Trends Ecol.. Evol 21, 415-416
(2006).
Walther, G.R., Post, E., Convey, P., Menze,
1, A., Parmesan, C., Beebee, T.J.C., Fromentin,
J.M.,
Hoegh-Guldberg,
O.&Bairlein,
F.
Ecological responses to recent climate change.
Nature 416, 389–395 (2002).
ABSTRACTS FROM CITED REFERENCES
1. Predicting the impacts of climate change
on the distribution of species: are bioclimate
envelope models useful?
2. A globally coherent fingerprint of
climate change impacts across natural systems.
3. Ecological responses to recent climate
change.
4. Extinction risk from climate change.
Pearson, R. G. & Dawson, T. P. Predicting
the impacts of climate change on the distribution
of species: are bioclimate envelope models
useful? Global Ecol. Biogeog. 12, 361–371
(2003).
Modelling strategies for predicting the
potential impacts of climate change on the
natural distribution of species have often focused
on the characterization of a species' bioclimate
envelope. A number of recent critiques have
questioned the validity of this approach by
pointing to the many factors other than climate
that play an important part in determining
species distributions and the dynamics of
distribution changes. Such factors include biotic
interactions, evolutionary change and dispersal
ability. This paper reviews and evaluates
criticisms of bioclimate envelope models and
discusses the implications of these criticisms for
the different modelling strategies employed. It is
proposed that, although the complexity of the
natural system presents fundamental limits to
predictive modelling, the bioclimate envelope
approach can provide a useful first
approximation as to the potentially dramatic
impact of climate change on biodiversity.
However, it is stressed that the spatial scale at
which these models are applied is of fundamental
importance, and that model results should not be
interpreted without due consideration of the
limitations involved. A hierarchical modelling
framework is proposed through which some of
these limitations can be addressed within a
broader, scale-dependent context.
Parmesan, C. & Yohe, G. A globally
coherent fingerprint of climate change impacts
across natural systems. Nature 421, 37–42
(2003).
Causal attribution of recent biological
trends to climate change is complicated because
non-climatic influences dominate local, shortterm biological changes. Any underlying signal
from climate change is likely to be revealed by
analyses that seek systematic trends across
diverse species and geographic regions; however,
debates within the Intergovernmental Panel on
Climate Change (IPCC) reveal several
definitions of a 'systematic trend'. Here, we
explore these differences, apply diverse analyses
to more than 1,700 species, and show that recent
biological trends match climate change
predictions. Global meta-analyses documented
significant range shifts averaging 6.1 km per
decade towards the poles (or metres per decade
3
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upward), and significant mean advancement of
spring events by 2.3 days per decade. We define
a diagnostic fingerprint of temporal and spatial
'sign-switching' responses uniquely predicted by
twentieth century climate trends. Among
appropriate long-term/large-scale/multi-species
data sets, this diagnostic fingerprint was found
for 279 species. This suite of analyses generates
'very high confidence' (as laid down by the IPCC)
that climate change is already affecting living
systems.
Walther, G.R., Post, E., Convey, P., Menze,
1, A., Parmesan, C., Beebee, T.J.C., Fromentin,
J.M.,
Hoegh-Guldberg,
O.&Bairlein,
F.
Ecological responses to recent climate change.
Nature 416, 389–395 (2002).
There is now ample evidence of the
ecological impacts of recent climate change,
from polar terrestrial to tropical marine
environments. The responses of both flora and
fauna span an array of ecosystems and
organizational hierarchies, from the species to
the community levels. Despite continued
uncertainty as to community and ecosystem
trajectories under global change, our review
exposes a coherent pattern of ecological change
across systems. Although we are only at an early
stage in the projected trends of global warming,
ecological responses to recent climate change are
already clearly visible.
greenhouse gas emissions and strategies for
carbon sequestration.
Thomas, C.D., Franco, A.M.A. & Hill J.K.
Range retractions and extinction in the face of
climate warming. Trends Ecol.. Evol 21, 415-416
(2006).
Until recently, published evidence for the
responses of species to climate change had
revealed more examples of species expanding
than retracting their distributions. However,
recent papers on butterflies and frogs now show
that
population-level
and
species-level
extinctions are occurring. The relative lack of
previous information about range retractions and
extinctions appears to stem, at least partly, from
a failure to survey the distributions of species at
sufficiently fine resolution to detect declines, and
from a failure to attribute such declines to
climate change. The new evidence suggests that
climate-driven extinctions and range retractions
are already widespread.
C. D. Thomas et al., Extinction risk from
Climate Change. Nature 427, 145 (2004).
Climate change over the past ~30 years has
produced numerous shifts in the distributions and
abundances of species1,2 and has been
implicated in one species-level extinction3.
Using projections of species’ distributions for
future climate scenarios, we assess extinction
risks for sample regions that cover some 20% of
the Earth’s terrestrial surface. Exploring three
approaches in which the estimated probability of
extinction shows a powerlaw relationship with
geographical range size, we predict, on the basis
of mid-range climate-warming scenarios for
2050, that 15–37% of species in our sample of
regions and taxa will be ‘committed to
extinction’. When the average of the three
methods and two dispersal scenarios is taken,
minimal climate-warming scenarios produce
lower projections of species committed to
extinction (~18%) than mid-range (~24%) and
maximum change (~35%) scenarios. These
estimates show the importance of rapid
implementation of technologies to decrease
4
The Effect of Climate Change on
Species’ Phenology
Laura Heath
EXECUTIVE SUMMARY
Phenology is the timing of development
from one point in an organism’s life cycle to
another. Phenological events can include timing
of flowering, leaf out, migration, and
reproduction, amongst others.
Due to the
dependence of many phenological events on
temperature, species’ phenology is thought to be
one of the easiest ways to document the
occurrence of global climate change. In addition,
changes in species’ phenologies have the
potential to impact ecological processes,
agriculture, forestry, economics and human
health.
Current scientific research indicates that
many geographic areas within the mid-latitudes
of the northern hemisphere have shown increases
in the onset of spring and delays in the onset of
fall. Research has determined that globally, and
across multiple trophic levels, phenologies are
occurring an average of 2.3 days earlier per
decade (Parmesan and Yohe 2003). Research
has documented earlier onset of tree bud burst
(Badeck et al. 2004), plant flowering (Fitter and
Fitter 2002), frog calling (Gibbs and Breisch
2001), bird migration (Cotton 2003) and bird
egg-laying (Dunn and Winkler 1999). Although
changes in species’ phenologies are not always
detrimental to ecosystem functioning, they can
be in situations where one organism is highly
dependent on the timing of a life cycle event of
another organism. One such example is the
recent observation that cold winters and warm
springs are causing unequal rates of
advancement of winter moth (Operophtera
brumata) egg hatching and English oak (Quercus
robur) bud burst, causing moths to hatch before
their food source (oak) has developed (Visser
and Holleman 2001).
Change in species’ phenologies is a
subject easily understood by the public and
therefore used in the mass media as a way to
demonstrate the validity of global warming.
Although earlier onset of spring and later onset
of fall could be perceived as positive
consequences of global climate change, the
media still recognizes these changes as abnormal,
which is essential in conveying the serious
nature of global climate change. It is therefore
necessary that policymakers use phenology data
as strong evidence that global warming is a
serious threat and impetus to take action.
INTRODUCTION
Phenology is defined in biology as the
timing of life history events. Such events
include breeding, migration, hibernation,
metamorphosis, leaf out, bud burst, flowering
and leaf senescence, amongst others. It has been
well documented that many life history events
vary from year to year based on climate
conditions, and as a result, it is thought that
phenology will be one of the earliest and most
easily recognizable traits that change in response
to global climate change. In addition, phenology
is a subject easily identifiable with the general
public, as the public’s connection to the natural
world is often associated with elements such as
flowering time, bird migration and leaves
changing color.
Changes in plant phenology have the
potential to have many ecological, social and
economic impacts. Agricultural and forestry
industries can be affected by changes in plant
productivity, length of growing season and
zoning that can ultimately result from changes in
plant phenology. Changes in phenology can also
alter ecological systems by altering interspecific
competition,
disrupting
highly
coupled
associations amongst organisms at different
trophic levels and altering the terrestrial carbon
balance. Finally, changes in plant phenology can
impact human health, such as changes in the
timing and abundance of pollen release, which
affects the seriousness and treatment of allergies.
This paper will explore the current knowledge on
the impacts of global climate change on species’
phenologies.
STATE OF THE SCIENCE
Long-term phenological data has
historically been collected by amateur naturalists
with a connection to the agricultural industry.
Today, many countries of Europe, North
America and Asia have developed national
phonological networks to aid in long-term data
collection and compilation. The phenology
network of the United States began in 2007 and
aims to get citizens involved in phenology data
collection (such as bud burst, flowering time and
first site of migratory birds) in order to build a
dataset that is as large as possible and
geographically extensive.
The phenological
network of Britain currently has 50,000 citizens
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submitting phenology data every year.
In
addition to “on the ground” data collected by
citizens and scientists around the world, new
technology has recently allowed for large-scale
data collection using satellite technology. The
Normalized Difference Vegetation Index (NDVI)
is a remote-sensing technique using NASA
satellites that measure the amount of light
reflecting off the earth at varying wavelengths.
This technology is based on the principle that
green plants absorb visible light (at wavelengths
0.4-0.7 µm) and reflect near infrared light (at
wavelengths 0.7-1.1µm).
As a result,
measurements of visible and infrared light
reflectance by the earth can serve as a way to
quantify how green the earth is over time, and
therefore how the onset of spring and fall is
changing.
breeders, exhibited earlier first calling dates, up
to 13 days earlier, in the 1990’s as compared to
the period from 1900 to 1912. In addition,
average daily temperatures increased over the
last century during 5 of the 8 months important
for frog development, indicating that earlier first
calling dates could be a biotic response to
increased temperatures. Changes in time of
reproduction have also been documented for tree
swallows in North America. Dunn and Winkler
(1999) found that tree swallows exhibited
advancement in egg-laying by an average of 9
days from 1959 to 1991. In addition, egg-laying
date was highly correlated to mean May air
temperatures. Finally, Cotton (2004) found that
birds in England migrate from sub-Saharan
Africa an average of 8 days earlier than they did
30 years ago.
Many studies encompassing large
geographical areas and habitat types now report
that plant and animal species’ phenologies are
changing as of late, which have been shown to
be correlated to increasing temperatures. Fitter
and Fitter (2002) presented data, collected by a
single observer, concerning the first flowering
dates of 385 plant species in Britain from 1954
to 2000. The authors determined that the plants
flowered an average of 4.5 days earlier in the
1990’s than the previous decades.
First
flowering date of plants blooming in February,
March and April were correlated with
temperatures of the previous month (January,
February and March, respectively). In addition,
annual plants exhibited earlier average flowering
date in the 1990’s by 7.8 days than perennials,
with an average of 3.2 days earlier. Finally,
insect-pollinated plants had an earlier first
flowering date (by 4.8 days) than windpollinated plants (3.5 days earlier) and insectpollinated plants flowering in the spring
appeared to be most sensitive to warming. The
fact that spring-flowering, insect-pollinated
plants flowered earlier in the 1990’s than all
other plant types could have drastic
consequences on those insect-plant systems,
especially if synchrony of insect development
and plant flowering is lost. The work discussed
in this paper is particularly important not only
because it has a long timeframe (1954-2000), but
also because it is the only phenology study that
uses data collected by a single observer.
Although
changes
in
species’
phenologies due to global climate change will
not always be detrimental to organisms, some
highly specialized systems are threatened by
global warming. One such system is that of the
winter moth (Operophtera brumata) and English
oak (Quercus robur). Winter moth egg hatching
is timed to coincide with oak bud burst such that
moth larvae can feed on young, easily digestible
oak leaves. Visser and Holleman (2001), using
descriptive modeling techniques, found that
between 1975 and 2000, there has been an
increase in the mis-timing of moth egg hatching
and oak bud burst. The authors attributed this
result to recent increases in spring temperatures,
which cause advancement of both moth egg
hatching and oak bud burst, but no subsequent
changes in the number of winter frost days,
which delays oak development. Therefore,
warm springs and cold winters lead to egg
hatching up to three weeks before bud burst,
which can result in large-scale mortality of
moths. This example of loss of synchrony across
trophic levels is particularly important because it
demonstrates that organisms highly dependent
on one another can become threatened by global
climate change.
Phenologies of animals have also been
shown to be affected by global warming. Gibbs
and Breisch (2001) found that many frogs of
central New York, especially early spring
PERSPECTIVES IN THE MEDIA AND PUBLIC
POLICY
Change in species’ phenologies over time is
a subject that is easily understood by the general
public.
Many media outlets, including
magazines and local newspapers, have used
phenological data to demonstrate the validity of
global warming. An article published in the
New York Times entitled “March may be
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coming in like a lamb” summarizes, in a simple
but accurate way, current knowledge on
phenological changes that have been attributed to
global warming (Stevens 1999). Although this
article could easily spin the concept of earlier
spring onset as a positive consequence of global
climate change, it recognizes that these observed
changes are not consistent with historical trends.
As a result, changes in phenology hold the
potential to be a poster child for the public to
demonstrate that global warming is indeed
occurring, as demonstrated by the assertion in
the article that “all the recent studies indicate that
a warming and greening of the planet is indeed
under way” (Stevens 1999). However, some
media outlets, especially those without a strong
base in science, generally focus on consequences
of phenology changes that have a direct impact
on peoples’ daily lives rather than broad
ecological functioning. Such topics include the
effects of climate change on gardening, winter
and spring recreation, and the maple syrup
industry. Although the human aspect of the
problem is important, it gives an incomplete
perspective on the issue.
CONSIDERATIONS FOR POLICYMAKERS
The effects of climate change on
species’ phenology have been strongly
documented. However, in only a few cases has
research shown that these changes cause a
breakdown of ecological systems. Therefore, it
is unlikely, with the current level of scientific
knowledge on changes in phenology, that
government officials will institute policy aimed
at maintaining species’ phenology in the wake of
climate change.
Although
changes
in
species’
phenology are some of the strongest and most
accessible evidence for global climate change,
there are inherent drawbacks to the data. Trends
in this field rely primarily on correlations
between changes in phenology and changes in
temperature. However, causation cannot be
inferred from correlations. As a result, one
cannot state without a doubt that recent increases
in spring temperature are causing the observed
changes in species’ phenology, although the
probability of causation is high.
REFERENCES
Badeck, F.W, A. Bandeau, K. Bottcher, D.
Doktor, W. Lucht, J. Schaber and S. Sitch. 2004.
Responses of spring phenology to climate
change. New Phytologist 162: 295-309.
Climate change effects on seasonal activity in
terrestrial ecosystems are significant and well
documented, especially in the middle and higher
latitudes. Temperature is a main driver of many
plant developmental processes, and in many
cases higher temperatures have been shown to
speed up plant development and lead to earlier
switching to the next ontogenetic stage.
Qualitatively consistent advancement of
vegetation activity in spring has been
documented using three independent methods,
based on ground observations, remote sensing,
and analysis of the atmospheric CO2 signal.
However, estimates of the trends for
advancement obtained using the same method
differ substantially. We propose that a high
fraction of this uncertainty is related to the time
frame analysed and changes in trends at decadal
time scales. Furthermore, the correlation between
estimates of the initiation of spring activity
derived from ground observations and remote
sensing at interannual time scales is often weak.
We propose that this is caused by qualitative
differences in the traits observed using the two
methods, as well as the mixture of different
ecosystems and species within the satellite
scenes.
Cotton, P.A. 2003. Avian migration
phenology and global climate change.
Proceedings of the National Academy of
Sciences 100: 12219-12222.
There is mounting evidence that global climate
change has extended growing seasons, changed
distribution patterns, and altered the phenology
of flowering, breeding, and migration. For
migratory birds, the timing of arrival on breeding
territories and over-wintering grounds is a key
determinant
of
reproductive
success,
survivorship, and fitness. But we know little of
the factors controlling earlier passage in longdistance migrants. Over the past 30 years in
Oxfordshire, U.K., the average arrival and
departure dates of 20 migrant bird species have
both advanced by 8 days; consequently, the
overall residence time in Oxfordshire has
remained unchanged. The timing of arrival has
advanced in relation to increasing winter
temperatures in sub-Saharan Africa, whereas the
timing of departure has advanced after elevated
summer temperatures in Oxfordshire. This
finding demonstrates that migratory phenology is
quite likely to be affected by global climate
change and links events in tropical winter
quarters with those in temperate breeding areas.
3
HEATH PHENOLOGY
FOR 797 CLIMATE CHANGE EFFECTS ON NATURAL RESOURCES FALL 2007
Dunn, P.O. and D.W. Winkler. Climate
change has affected the breeding date of tree
swallows
throughout
North
America.
Proceedings of the Royal Society of Biological
Sciences 266: 2487-2490.
Increasing evidence suggests that climate change
has affected the breeding and distribution of
wildlife. If such changes are due to global
warming, then we should expect to see largescale effects. To explore for such effects on
avian reproduction, we examined 3450 nest
records of tree swallows from across North
America. The egg-laying date in tree swallows
advanced by up to nine days during 1959 to 1991.
This advance in phenology was associated with
increasing surface air temperatures at the time of
breeding. Our analysis controlled for several
potentially confounding variables such as
latitude, longitude, breeding density and
elevation.We conclude that tree swallows across
North America are breeding earlier and that the
most likely cause is a long-term increase in
spring temperature.
Fitter, A.H. and R.S.R Fitter. 2002. Rapid
changes in flowering time in British plants.
Science 296: 1689-1691.
The average first flowering date of 385 British
plant species has advanced by 4.5 days during
the past decade compared with the previous four
decades: 16% of species flowered significantly
earlier in the 1990s than previously, with an
average advancement of 15 days in a decade. Ten
species (3%) flowered significantly later in the
1990s than previously. These data reveal the
strongest biological signal yet of climatic change.
Flowering is especially sensitive to the
temperature in the previous month, and springflowering species are most responsive. However,
large interspecific differences in this response
will affect both the structure of plant
communities and gene flow between species as
climate warms. Annuals are more likely to flower
early than congeneric perennials, and insectpollinated species more than wind-pollinated
ones.
Gibbs, J.P. and A.R. Breisch. Climate warming
and calling phenology of frogs near Ithaca, New
York, 1900–1999. Conservation Biology 15:
1175-1178.
Because ambient temperature strongly influences
reproduction in frogs, the seasonal timing of frog
calling provides a sensitive index of biotic
response to climate change. Over the last century,
daily temperatures increased during 5 of the 8
months key to gametogenesis in frogs and toads
near Ithaca, New York ( U.S.A.). Earliest dates
of calling frogs recorded by Albert Hazen Wright
between 1900 and 1912 near Ithaca were
compared to those from the New York State
Amphibian and Reptile Atlas Project for 1990–
1999 for the three counties surrounding Ithaca.
Four species are now calling 10–13 days earlier,
two are unchanged, and none is calling later. The
data suggest that climate has warmed in central
New York State during this century and has
resulted in earlier breeding in some
amphibians—a possible first indication of biotic
response to climate change in eastern North
America.
Parmesan, C. and G. Yohe. 2003. A
globally coherent fingerprint of climate change
impacts across natural systems. Nature 421: 3742.
Causal attribution of recent biological trends to
climate change is complicated because nonclimatic influences dominate local, short-term
biological changes. Any underlying signal from
climate change is likely to be revealed by
analyses that seek systematic trends across
diverse species and geographic regions; however,
debates within the Intergovernmental Panel on
Climate Change (IPCC) reveal several
definitions of a 'systematic trend'. Here, we
explore these differences, apply diverse analyses
to more than 1,700 species, and show that recent
biological trends match climate change
predictions. Global meta-analyses documented
significant range shifts averaging 6.1 km per
decade towards the poles (or metres per decade
upward), and significant mean advancement of
spring events by 2.3 days per decade. We define
a diagnostic fingerprint of temporal and spatial
'sign-switching' responses uniquely predicted by
twentieth century climate trends. Among
appropriate long-term/large-scale/multi-species
data sets, this diagnostic fingerprint was found
for 279 species. This suite of analyses generates
'very high confidence' (as laid down by the IPCC)
that climate change is already affecting living
systems.
Stevens, W.K. 1999. March may be coming
in like a lamb. NY Times: New York, New York.
Visser, M.E. and L.J.M. Holleman. 2001.
Warmer springs disrupt the synchrony of oak
and winter moth phenology. Proceedings of the
Royal Society of Biological Sciences 268: 289294.
4
HEATH PHENOLOGY
FOR 797 CLIMATE CHANGE EFFECTS ON NATURAL RESOURCES FALL 2007
Spring temperatures have increased over the past
25 years, to which a wide variety of organisms
have responded. The outstanding question is
whether these responses match the temperatureinduced shift of the selection pressures acting on
these organisms. Organisms have evolved
response mechanisms that are only adaptive
given the existing relationship between the cues
organisms use and the selection pressures acting
on them. Global warming may disrupt ecosystem
interactions because it alters these relationships
and micro-evolution may be slow in tracking
these changes. In particular, such shifts have
serious consequences for ecosystem functioning
for the tight multitrophic interactions involved in
the timing of reproduction and growth. We
determined the response of winter moth
(Operophtera brumata) egg hatching and oak
(Quercus robur) bud burst to temperature, a
system with strong selection on synchronization.
We show that there has been poor synchrony in
recent warm springs, which is due to an increase
in spring temperatures without a decrease in the
incidence of freezing spells in winter. This is a
clear warning that such changes in temperature
patterns may affect ecosystem interactions more
strongly than changes in mean temperature.
5
Crop yields, food production and
human health
Judy Crawford
EXECUTIVE SUMMARY
There is increasingly clear evidence that
climate change is affecting crops, food production and human health. Warming temperatures
have led to earlier crop planting and earlier fruit
tree flowering. An unusually severe heat wave
during the summer of 2003 destroyed European
food crops and caused an estimated 35,000
deaths. Disease vectors have shifted their ranges
northward, as has allergenic pollen. Although
relatively small right now, for both health and
agriculture, impacts in the future are potentially
huge. Greater health risks are expected through
extreme weather, floods and storms. Fatal heat
waves will be more frequent. Infectious disease
dynamics will change and water sources for
drinking and sanitation will be reduced. Overall,
the spread of disease will be enhanced in a
warming and variable climate. Models show that
at high latitudes, modest increases in temperatures, from 1 – 3 °C, are expected to increase
crop yields and food production. At low latitudes, even slight warming of 1-2 °C is projected
to decrease crop yields. At any latitude, more
than 3 °C decreases crop yields. Agriculture is
tremendously adaptable and effective policies
can help to limit the effects of climate change by
promoting adaptive capacity. Changes in plant
variety, improved water and fertilizer management, changes in timing and location of crops
can all work to minimize negative impacts.
Negative impacts on health are most effectively
met through strengthening of basic public health
infrastructures. This is especially important for
people in low latitude and tropical developing
countries who will suffer most from climate
change even though they have contributed least
to greenhouse gas emissions.
INTRODUCTION
Crop yields, food production and human
health impacts are closely linked issues in climate change. Human survival is dependent upon
an adequate food supply and food production is
dependent upon climate. This paper briefly examines key aspects of the state of the science
underlying these topics. Media perspectives are
explored with examples from contrasting sources
and some considerations for policymakers are
presented.
STATE OF THE SCIENCE
Agriculture and Crops
Agricultural production will most certainly
be impacted by climate change. Whether those
impacts are harmful or beneficial depend largely
upon location. Changes in global temperature,
precipitation and carbon dioxide concentration
are major determinants of agricultural production.
In middle and higher latitudes, warming temperatures may enhance production through
lengthened growing seasons, earlier crop maturation, earlier harvesting, and potentially two cropping cycles. Earlier fruit tree flowering and earlier planting dates for some crops have already
been observed in Europe. [1] With warmer
temperatures, crops may be planted further north,
although there are many uncertainties related to a
northward shift of crops. Along with the plants,
pests, weeds and plant diseases are expected to
expand their northern ranges, and soil fertility
may be an issue. Increased precipitation at high
latitudes is projected, while reduced precipitation
is expected at lower and mid-latitudes. Also at
lower latitudes, increased temperatures may
cause drier soils and heat stress on plants. These
conditions, especially for crops that are already
near their maximum temperatures, translate into
reduced plant growth, crop production and food
supply. [2]
The carbon dioxide effect or ‘fertilization’
refers to the stimulation of photosynthesis at
increased concentrations of CO2. The response
varies according to a plant’s photosynthetic
pathway. Experiments with C3 plants, which
include the majority of plants and crops such as
wheat, rice, soybeans and barley, show yield
increases of 10 – 20% at CO2 concentrations of
550 ppm. [1] C4 plants, including corn, sugarcane, sorghum and millet are less responsive,
with increased yields of less than 10%. Precipitation and temperature changes modify or limit
the CO2 effect, so that under actual field conditions, yields are uncertain. The impact of extreme weather events on crops is another area of
uncertainty. Increased frequency and intensity of
storms, heavy rainfall and heat waves are expected, however their impacts are difficult to
project. The European heat wave during the
summer of 2003 illustrates the substantial effect
of extreme temperatures, in this case 6 °C above
average. In France and Italy, many crops were
CRAWFORD CROPS, HUMAN HEALTH
FOR 797 CLIMATE CHANGE EFFECTS ON NATURAL RESOURCES FALL 2007
reduced by 30% or more and total losses were
estimated at 19 billion dollars. [1] Crop losses
from extreme weather may outweigh positive
effects from warming and CO2. Results from
over 69 studies modeling the response of cereal
yields to climate change produced the following
key conclusions and projections: In mid to high
latitudes, a warming of 1 – 3 °C, along with a
CO2 increase and rainfall changes, benefits crop
yields. However, even slight warming of 1 -2 °C
decreases yields for all major cereals in seasonally dry and low latitude areas. Further warming
at any latitude is more negative. Overall global
food production then is projected to increase
with temperatures 1-3 °C, but decreases beyond
that. [1] Models of climate and global crop
yields are highly complex, yet Lobell developed
a simple relationship between growing season
temperatures, precipitation and crop yields. [3]
The study reports a negative global yield for
wheat, maize and barley with increased temperatures. It also estimates the costs of the negative
impact on yields for these crops from 1980 –
2000 at roughly $5 billion per year.
Historically, agricultural has been highly
adaptable and productive. Changes in plant varieties, fertilization, water management, planting
times and pest and pathogen management have
brought steady increases in world crop yields.
Adaptation to climate change will be necessary.
Adaptive capacity is greatest in developed countries where resources are available. Developing
countries and subsistence farmers will be highly
challenged.
Human Health
Climate change can impact human health
through direct and indirect pathways. Changes in
temperature, precipitation, sea-level rise and
extreme events are capable of causing direct adverse effects such as heat-related illness, drowning from floods, and traumatic injury during
storms. Indirect effects can occur through climate-related changes in air quality, water quality,
food availability, ecosystems, industry and economy. Currently, human health impacts are believed to be in the early stages, with observations
and evidence of change limited to three key areas:
1)
Warming temperatures are believed to be
related to altered distributions of disease
vectors, including changes in tick distribution and tick-borne infections in Europe.
2)
An earlier onset of the spring allergenic
pollen season has been noted in the North-
ern Hemisphere with length of the pollen
season increased also.
3)
An increase in heat wave related deaths has
been documented. [4]
The same 2003 European heat wave that
destroyed crops was responsible for an estimated
35, 000 deaths. [5] Important risk factors for
heat-related deaths include age (elderly and children), urban location, poverty, and social isolation. [6] Although European health care systems are sophisticated, public health response to
the heat wave was inadequate and few preventive
measures were taken to reduce heat-related mortality. With warming temperatures, more heat
waves are projected, along with continued range
expansions for disease vectors and pollen. [7]
Ground level ozone, a ‘summertime’ pollutant, is formed by the reaction of nitrogen oxides, volatile organic compounds, sunlight and
heat. Ozone is an irritant gas associated with
adverse health effects such as pneumonia,
asthma, other respiratory diseases and premature
death. Warming temperatures are expected to
increase airborne ozone concentrations. [4]
Food insecurity arises from changes in agricultural systems as outlined above. Drought
and malnutrition are projected for lower latitude
areas already water-stressed including those in
sub-Saharan Africa, south Asia, and tropical areas of Latin America. In the same locations,
water scarcity is expected to cause decreased
efficiency of sewers and contamination of water
supplies resulting in increased diarrheal diseases,
especially among children. [7] On the other hand,
too much water, from flooding and storms, is
associated with water-borne and other disease
outbreaks. Heavy rainfall can transport microbial and toxic agents and mobilize rodent populations. After rains or floods, mosquito populations
may increase explosively with a resulting increase in mosquito borne diseases.
Some health benefits are expected from
climate change.
Fewer cold-related deaths
should result from warming temperatures. Infectious disease vectors, including malarial mosquitoes, will likely have some contraction in ranges
and transmission seasons. These positive effects
are small however, and the overall balance of
health impacts is overwhelmingly negative. [4]
2
CRAWFORD CROPS, HUMAN HEALTH
FOR 797 CLIMATE CHANGE EFFECTS ON NATURAL RESOURCES FALL 2007
PERSPECTIVES IN THE MEDIA AND PUBLIC
POLICY
Mainstream media perspectives on climate
change appear to be shifting even as of this writing. The Nobel prize awarded to the IPCC
committee and Al Gore likely adds greater authority and credibility to the committee’s work.
The Draft Synthesis Report of the IPCC Fourth
Assessment has been out for three days now and
most media reports appear to accept and promote
the IPCC as the undisputed authority on climate
change. Articles covering the Draft Synthesis
report in the New York Times and Washington
Post did not even mention alternate views on
climate change. With the increasing authority of
the IPCC, it is possible we will see less mainstream media coverage of climate skeptics.
Alternate views do exist however, for example, the newspaper “Environment and Climate
News” published by the Heartland Institute.
According to their website, the organization’s
mission is to promote free-market solutions to
social and economic problems, including marketbased approaches to environmental protection.
An October, 2007 article, “Health Fears About
Global Warming Are Unfounded”, argued that
warmer temperatures are healthier because of
fewer cold-related deaths. [8] The article neglects to mention that cold benefits will not offset all of the negative effects from heat and focuses only on developed countries. Supporting
studies are discussed, but citations are not given,
so they cannot be identified. In all, this is an
opinion piece containing selective information,
but with the appearance and flow of a sciencebased article. Because it looks and sounds like
science, it may influence some readers, especially those who do not understand peerreviewed literature.
CONSIDERATIONS FOR POLICYMAKERS
In the human health area, policies that serve
to strengthen public health infrastructures are
critically important. A comprehensive strategy
to support public health internationally will be
most effective in preparing for and responding to
climate-related health impacts. Because health
impacts are only just emerging, there is time to
develop public health capacity. This is particularly important for developing nations, who are
most vulnerable. Strong public health organizations are actively involved in disease surveillance, sanitation programs, emergency preparedness and response, water and air pollution con-
trol, immunization programs, training of health
professionals and community health education.
These are the most important and cost-effective
measures available, especially for developing
countries. There is really no downside to public
health investment: life expectancy improves,
maternal, infant and child mortalities declines,
quality of living improves, infectious disease
rates decline along with many other benefits.
Climate change adds further urgency to the need
to develop basic preventive public health programs. Developed countries also need policies
that will rebuild existing public health programs.
Inadequate public health response to extreme
weather events such as hurricane Katrina in the
US and the European heat wave demonstrate that
these organizations were clearly not prepared.
In addition, policies should promote research and
development of technologies that will protect
people. Improvements in housing, air conditioning, water purification and pest control will
all be useful for responding to climate based
health impacts. With anticipated water scarcity,
it is important to have policies and a solid regulatory framework for protection of water resources and water quality.
In the agricultural area, policies that promote adaptive capabilities are essential. In order
to maintain crop yields during climate change,
farmers will need to respond rapidly with
changes in plant variety, water and fertilization
practices, and timing and location of crops. Such
adjustments are most difficult for small farmers;
policies should support farmers in vulnerable
locations where food shortages are expected.
Investment in agricultural research and training
is important as is access to credit for capital improvements. Financial incentives, subsidies, and
crop insurance are other measures that may be
part of an overall strategy to support adaptation
in agriculture. Regulatory structures that protect
and preserve land and water resources are also
important.
Finally, policymakers must be aware of a
basic inequity related to climate change; countries that have generated the least greenhouse gas
emissions will bear most of the negative impacts
in health and agriculture. A strategy for compensation and support should be considered.
REFERENCES
1. Easterling, W.E., et al., Food, fibre and
forest products, in Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribu3
CRAWFORD CROPS, HUMAN HEALTH
FOR 797 CLIMATE CHANGE EFFECTS ON NATURAL RESOURCES FALL 2007
tion of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on
Climate Change. 2007, Cambridge University
Press: Cambridge. p. 273-313.
2. Rosenzweig, C. (2003) Climate Change
and Agriculture: Mitigation and Adaptation.
Senate Committee on Environment and Public
Works Subcommittee on Clean Air, Climate
Change, and Nuclear Safety, Available at:
http://epw.senate.gov/108th/Rosenzweig_070803
.htm
3. Lobell, D.B. and C.B. Field (2007)
Global scale climate-crop yield relationships and
the impacts of recent warming. Environ Res. Lett
2, DOI: 10.1088/1748-9326/2/1/014002
Abstract - Changes in the global
production of major crops are important drivers
of food prices, food security and land use decisions. Average global yields for these commodities are determined by the performance of crops
in millions of fields distributed across a range of
management, soil and climate regimes. Despite
the complexity of global food supply, here we
show that simple measures of growing season
temperatures and precipitation—spatial averages
based on the locations of each crop—explain
~30% or more of year-to-year variations in
global average yields for the world's six most
widely grown crops. For wheat, maize and barley,
there is a clearly negative response of global
yields to increased temperatures. Based on these
sensitivities and observed climate trends, we
estimate that warming since 1981 has resulted in
annual combined losses of these three crops representing roughly 40 Mt or $5 billion per year, as
of 2002. While these impacts are small relative
to the technological yield gains over the same
period, the results demonstrate already occurring
negative impacts of climate trends on crop yields
at the global scale Changes in the global production of major crops are important drivers of food
prices, food security and land use decisions. Average global yields for these commodities are
determined by the performance of crops in millions of fields distributed across a range of management, soil and climate regimes. Despite the
complexity of global food supply, here we show
that simple measures of growing season temperatures and precipitation—spatial averages based
on the locations of each crop—explain ~30% or
more of year-to-year variations in global average
yields for the world's six most widely grown
crops. For wheat, maize and barley, there is a
clearly negative response of global yields to in-
creased temperatures. Based on these sensitivities and observed climate trends, we estimate
that warming since 1981 has resulted in annual
combined losses of these three crops representing roughly 40 Mt or $5 billion per year, as of
2002. While these impacts are small relative to
the technological yield gains over the same period, the results demonstrate already occurring
negative impacts of climate trends on crop yields
at the global scale
4. Confalonieri, U., et al., Human health.
Climate Change 2007: Impacts, Adaptation and
Vulnerability. , in Contribution of Working
Group II to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change,
M.L. Parry, et al., Editors. 2007, Cambridge
University Press: Cambridge. p. 391-431.
5. Vandentorren, S., et al., Mortality in 13
French cities during the August 2003 heat wave.
Am J Public Health, 2004. 94(9): p. 1518-20.
Abstract - We observed the daily
trend in mortality rates during the 2003 heat
wave in 13 of France's largest cities. Mortality
data were collected from July 25 to September
15 each year from 1999 through 2003. The conjunction of a maximum temperature of 35 degrees C and a minimum temperature of 20 degrees C was exceptional in 7 cities. An excess
mortality rate was observed in the 13 towns, with
disparities from +4% (Lille) to +142% (Paris)
6. McGeehin, M.A. and M. Mirabelli, The
potential impacts of climate variability and
change on temperature-related morbidity and
mortality in the United States. Environ Health
Perspect, 2001. 109 Suppl 2: p. 185-9.
Abstract - Heat and heat waves are projected to increase in severity and frequency with
increasing global mean temperatures. Studies in
urban areas show an association between increases in mortality and increases in heat, measured by maximum or minimum temperature, heat
index, and sometimes, other weather conditions.
Health effects associated with exposure to extreme and prolonged heat appear to be related to
environmental temperatures above those to
which the population is accustomed. Models of
weather-mortality relationships indicate that
populations in northeastern and midwestern U.S.
cities are likely to experience the greatest number of illnesses and deaths in response to changes
in summer temperature. Physiologic and behavioral adaptations may reduce morbidity and mortality. Within heat-sensitive regions, urban popu4
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FOR 797 CLIMATE CHANGE EFFECTS ON NATURAL RESOURCES FALL 2007
lations are the most vulnerable to adverse heatrelated health outcomes. The elderly, young
children, the poor, and people who are bedridden
or are on certain medications are at particular
risk. Heat-related illnesses and deaths are largely
preventable through behavioral adaptations, including the use of air conditioning and increased
fluid intake. Overall death rates are higher in
winter than in summer, and it is possible that
milder winters could reduce deaths in winter
months. However, the relationship between winter weather and mortality is difficult to interpret.
Other adaptation measures include heat emergency plans, warning systems, and illness management plans. Research is needed to identify
critical weather parameters, the associations between heat and nonfatal illnesses, the evaluation
of implemented heat response plans, and the effectiveness of urban design in reducing heat retention.
7. Patz, J.A. and R.S. Kovats, Hotspots in
climate change and human health. BMJ, 2002.
325(7372): p. 1094-8.
8. Singer, S.F. and D.T. Avery, Health
Fears About Global Warming are Unfounded, in
Environment and Climate News. October 2007.
p.10.
5
Observations and Predictions for
the Northeast
Kristin Cleveland
EXECUTIVE SUMMARY
In recent years, New York and other
northeastern states (Pennsylvania, New Jersey,
and the New England states) have been
experiencing a variety of "… changes [that] are
consistent with those expected to be caused by
global warming," (UCS, 2000, p. ix). This paper
identifies several of these current natural
resource changes and highlights some potential
future changes, focusing on changes that in turn
will likely affect public health, alter economic
traditions and regional identity, and have an
impact on water resources in New England and
in New York's Catskill Mountain region. In
addition, the ways in which information about
changes to the Northeast's natural resources is
presented in the media and to public decision
makers are analyzed in light of suggestions from
several communication and public education
scholars.
INTRODUCTION
A 2007 Gallup Panel poll reveals that
while the majority of Americans are aware of
and somewhat concerned about global warming,
"only a small fraction of the public names global
warming in unaided measures of perceived
problems facing the nation or as a top
government priority," (Saad). The Gallup Panel
found this relatively low ranking of the climate
change issue to be due at least in part to the fact
that Americans perceive global warming effects
to be distant, rather than likely to occur within
the next few decades. Numerous other factors are
also likely to contribute to this low ranking,
including variations in political affiliations (Saad,
2007) and other interpretive communities
(Leiserowitz, 2005), the manner in which climate
change is portrayed in the media (Nisbet, 2007),
and a sense that the potential effects of climate
change will be geographically remote
(Leiserowitz, 2005). Therefore, as a step towards
learning how to improve communication of
scientific information to better help Americans
relate to the issues of climate change, this paper
will focus on climate change impacts in the
northeastern United States, examining two
scientific studies concerning water resources in
New York and New England and two sections of
a Union of Concerned Scientists report related to
the Northeast. In addition, these reports and
articles will be discussed in terms of
communication theory's "framing" and the "twostep flow of popularization" model (Nisbet &
Mooney, 2007; Nisbet, 2007).
STATE OF THE SCIENCE
In 2007 the Northeast Climate Impacts
Assessment (NECIA) team reported on current
and predicted impacts of climate change for the
northeastern region of the United States (UCS
NY, 2007; UCS Summary, 2007). Some changes
already observed are as follows:
More
frequent
days
temperatures above 90ºF
with
- A longer growing season
- Less winter precipitation falling as
snow and more as rain
- Reduced snowpack and increased
snow density
- Earlier breakup of winter ice on
lakes and rivers
- Earlier spring snowmelt resulting in
earlier peak river flows
- Rising sea-surface temperatures and
sea levels (UCS Summary, 2007, ix)
The NECIA reports also identify changes
predicted to occur to the region's natural
resources by mid- or late-century as a result of
changes in climate regimes, based on lower- and
higher-emissions scenarios. These changes are
likely to alter, and in some cases threaten, the
region's social identity, its traditional economic
base, and the health of the region and its
inhabitants.
Noting, "[t]he character and economy of
the Northeast have been profoundly shaped over
the centuries by its varied and changeable
climate," the NECIA report observes that
changes to the region's climate are likely to alter
both this character, which is closely tied to
regional identity, and to alter the economy that is
based upon features of that character (USC
Summary, 2007, ix). For instance, based on the
higher-emissions scenario, reductions of
snowfall and shortening of winter temperatures
will most likely eliminate downhill ski
operations from all parts of the region except
western Maine (x). Even the lower-emissions
scenario will "shorten the average ski and
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snowboard seasons, increase snowmaking
requirements, and drive up operating costs" (xi).
In New York State, recent decades have seen a
rise in average annual temperatures of over 1.5ºF,
with winter average temperatures rising 4ºF
(UCS NY, 2007, 1). Predictions for additional
winter temperature increases by the end of this
century are 8ºF-12ºF under the higher emissions
scenario, and 4ºF-6ºF under the lower scenario
(1-2). Such increases would lead to more of New
York's winter precipitation falling as rain rather
than snow, and more winter precipitation overall
(approximately 20-30% increase under the lower
scenario, and slightly more under the higher
scenario) (2). This will reduce winter ski and
snowmobile seasons in New York's Adirondack
Mountain region. Skiing, snowmobiling, and
other snow-related tourism is an important
component of the Adirondack region's winter
economy (5).
Another character-economy alteration
relates to New England fall-foliage tourism, as
"climate
conditions
suitable
for
maple/beech/birch forests would shift" either out
of the southern parts of the region, if future
greenhouse gas emissions were closer to the
lower-emissions scenario, or would move even
further northward, if the future emissions are
closer to the higher-emissions scenario (USC
Summary, 2007, x-xi). The shift from the
dramatic palette of maple/beech/birch's reds,
oranges and yellows to the more monotone
yellows and browns of the likely successors, the
oak/hickory forests, may reduce the numbers of
people traveling to the Northeast for scenic
tourism, and will certainly alter the identity of
the region.
Regional character and economics will
also be affected by changes to marine and
aquatic habitat, which provides the conditions
for the current fishing industry. The NECIA
team reports that under the higher-emissions
scenario, the predicted "increasing water
temperatures may make the storied fishing
grounds of Georges Bank unfavorable for cod"
(UCS Summary, 2007, x). Even under the loweremissions scenario, Georges Bank will be less
inhabitable for young cod, and under both
scenarios, the Long Island lobster industry will
also decline to the point where it will likely be
gone by mid-century (xi; UCS NY, 2007, 5). In
rivers throughout New England, future climate
changes could potentially lead to reduced river
flows, affecting habitat for the endangered
Atlantic Salmon and other valued northern
species (Huntington, 2003).
In addition to potential changes to the
Northeast's traditional economy and regional
identity, climate change may also be detrimental
to residents' health. Under either emissions
scenario, conditions promoting the growth of
mosquitoes and ticks may lead to increases in the
spread of diseases carried by these animals. Also,
"[t]he number of days over 90ºF is expected to
triple in many of the region's cities, including
Boston, Buffalo, and Concord, NH" (xi). Under
the higher emissions scenario, many Northeast
cities could have at least 14 days over 100ºF
during the average late-century summer (x).
Summer temperatures in New York City are
likely to exceed 100ºF for over 25 days by the
end of the century under the higher scenario
(UCS NY, 2007, 1-2). Such high temperatures in
regions where people are unaccustomed to these
extremes can increase the number of heat-related
deaths, especially to fragile populations such as
the poor, the elderly, and the sick (McGeehin &
Mirabelli, 2001, p. 186). Also, by late-century,
ground-level ozone pollution, which contributes
to respiratory ailments, is expected to rise by
50% under the lower-emissions scenario, and by
200% under the higher-emissions scenario (UCS
Summary, 2007, x-xi). Finally, predicted sea
level rises of at least 1 – 2 feet (lower scenario)
and increasing frequencies of severe flooding for
coastal cities (either scenario) will likely cause
both health and economic problems, at least until
communities adapt to such changes (xi).
Changing temperature patterns and
precipitation regimes in the Northeast may also
affect regional drinking water supplies (Burns,
2006) and water availability for agriculture and
forests, as well as for aquatic species
(Huntington, 2003). In New York's Catskill
region, such changes may alter potential
evapotranspiration rates so that, even with
predicted increases in regional runoff amounts,
the net yield to New York City's water supply
will be reduced (Burns, 2006). New York farms
may have to spend more money on irrigation, as
short-term droughts are likely to occur more
often (UCS NY, 2007, 5). Overall average runoff
rates in New England could drop, although
numerous factors affecting these estimates,
"…the site-specific combination of precipitation,
vegetation, soils, geology, aquifer characteristics,
and microclimate," make it difficult to predict
specific impacts to particular river basins
(Huntington, 2003, 199).
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PERSPECTIVES IN MEDIA AND PUBLIC
POLICY
Matthew Nisbet, a specialist in
communication of scientific information,
observes that the growing number and
accessibility of choices in modern media make
readers increasingly likely to select media
content based on interest preferences and to
select media sources based on political, religious,
or other ideologies. This "fragmented media
system" can lead to "…selective acceptance of
like-minded arguments and opinions," making it
increasingly difficult for readers to attend to a
diversity of information (Nisbet, 2007). Nisbet
recommends three techniques to manage this
information situation in order to get scientific
information to the public. First, explaining that,
"…citizens do not use the news media as
scientists assume," Nisbet and Mooney (2007)
argue, "Without misrepresenting scientific
information on highly contested issues, scientists
must learn to actively 'frame' information to
make it relevant to different audiences."
Framing is a way of making an issue
personally relevant, defining it through
"[organizing] central ideas [and]… giving some
aspects greater emphasis [in order to] …allow
citizens to rapidly identify why an issue matters,
who might be responsible, and what should be
done" (Nisbet & Mooney, 2007). Noting the
prevalence of "science-intensive" messages
provided by researchers, Nisbet and Mooney
explain that "much of the public likely tunes out
these technical messages" and instead attend to
messages that are framed in ways that they can
connect to issues they better understand, such as
"economic development" or "social progress"
(2007). In addition, emphasizing only the
technical details of a study opens up these details
to be interpreted by politicians, business and
industry leaders, and others who have a
particular agenda. Some of the frames that have
been applied to the climate change issue are
"unfair economic burden" and "scientific
uncertainty," which have been countered by the
"catastrophe" frame of drowning polar bears and
destructive hurricanes, which in turn "have
evoked charges of 'alarmism' and further battles"
(Nisbet & Mooney, 2007). Nisbet and Mooney
explain that providing technical information
along with a frame such as "public
accountability" can help media readers to
understand a perspective that suggests their role
and the role of government in dealing with the
implications of that technical information. Nisbet
also recommends branching out from the news to
other genres of popular culture, such as the
entertainment media and "celebrity culture."
Politicians are learning this trick, recognizing
that they can get a wider audience on "The Daily
Show" than on the "MacNeil/Lehrer NewsHour."
Finally, Nisbet explains the "importance of
'opinion-leaders' in … [diffusing]… messages
within local communities." Nisbet recommends:
When "surges" in communication and
public attention are needed – such as surrounding
the release of a future section of the IPCC report
or a major study by the National Academies of
Science – opinion leaders can be activated with
talking points to share in conversations with
friends and co-workers, in emails, in blog posts,
or letters to the editor. These "scientific citizens"
would not formally speak on behalf of or
represent the scientific organization, but instead
their effectiveness would stem from their ability
as co-workers and friends to communicate
climate change in a way that makes it personally
and politically relevant. (Nisbet, 2007)
Some additional alternative methods of
communicating information about climate
change include holding community workshops
and other forms of public information sessions
(Taylor, Gray, & Schiefer, 2006). Such
techniques can be particularly effective in
helping community residents understand and
adapt to the changes that will occur in their local
environment.
CONSIDERATIONS FOR POLICYMAKERS
For policymakers to devise plans to, at a
minimum, manage the effects of climate change
for their constituencies, and perhaps to reduce
some of the potential harmful effects, they need
to have as much information as is practical for
them to work with, and they need to understand
the relevance of various levels of uncertainty and
of variations between studies. The New England
Regional Assessment addresses this issue of
uncertainty and predictive model variation by
recommending "an assessment approach … [that]
allows individual regions or sectors to consider
'what if' cases that reflect educated guesses based
on the nature and importance of specific regional
and sector vulnerabilities." Huntington reflects
this advice in his caution to readers that, "The
value of the empirical relationships [examined in
this study] is in understanding likely average
runoff response for a region rather than
prediction for a specific river basin" (2003,199).
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Policymakers must recognize the value of
"educated guesses," and understandings of
general regional impacts rather than specific
certainties, considering the danger of ignoring
these likelihoods while awaiting certainties and
specifics. For this to happen, scientists must be
willing to explain such values to policymakers.
REFERENCES
Burns, D.A., Klaus, J., & McHale, M.R.
(2007). Recent climate trends and implications
for water resources in the Catskill Mountain
region, New York, USA. Journal of Hydrology,
336(1-2), 155-170.
Abstract: Climate scientists have concluded that
the earth's surface air temperature warmed by
0.6ºC during the 20th century, and that warming
induced by increasing concentrations of
greenhouse gases is most likely to continue in
the 21st century, accompanied by changes in the
hydrologic cycle. Climate change has important
implications in the Catskill region of
southeastern New York State, because the region
is a source of water supply for New York City.
We used the non-parametric Mann-Kendall test
to evaluate annual, monthly, and multi-month
trends in air temperature, precipitation amount,
stream runoff, and potential evapotranspiration
(PET) in the region during 1952-2005 based on
data from 9 temperature sites, 12 precipitation
sites, and 8 stream gages. A general pattern of
warming
temperatures
and
increased
precipitation, runoff, and PET is evident in the
region. Regional annual mean air temperature
increased significantly by 0.6ºC per 50 years
during the period; the greatest increases and
largest number of significant upward trends were
in daily minimum air temperature. Daily
maximum air temperature showed the greatest
increase during May through September.
Regional
mean
precipitation
increased
significantly by 136 mm per 50 years, nearly
double that of the regional mean increase in
runoff, which was not significant. Regional mean
PET increased significantly by 19 mm per 50
years, about one-seventh that of the increase in
precipitation amount, and broadly consistent
with increased runoff during 1952-2005, despite
the lack of significance in the mean regional
runoff trend. Peak snowmelt as approximated by
the winter-spring center of volume of stream
runoff generally shifted from early April at the
beginning of the record to late March at the end
of the record, consistent with a decreasing trend
in April runoff and an increasing trend in
maximum March air temperature. This change
indicates an increased supply of water to
reservoirs earlier in the year. Additionally, the
supply of water to reservoirs at the beginning of
winter is greater as indicated by the timing of the
greatest increases in precipitation and runoff –
both occurred during the summer and fall. The
future balance between changes in air
temperature and changes in the timing and
amount of precipitation in the region will have
important implications for the available water
supply in the region.
Huntington, T.G. (2003). Climate warming
could reduce runoff significantly in New
England, USA. Agricultural and Forest
Meteorology, 117(3-4), 193-201.
Abstract: The relation between mean annual
temperature (MAT), mean annual precipitation
(MAP) and evapotranspiration (ET) for 38
forested watersheds was determined to evaluate
the potential increase in ET and resulting
decrease in stream runoff that could occur
following climate change and lengthening of the
growing season. The watersheds were all
predominantly forested and were located in
eastern North America, along a gradient in MAP
from 3.4ºC in New Brunswick, CA to 19.8ºC in
northern Florida. Regression analysis for MAT
versus ET indicated that along this gradient ET
increased at a rate of 2.85 cmº-1 increase in MAT
(±0.96 cmºC-1, 95% confidence limits). General
circulation models (CGM) using current midrange emission scenarios project global MAT to
increase by about 3ºC during the 21st century.
The inferred, potential, reduction in annual
runoff associated with a 3ºC increase in MAT for
a representative small coastal basin and an inland
mountainous basin in New England would be
11-13%. Percentage reductions in average daily
runoff could be substantially larger during the
months of lowest flows (July – September). The
largest absolute reductions in runoff are likely to
be during April and May with smaller reduction
in the fall. This seasonal pattern of reduction in
runoff is consistent with lengthening of the
growing season and an increase in the ratio of
rain to snow. Future increases in water use
efficiency (WUE), precipitation, and cloudiness
could mitigate part or all of this reduction in
runoff but the full effects of changing climate on
WUE remain quite uncertain as do future trends
in precipitation and cloudiness.
4
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Leiserowitz, A.A. (2005). American risk
perceptions: is climate change dangerous? Risk
Analysis 25(6), 1433-1442.
McGeehin, M.A. & Mirabelli, M. (2001).
The potential impacts of climate variability and
change on temperature-related morbidity and
mortality in the United States. Environmental
Health Perspectives 109(2), 185-189.
New England Regional Assessment (1999).
NERA Model White Paper. Retrieved from
www.necci.sr.unh.edu/reports.html
on
November 12, 2007.
Nisbet, M. (2007). A "two-step flow of
popularization" for climate change: recruiting
opinion leaders for science. Retrieved October
24, 2004 from the Community for Skeptical
Inquiry
website:
http://www.csicop.org/scienceandmedia/climate.
Saad, L. (2007, March). To Americans, the
risks of global warming are not imminent.
Retrieved
11/12/07
from
www.gallup.com/poll/26842/Americans-RisksGlobal-Warming
Taylor, M.E., Gray, P.A., & Schiefer, K.
(2006). Helping Canadians adapt to climate
change in the Great Lakes coastal zone. The
Great Lakes Geographer, 13(1), 14-25.
Abstract: As global warming increases, Great
Lakes coastal communities will be subjected to
significant climate changes driven by increasing
temperature, changing precipitation and wind
patterns, and a potential increase in the
frequency of severe events such as windstorms
and ice storms. Climate change will impact all
life in every ecosystem, and people who live and
work in these systems will need to adapt in a
variety of ways. In response, a number of
agencies and organizations have partnered to
assist Great Lakes coastal communities in their
efforts to identify and assess adaptation options.
To date, workshops have been completed in
Belleville (Lake Ontario) and Parry Sound (Lake
Huron). This paper reviews some of the known
and potential impacts that will result in our near
Presqu'ile Provincial Park, Lake Ontario and in
Sturgeon Bay, Lake Huron, and proposes a
checklist of actions that could provide the basis
for an adaptation protocol.
Union of Concerned Scientists (2007).
Northeast
Climate
Impacts
Assessment
Executive
Summary. Retrieved September,
2007 from www.climatechoices.org.
5
A survey of climate change
mitigation technologies in Pacala
and Socolow (2004)
Tony Eallonardo
EXECUTIVE SUMMARY
It is now widely known and well accepted
that anthropogenic green house gas emissions are
modifying the global climate in a syndrome of
ways described as The Greenhouse Effect or
Climate Change. There is also broad based
agreement that unless business-as-usual activities
are radically changed over the next decades,
significant alteration of the biosphere is likely
(IPCC 2007a,b). The risk of inaction on climate
change, which briefly stated amounts to
increased stress to hundred of millions of
humans (IPCC 2007b), outweighs the cost of
action. The IPCC (2007c) states that the cost of
stabilizing atmospheric CO2 at approximately
double pre-industrial levels will range from 0.22.5% of global GDP. Under modeling scenarios
where mitigation improves market efficiency,
GDP gains are predicted (IPCC 2007c). Pacala
and Socolow (2004) state that humanity has the
technological know-how to limit CO2 emissions
to approximately a doubling of pre-industrial
levels over the next 50 years and they provide a
list of potential mitigation solutions. This paper
explores technologies itemized in Pacala and
Socolow (2004), namely, carbon capture and
storage, hydrogen fuels, biomass derived ethanol,
and conservation tillage.
INTRODUCTION
Mitigation in the context of global
environmental issues
Greenhouse gas (aka Carbon) mitigation is
any activity that reduces green house gas
emissions to the atmosphere. While a variety of
carbon mitigation technologies are currently
available and will be discussed further below, it
is worth noting that ultimately most (if not all)
environmental issues are driven by the increasing
human population and that we are met at the
outset with the following irony:
Since increasing human population is the
ultimate driver of environmental issues, there is a
need to reduce the global population growth rate.
Human population growth rate is negatively
correlated with GDP (the so-called ‘demographic
transition,’ Goldstein 1999). Yet production of
GDP is positively correlated with fossil fuel use
(Cleveland et al. 1984). Assuming that the
relationship exemplified in the demographic
transition is real, then the global standard of
living (e.g. GWP, gross world product) must be
increased in order to stabilize our environmental
impacts (not to mention other ethical and
sovereignty issues). Yet bringing the global
standard of living up to levels enjoyed by
developed nations would lead to massive
increases in green house gas emissions.
Therefore, another way of considering carbon
mitigation is the decoupling of wealth production
from fossil fuel use. Pacala and Socolow (2004)
provide a framework for doing just that.
Pacala and Socolow (2004) state that
humanity has the technological know-how to
limit CO2 emissions to approximately a doubling
of pre-industrial levels, but what needs to happen
is a scaling up of a suite of these technologies.
Stabilizing atmospheric concentrations of CO2
near 500 ppm requires that global emissions be
held at about 7 Pg C/yr, while business as usual
will put us at about 14 Pg C/yr emissions by
2054. The authors envision a “stabilization
triangle” comprised of the difference between
these two emission rates over a 50 year time span.
They divide the stabilization triangle into seven
potential mitigation solutions (e.g. wedges) that
each represents “an activity that reduces
emissions to the atmosphere that starts at zero
today and increases linearly until it accounts for
1 Pg C/yr of reduced carbon emissions in 50
years.” Each wedge totals 25 Pg C to be
mitigated over 50 years. Citing the fact that gross
world production has increased by 3% while
energy consumption has increased by only 2%,
the authors indicate that the global economy has
been on a trajectory of decarbonization since the
time of Cleveland et al. (1984). This decreasing
energy intensity (emissions/$GDP) has led to
avoiding the need for three additional wedges.
The authors present what they call is a nonexhaustive list of 15 options for the seven
wedges:
1)
Increasing transportation fuel economy
from 30 to 60 mpg
2)
Reduce fuel use by halving the miles driven
3)
Reduce building emissions by 20%
4)
Increase coal plant efficiency from today’s
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5)
Replace coal with gas by increasing gas
power production by 300%
6)
Capture CO2 at power plant: apply carbon
capture and storage (CCS) at 800 GW of
coal or 1600 GW of natural gas
7)
Capture CO2 at hydrogen plant: apply CCS
to 250 Mt H2/yr from coal or 500 Mt H2/yr
from natural gas
8)
Capture CO2 at a coal to synfuels plant:
apply CCS to the production of 30 million
barrels/day of synfuels production
9)
Increase nuclear capacity by 100%
10) Replace coal with wind: increase wind
capacity by 4900%
11) Replace coal with photovoltaics (PV):
increase PV by 69900%
12) Replace hybrid cars with wind derived H2
cars: increase wind capacity by 9900%
13) Convert 1/6th of earth’s cropland to biofuel
production
14) Stop tropical deforestation and double the
current rate of afforestation projects
15) Apply conservation tillage to all cropland
I will further explore key technologies
associated with these potential wedges: CCS,
hydrogen fuel, biofuels, and conservation tillage.
These technologies were chosen for further study
due to their broad applicability and/or potentially
controversial issues. While Pacala and Socolow
(2004) do not explicitly discuss interactions
between wedges, I will aim to reveal potential
synergies/controversies in the ‘State of the
Science’ section.
STATE OF THE SCIENCE
Carbon capture and storage
Carbon capture and storage (CCS) is the
collection, purification, liquification and
placement of carbon dioxide emissions in
geologic reservoirs or the oceans. Significant
questions remain at all steps in this process.
Since the heavy ecological toll of increasing
oceanic carbon concentrations is well known, I
will not consider the oceans as a potential
reservoir. Given the high relative abundance and
inexpensiveness of coal, Rau and Caldiera (2007)
state that two coal-fired power plants are to be
built every two weeks over the next 25 years.
Therefore, CCS will likely be a central
component of wedge portfolio. For one wedge’s
worth of CCS, approximately 120 million barrels
of liquid CO2 would need to be buried every day
(Shepard and Socolow 2007). While there is
evidence that there is space for the several
hundred years of CO2 emissions (Shepard and
Socolow 2007, Damen et al. 2006), at least
several hundred CCS systems would have to
come on line in the next 50 years to stabilize
emissions (IPCC 2005).
There are two relatively well-known
methods by which carbon capture can occur: the
so-called pulverized coal (PC) process where the
carbon is removed post combustion and the
integrated gasification combined cycle (IGCC)
where the carbon is removed after the coal is
gasified but before it is burned. In most current
scenarios, the PC process uses the solvent
monoenthanolamine (MEA) to capture CO2 in
the gas, however significant heating is required
to remove the captured CO2 from the MEA for
compression and storage. Due to this inefficiency,
many other carbon collection methods ranging
from nano-technology biological catalysts are
being tested (Kintisch 2007a), but in the mean
time, IGCC process appears to be the favored
technology (Kintisch 2007b).
Risks and management implications
associated with transport, injection and storage
of CO2 are as follows (Damen et al. 2006):
1)
The main risk associated with transporting
and injecting CO2 are leaks in transport and
well head failures. However, given the
positive track-record of existing CO2
pumping operations for oil recovery, the
risk is quite low.
2)
Risks in geological storage include: leaks,
earthquakes and other ground movements,
and damage to freshwater aquifers. Model
results suggest that CO2 escaping from
failed geological reservoirs located 7001000 m below the earth’s surface would
take at least 5,500 and possibly up to
500,000 yr to surface. While “cap rock”
failures may occur in geological reservoirs,
number of secondary processes (e.g. CO2
capture in liquids, fossil fuels, heavy soils).
The strongest consideration for CCS
activities should be given to sites with the
greatest number and extent of these
secondary capture mechanisms. While CO2
can damage the integrity of clay shales, the
authors site other studies that have shown
that mineral precipitation may decrease
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CO2 permeability, and variety of seismic
issues can be avoided by keeping storage
pressure below the geostatic pressure.
3)
4)
Potential “point sources” for CO2 leakage
are abandoned wells that have been
decommissioned improperly or that have
deteriorated. Abandoned wells represent
one of the more significant CCS risks,
however at least this risk can be managed
through knowing the location and
conditions of all decommissioned wells on
site, and site selection should factor out
areas with excessive wells.
Considerable uncertainly remains in
regards to polluting fresh water aquifers
with brine displaced from CCS operations.
A potential natural analog for a worst case
scenario was in 1986 when the hypolimneon of
Lake Nyos, Cameroon became supersaturated
with volcanic CO2 and rapidly overturned. This
event released CO2 that settled into a nearby
village and killed approximately 1700 people.
Loss of human life on this scale would likely not
occur from a failure from geological reservoir
unless the CO2 leaked into a surface water body.
Therefore site selection committees should also
factor out any sites with surface water bodies
that could receive gas leakage. The Lake Nyos
example shows that type of the type of the
release (in terms of rapidity and topography (In
the Lake Nyos example the gas cloud was able to
remain intact and settle in the village)) is likely
more important than the volume of release when
considering short term human health impacts
(Damen et al. 2006).
Hydrogen fuel: attractive potential with a
CCS requirement and logistical issues
Since the transport sector is responsible for
a significant amount of the increase in world oil
demand over the last 30 years (Difiglio and
Gielen 2007), zero-carbon fuels could be an
important mitigation tool. While hydrogen has
well-known advantages such as zero carbon
emissions and energy independence, it also has
many current disadvantages. For example, low
cost hydrogen production, storage and
conversion
technologies
are
currently
unavailable (Dixon 2007). The most practical
production of hydrogen is from fossil fuel
sources where the conversion efficiency is less
than one, and which would necessitate the
development of CCS (Difiglio and Gielen 2007).
Outstanding issues needing resolution
associated with the following topics:
are
1)
Distribution: At room temperature,
hydrogen occupies 2000-3000 times the
space per energy unit than gasoline does
(Dixon 2007); therefore besides the energy
needed to create hydrogen fuel, energy is
needed to liquefy it.
2)
Technology life span: The Proton Exchange
Membrane (PEM) is largely the preferred
fuel cell type, but it is expensive and needs
replacement every 31,000 miles (Difiglio
and Gielen 2007).
3)
Overall cost: The life-cycle analysis of
Difiglio and Gielen (2007) suggests that
significant progress must be made in the
production, transport and use of hydrogen
fuel to reduce what are currently
prohibitive costs.
Difiglio and Gielen (2007) report that the
relative mitigation cost of utilizing fuel cell
vehicles decreases as total driving time increases,
and that passenger cars are, surprisingly, not
used enough to realize mitigation benefits in
terms of dollars. They suggest initiating
hydrogen technologies in trucks, buses, trains,
and airplanes—end uses that have a much greater
annual use.
An alternative view is provided by Lovins
and Cramer (2004). They have designed a fuel
cell vehicle that reduces required propulsive
energy by approximately 66%, which, in their
view, moots any argument on the expense of fuel
cells because the required engines and tanks can
be smaller and more economical.
Biomass ethanol production as an
alternative fuel option
One wedge worth of carbon may be
accounted by the use of biofuels however
bioenergy cropping systems require fossil fuel
inputs, emit non-carbon greenhouse gases, and
entail important ethical questions. Adler et al.
(2007) provide a life cycle assessment of
bioenergy cropping systems. The authors
considered potential biofuel crops for North
America: corn, soy, alfalfa, reed canarygrass,
alfalfa, and hybrid poplar. They found that
combined corn grain and stover harvest had the
highest ethanol yield (8 MJ/m2/yr), with
switchgrass and hybrid poplar tied for second at
(7-8 MJ/m2/yr). When crop inputs and
greenhouse gas emissions were considered,
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switchgrass and hybrid poplar displace the
greatest amount of fossil fuels (150 to 160 g CO2
equivalents/m2/yr). Besides increased machinery
emissions, traditional cropping systems (e.g.
corn, soy) have 100 to 200% greater N2O
emissions and 50% greater CO2 emissions from
the soil than switchgrass and hybrid poplar
systems. Across all cropping systems the greatest
amount of CO2 emissions was associated with
harvesting—up to 80-90% for switchgrass and
hybrid poplar. Therefore, small increases in
harvesting efficiency could have relatively large
effects on the overall system carbon balance.
One wedge of biofuels is 250 x 106
hectares or about 1/6th of total cropland (Pacala
and Socolow 2004). One is left wondering how a
40-50% bigger global population (U.S. Census
Bureau 2006) will be fed on 16% less land by
2050.
Righelato and Spracklen (2007) collated a
variety of life cycle analyses to show that, “In all
cases, forestation of an equivalent area would
sequester two to nine times more carbon over a
30-year period than emissions avoided by the use
of biofuel.” They suggest that forest restoration
should be favored over biofuel production for
this reason. While this suggestion makes sense
for lower latitude areas, it has been shown that
reforestation in temperate zones has a net
radiative forcing due to the relatively low albedo
of forests (Myre and Myre 2003). One must also
consider that forests periodically burn. Therefore
the most logical solution may be to utilize land
area for biofuel production where forest radiative
forcing would outweigh carbon sequestration
effects or where forests fires are relatively
frequent; and during biofuel production utilize
agricultural RMPs (described next) to facilitate
carbon storage in the soil.
Recommended management practices (aka
Conservation Tillage)
While approximately 300 Pg of C have
been emitted by fossil fuel combustion over the
last century an additional 150 GT has been from
agricultural soil emissions (Rosenzweig and
Tubiello 2007). The causes of agricultural CO2
emissions are well known: soil drainage,
plowing, removal of crop residue, fire, inorganic
amendments (e.g. lime), and erosion (Lal 2007).
Agronomists have developed recommended
management practices (RMPs) that increase soil
quality and in doing so reduce net carbon
emissions and increase crop yield. RMPs are: notill farming, incorporation of forages into the
rotation cycle, and use of manure/biosolids for
soil amendment instead of inorganic fertilizers.
RMPs also reduce climate change stresses on
crops by increasing soil quality.
Recommended management practices result
in increased formation of stable soil aggregates,
increased soil humification, increased eluviation
of soil C to subsoils, and increased leaching of
carbonates to groundwater (which is also
considered a form of C sequestration (Raymond
and Cole 2003)). The greatest C sequestration
potential is in relatively cool and humid
environments on relatively heavy textured soils
that also have sufficient levels of humus building
blocks (e.g. N, P, and S). On the other hand,
structurally reduced soils (e.g. those dominated
by kaolinite clays) that are nutrient-poor and in
warm regions have the greatest capacity to
volatilize carbon. The global mean rate of soil C
sequestration for conversion of conventional to
no-till cropping is 400-600 kg/ha/yr which
equates to a 0.6 to 1.2 Pg C/yr across all crop
land (Rosenzweig and Tubiello 2007). This
sequestration rate is consistent with “one wedge”
of carbon or 1 Pg C sequestered per year in
Pacala and Socolow (2004).
PERSPECTIVES IN THE MEDIA AND PUBLIC
POLICY
Time magazine recently published a
special section: Global Warming (Knauer 2007).
The magazine is packed full of striking, highly
effective images related to the sources,
environmental impacts and mitigation solutions
of climate change. There is a consistent theme
across the magazine’s articles that climate
change’s sources are anthropogenic, the
environmental impacts are and have been
coming into fruition, but that mitigation
solutions are both practical, economical, and
available to both average citizens and industry.
The magazine features “FAQs” sections for the
climate change neophytes and puts answers to
complex climate questions in understandable,
informative terms.
In regards to mitigation, the magazine is
packed with examples of mitigation solutions
across all sectors of the economy; incorporated
with this effort are a series of profiles on
progressive individuals, e.g. “Pioneers of
Alternative Energy,” which makes real the
sometimes illusive vision of how the world can
adapt to and mitigate climate change. On the
other hand, the magazine touts corn ethanol as a
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prospective mitigation solution, but the scientific
evidence (e.g. Adler et al. 2007) does not support
this position. The magazine lists 51 actions
individuals can take and communicates the
effectiveness and cost of each action in simple
diagrammatic terms. Lacking from this magazine
is more emphasis on forcing politicians to take
up the climate change issue in large measure.
Voting for leaders who will be active on climate
issues is an important mitigation activity that
individuals can perform.
CONSIDERATIONS FOR POLICYMAKERS
The risk of inaction on climate change,
which briefly stated amounts to increased stress
to hundred of millions of humans (IPCC 2007b)
outweighs the cost of action. The IPCC (2007c)
states that the cost of stabilizing atmospheric
CO2 at approximately double pre-industrial
levels will range from 0.2-2.5% of global GDP.
Upfront costs of implementing infrastructural
changes will be almost completely recouped over
long term increases in efficiency. When
economic models assume that current energy
market conditions are non-optimal (e.g. that
subsidies obscure real competitive interactions
between commodities), GDP gains are predicted
if models assume that mitigation solutions
improve market efficiencies (IPCC 2007c). In
other words, there is a good overall chance for
money to be made on carbon mitigation if
competitive markets are allowed to determine
which mitigation technologies are best and that
they result in increases in energy efficiency and
productivity.
The biggest economic potentials exist in the
building sector, followed by energy supply and
tied for third are agriculture and industry (IPCC
2007c). In the building sector, 30% of projected
carbon emissions can be avoided through simple,
money-saving energy efficiency options e.g.
more efficient lighting, heating and cooling
systems; improved insulation; solar heating). The
potential for profitable solutions for people,
businesses and governments increases as oil
price increases, and a multi-greenhouse gas
mitigation approach tends to make conversion
less costly (IPCC 2007c). In other words, focus
on the low hanging fruit.
Hydrogen energy—where government
intervention may be useful
Overall, the combined risks associated with
production, distribution and end-use of hydrogen
has lead to the so-called “chicken or the egg”
problem in which potential providers will not
invest in hydrogen if potential consumers can not
be identified and consumers will not purchase a
fuel cell vehicle if the fuel is not reliable and
widely available (Difiglio and Gielen 2007).
Overcoming “chicken or the egg” type problems
will be an ideal opportunity for government
intervention. Government spurred hydrogen use
for mass transit/shipping would establish the
infrastructural framework that consumers expect.
Difiglio and Gielen (2007) report that the relative
mitigation cost of utilizing fuel cell vehicles
decreases as total driving time increases,
therefore the most effective initial use of
hydrogen technologies would be in mass
transit/shipping applications.
Carbon certification systems
One of the key issues arising from the
biofuels, conservation tillage, and CCS
components of Pacala and Socolow (2004) is
that a certification system for carbon
sequestration is needed to set standards, assess
results, and provide an adaptive framework if
standards are not being met. For example, three
issues in regards to soil C sequestration are that:
1)
Soil C eventually saturates
2)
Increasing global temperatures may reduce
soil carbon storage
3)
As agriculture moves north in adapting to
climate change, additional carbon may be
volatilized from previously untilled
grounds
Policy makers should also recognize that
soil C sequestration is not immediate and occurs
over a roughly 40 year window. However, that
lag may be balanced by the fact that RMPs
generally mean less energy intensive approaches
which will also reduce C emissions through
reduced machinery and labor time (Rosenzweig
and Tubiello 2007).
CITED REFERENCES WITH ABSTRACTS
Adler, P.R., S.J. Del Grosso, W.J. Parton.
2007. Life-cycle assessment of net greenhousegas flux for bioenergy cropping systems.
Ecological Applications 17: 675-691.
Abstract: Bioenergy cropping systems could help
offset greenhouse gas emissions, but quantifying
that offset is complex. Bioenergy crops offset
carbon dioxide emissions by converting
atmospheric CO2 to organic C in crop biomass
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and soil, but they also emit nitrous oxide and
vary in their effects on soil oxidation of methane.
Growing the crops requires energy (e.g., to
operate farm machinery, produce inputs such as
fertilizer) and so does converting the harvested
product to usable fuels (feedstock conversion
efficiency). The objective of this study was to
quantify all these factors to determine the net
effect of several bioenergy cropping systems on
greenhouse-gas (GHG) emissions. We used the
DAYCENT biogeochemistry model to assess
soil GHG fluxes and biomass yields for corn,
soybean, alfalfa, hybrid poplar, reed canarygrass,
and switchgrass as bioenergy crops in
Pennsylvania, USA. DAYCENT results were
combined with estimates of fossil fuels used to
provide farm inputs and operate agricultural
machinery and fossil-fuel offsets from biomass
yields to calculate net GHG fluxes for each
cropping system considered. Displaced fossil
fuel was the largest GHG sink, followed by soil
carbon sequestration. N2O emissions were the
largest GHG source. All cropping systems
considered provided net GHG sinks, even when
soil C was assumed to reach a new steady state
and C sequestration in soil was not counted.
Hybrid poplar and switchgrass provided the
largest net GHG sinks, .200 g CO2e-C/m2/yr1
for biomass conversion to ethanol, and .400 g
CO2e-C/m2/yr1 for biomass gasification for
electricity generation. Compared with the life
cycle of gasoline and diesel, ethanol and
biodiesel from corn rotations reduced GHG
emissions by 40%, reed canarygrass by ;85%,
and switchgrass and hybrid poplar by 115%.
Cleveland, C.J., R. Costanza, C.A.S. Hall,
and R. Kaufman. 1984. Energy and the U.S.
economy: a biophysical perspective. Science 225:
890-897.
Damen, K., A. Faaij, and W. Turkenburg.
2006. Health, safety and environmental risks of
underground
storage—overview
of
CO2
mechanisms and current knowledge. Climate
Change 74: 289-318.
Abstract: CO2 capture and storage (CCS) in
geological reservoirs may be part of a strategy to
reduce global anthropogenic CO2 emissions.
Insight in the risks associated with underground
CO2 storage is needed to ensure that it can be
applied as safe and effective greenhouse
mitigation option. This paper aims to give an
overview of the current (gaps in) knowledge of
risks associated with underground CO2 storage
and research areas that need to be addressed to
increase our understanding in those risks. Risks
caused by a failure in surface installations are
understood and can be minimised by risk
abatement technologies and safety measures. The
risks caused by underground CO2 storage (CO2
and CH4 leakage, seismicity, ground movement
and brine displacement) are less well understood.
Main R&D objective is to determine the
processes controlling leakage through/along
wells, faults and fractures to assess leakage rates
and to assess the effects on (marine) ecosystems.
Although R&D activities currently being
undertaken are working on these issues, it is
expected that further demonstration projects and
experimental work is needed to provide data for
more thorough risk assessment.
Difiglio, C., and D. Gielen. 2007.
Hydrogen and transportation: alternative
scenarios. Mitigation and Adaptation Strategies
for Global Change 12: 387-405.
Abstract: If hydrogen (H2) is to significantly
reduce greenhouse gas emissions and oil use, it
needs to displace conventional transport fuels
and be produced in ways that do not generate
significant greenhouse gas emissions. This paper
analyses alternative ways H2 can be produced,
transported and used to achieve these goals.
Several H2 scenarios are developed and
compared to each other. In addition, other
technology options to achieve these goals are
analyzed. A full fuel cycle analysis is used to
compare the energy use and carbon (C)
emissions of different fuel and vehicle strategies.
Fuel and vehicle costs are presented as well as
cost-effectiveness estimates. Lowest hydrogen
fuel costs are achieved using fossil fuels with
carbon capture and storage. The fuel supply cost
for a H2 fuel cell car would be close to those for
an advanced gasoline car, once a large-scale
supply system has been established. Biomass,
wind, nuclear and solar sources are estimated to
be considerably more expensive. However fuel
cells cost much more than combustion engines.
When vehicle costs are considered, climate
policy incentives are probably insufficient to
achieve a switch to H2. The carbon dioxide
(CO2) mitigation cost would amount to several
hundred US$ per ton of CO2. Energy security
goals and the eventual need to stabilize
greenhouse gas concentrations could be
sufficient. Nonetheless, substantial development
of related technologies, such as C capture and
storage will be needed. Significant H2 use will
also require substantial market intervention
during a transition period when there are too few
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vehicles to motivate widely available H2
refueling.
Dixon, R.K. 2007. Advancing towards a
hydrogen energy economy: status, opportunities
and barriers. Mitigation and Adaptation
Strategies for Global Change 12: 325-341.
Goldstein, J. 1999. International relations.
Longman: New York, NY. 672 pp.
IPCC. 2005. Carbon dioxide storage and
capture. Bert Metz, Ogunlade Davidson,
Heleen de Coninck, Manuela Loos and Leo
Meyer (Eds.) Cambridge University Press, UK.
pp 431.
IPCC. 2007a. Summary for policymakers.
In: cClimate change 2007: the physical science
basis. Contribution of working group I to the
fourth
assessment
report
of
the
Intergovernmental Panel on Climate Change
[Solomon, S., D. Qin, M. Manning, Z. Chen, M.
Marquis, K.B. Averyt, M.Tignor and H.L. Miller
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IPCC. 2007b. Summary for policymakers.
In: climate change 2007: impacts, adaptation
and vulnerability. Contribution of working group
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Intergovernmental Panel on Climate Change,
M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J.
van der Linden and C.E. Hanson, Eds.,
Cambridge University Press, Cambridge, UK, 722.
IPCC. 2007c. Summary for policymakers.
In:
climate
change
2007:
mitigation.
Contribution of working group III to the fourth
assessment report of the Intergovernmental Panel
on Climate Change [B. Metz, O.R. Davidson,
P.R. Bosch, R. Dave, L.A. Meyer (eds)],
Cambridge University Press, Cambridge, United
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Kintish, K. 2007a. Making dirty coal plants
cleaner. Science 317: 184-186.
Kintish, K. 2007b. Report backs more
projects to sequester CO2 from coal. Science
315:1481.
Lal, R. 2007. Carbon management in
agricultural soils. Mitigation and Adaptation
Strategies for Global Change 12: 303-322.
Abstract: World soils have been a major source
of enrichment of atmospheric concentration of
CO2 ever since the dawn of settled agriculture,
about 10,000 years ago. Historic emission of soil
C is estimated at 78 ± 12 Pg out of the total
terrestrial emission of 136 ± 55 Pg, and postindustrial fossil fuel emission of 270 ± 30 Pg.
Most soils in agricultural ecosystems have lost
50 to 75% of their antecedent soil C pool, with
the magnitude of loss ranging from 30 to 60 Mg
C/ha. The depletion of soil organic carbon (SOC)
pool is exacerbated by soil drainage, plowing,
removal of crop residue, biomass burning,
subsistence or low-input agriculture, and soil
degradation by erosion and other processes. The
magnitude of soil C depletion is high in coarsetextured soils (e.g., sandy texture, excessive
internal drainage, low activity clays and poor
aggregation), prone to soil erosion and other
degradative processes. Thus, most agricultural
soils contain soil C pool below their ecological
potential. Adoption of recommend management
practices (e.g., no-till farming with crop residue
mulch, incorporation of forages in the rotation
cycle, maintaining a positive nutrient balance,
use of manure and other biosolids), conversion
of agriculturally marginal soils to a perennial
land use, and restoration of degraded soils and
wetlands can enhance the SOC pool. Cultivation
of peatlands and harvesting of peatland moss
must be strongly discouraged, and restoration of
degraded soils and ecosystems encouraged
especially in developing countries. The rate of
SOC sequestration is 300 to 500 Kg C/ha/yr
under intensive agricultural practices, and 0.8 to
1.0 Mg/ha/yr through restoration of wetlands. In
soils with severe depletion of SOC pool, the rate
of SOC sequestration with adoption of
restorative measures which add a considerable
amount of biomass to the soil, and irrigated
farming may be 1.0 to 1.5 Mg/ha/yr. Principal
mechanisms of soil C sequestration include
aggregation, high humification rate of biosolids
applied to soil, deep transfer into the sub-soil
horizons, formation of secondary carbonates and
leaching of bicarbonates into the ground water.
The rate of formation of secondary carbonates
may be 10 to 15 Kg/ha/yr, and the rate of
leaching of bicarbonates with good quality
irrigation water may be 0.25 to 1.0 Mg C/ha/yr.
The global potential of soil C sequestration is 0.6
to 1.2 Pg C/yr which can off-set about 15% of
the fossil fuel emissions.
Myhre, G., and A. Myhre. 2003.
Uncertainties in radiative forcing due to surface
albedo changes caused by land-use changes.
Journal of Climate 16: 1511–1524.
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Pacala, S., and R. Socolow. 2004.
Stabilization wedges: solving the climate
problem for the next 50 years with current
technologies. Science 305: 968-972.
Abstract: Humanity already possesses the
fundamental scientific, technical, and industrial
know-how to solve the carbon and climate
problem for the next half-century. A portfolio of
technologies now exists to meet the world's
energy needs over the next 50 years and limit
atmospheric CO2 to a trajectory that avoids a
doubling of the preindustrial concentration.
Every element in this portfolio has passed
beyond the laboratory bench and demonstration
project; many are already implemented
somewhere at full industrial scale. Although no
element is a credible candidate for doing the
entire job (or even half the job) by itself, the
portfolio as a whole is large enough that not
every element has to be used.
Rau, G.H., and K. Caldiera. 2007. Coal’s
Future: clearing the air. Science 316: 691.
Raymond, P.A., and J.J. Cole. 2003
Increase in the Export of Alkalinity from North
America's Largest River. Science 301: 88-91.
Righelato, R., and D.V. Spracklen. 2007.
Carbon mitigation by biofuels of by saving and
restoring forests? Science 317: 902.
Rosenzweig, C., and F.N. Tubiello. 2007.
Adaptation and mitigation strategies in
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Mitigation and Adaptation Strategies for Global
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Sheppard, M.C., and R.H. Socolow. 2007.
Sustaining fossil fuel use in a carbon-constrained
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ipc/www/idb/worldpopinfo.html. U.S. Census
Bureau, Washington, DC.
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