What Does Science Say
About Climate Change?
Prof. Bill Moomaw
Fletcher School, Tufts University
November 2004
The Earth’s Climate System

Light from the Sun is absorbed by land and
water, and is converted to heat.
 Some heat is emitted back into space as radiant
heat, just as heat is radiated from hot pavement
on a July day.
 Some of this radiant heat is absorbed by water
vapor and clouds, carbon dioxide, methane,
nitrous oxide and other trace atmospheric
gases.
 These gases act like the glass windows in a car
creating the “hot car effect.”
“Hot Car” Effect and Climate Change
Natural
Enhanced
Brief History of Climate
Change Science
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1827 Fourier hypothesizes greenhouse effect
1860 Tyndal identifies CO2 and water vapor as
heat trapping gases
1896 Arrenhius calculates earth warming from
gases and predicts future warming from
doubling and quadrupling CO2
1930 Calandar shows correlation of temperature
and CO2
1958 Keeling begins direct measurement of CO2
in atmosphere
1980 to 2004 evidence accumulates
The one constant of climate
has been change by natural
forces.
What is new is that human
activities are altering the
composition and size of the
atmosphere, the face of the
land, and the climate system.
What natural forces affect the
climate system?
 Natural
fluctuations in the sun’s intensity
 The complex motion of the earth around
the sun
 Volcanic eruptions
 Changes in ocean currents
 Shorter-term cycles like El Nino
What natural forces affect the
climate system?
 Natural
fluctuations in the sun’s intensity
 The complex motion of the earth around
the sun
 Volcanic eruptions
 Changes in ocean currents
 Shorter-term cycles like El Nino
What human activities are
affecting climate?
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Carbon dioxide from fossil fuels release about 6
billion tons of carbon each year to the
atmosphere
Atmospheric carbon dioxide concentrations
have increased by nearly 32%
Methane from agriculture, livestock, landfills and
industry have increased by 133%
Nitrous oxide from agriculture and industry has
increased by 15%
Change in land use and land cover release
1 billion tons of carbon plus other gases
What is the evidence for human
caused climate change?
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Direct measurement of changes in atmospheric
composition
Direct measurement of temperatures
Direct measurement of precipitation and other
climate indicators
Direct measurement of shifts in species
Paleoclimate records
Climate model verification
Testing models with other planetary climates:
Venus, Mars and the moons of Jupiter & Saturn
Vostok temperature and CO2
Looking to the Future
 What
will happen to concentrations of
climate altering gases such as carbon
dioxide if we fail to act?
 What will happen to planetary
temperatures if we fail to act?
Major Indicators of Current
Climate Change
 Average
global temperature has risen by
1o F in past 100 years with high latitude
increases of 4o F
 Seasons in the US and Europe have
shifted by one week in past 50 years
 Precipitation patterns are changing
 Species are migrating higher and towards
the poles
level has risen by 6-8” in the past
century and is proceeding at a rate of more
than an inch a decade
 More than 95% of world’s glaciers are
retreating
 Polar sea ice has thinned by more than 40%
in 30 years, and coastal ice shelves are
disintegrating in Antarctica
 Permafrost is warming and melting rapidly,
destroying buildings and roads, and could
disrupt Alaska oil pipeline
 Sea
Upsala Glacier
Patagonia, Argentina
Rhone Glacier Switzerland 1930-2001
Pasterze Glacier Austria
1875-2004
Portage Glacier Alaska
1914-2004
Recent Findings 1

Terrence Joyce of Woods Hole Oceanographic
Institute argues that the observed slowing of the
North Atlantic conveyor could become irreversible if
pushed beyond a threshold by climate related
changes.
 This would cause rapid, major drops in
temperatures in Europe and Eastern North
America.
Link of Climate Change to
Security

:
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In February 2004, the Pentagon published a
report expressing deep concern of the political
and economic destabilization that might
accompany abrupt climate change
http://www.ems.org/climate/pentagon-climate-change.pdf
Fortune magazine highlighted this climate
change - national security link (Fortune February 2004):
http://www

Suddenly, Prof. Wally Broecker’s 1959 doctoral
dissertation idea was news!
Recent Findings 2

Satellite measurements of lower atmosphere
temperatures have been interpreted as rising less
since measurements began in 1979 than land and
sea surface trends.
 This discrepancy has now been resolved.
 Satellite measurements were found to be
measuring part of the cooler stratosphere and not
just the lower troposphere as was thought.
 There is now close agreement with land and sea
temperature trends removing another uncertainty.
QIANG FU, CELESTE M. JOHANSON, STEPHEN G. WARREN & DIAN J.
SEIDEL Nature 429, 55–58 (2004); doi:10.1038/nature02524 (May 6, 2004)
Recent Findings 3
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The sustained drought in the Sahel region of
Africa that began around 1970 has continued
 Not only is total rainfall decreased, but what
does occur comes in intense downbursts
punctuated by drought.
 It has been confirmed that this altered weather
pattern arises from the warming of sea surface
temperature rises in the Indian Ocean.
 “If the sea temperature rise comes from global
warming, then we are in dire straits.”
Alessandra Giannini, Columbia University Science October 13, 2003
Recent Findings 4
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Stratospheric ozone loss may be altering climate
 The altered amount of ozone shifts the wind
patterns around Antarctica with effects that
extend much farther.
 While the Antarctic peninsula has warmed, the
center of the continent has cooled.
 The warming appears to be coming from the
ocean and leading to the spectacular breakup of
state sized ice shelves. Nathan Gillett and David Thompson
Science, 10/10/03

The cooling in the interior appears to be due to
the loss of heat through the ozone hole
Thompson, D. W. J., and S. Solomon,Science, 296, 895-899, 2002
Recent Findings 5
 While
human activities release about 7
billion tonnes of carbon as CO2 each year,
usually half is absorbed by the ocean, by
plants and by soils.
 In 2003, CO2 in the atmosphere increased
substantially above annual growth rates of
the past meaning that less is being
absorbed by terrestrial systems and
oceans.
Recent Finding No. 6
 Antarctic
glaciers are accelerating their
flow into the sea (where they will
accelerate the rise in sea level) since the
collapse of the Larsen ice shelf in 2002
 Some glaciers are found to be thinning at
twice the rate they were in the 1990s
 The loss of the ice shelf is believed to
have occurred because of warmer seas
R.H. Thomas, et al Science, Sept. 23, 2004
Recent Findings 7
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Arctic Climate Impact Assessment released
November 8
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“The Arctic is warming much more rapidly than previously
known, at nearly twice the rate as the rest of the globe..”
In Alaska, Western Canada, and Eastern Russia average
winter temperatures have increased as much as 3-4C (4 to
7F) in the past 50 years, and are projected to rise 4-7C (713F) over the next 100 years.
Greenland ice is melting and contains enough melt water to
eventually raise sea level by about 7 meters (about 23 feet).
So the problem of climate
change is of growing
concern.
What do we do about it?
Problem:
International agreements are
not yet implemented and the
US national government
favors voluntary actions
Solution:
Implementation without Ratification
Options
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Use fossil fuels more efficiently
Move from coal to oil and gas
Extract hydrogen from fossil fuels and store the
carbon
Continue to use fossil fuels but capture and
store CO2 physically and biologically
Develop efficient market instruments to achieve
cost effective energy mix
Utilize other technologies such as nuclear, wind,
solar, biomass and geothermal energy
Business Opportunities

Investment in renewable energy tripled to $18
billion between 1995 and 2002
 The US once dominated wind, solar and
biomass technology, but has fallen behind
countries such as Japan, Germany Denmark
and Brazil
 The IPCC estimates that there is sufficient
technology available to reduce global CO2
emissions by 15% in a decade at zero or net
negative costs
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Fossil fuels dominate the production of electricity
(64%) followed by hydro and nuclear (17%) and
other renewables (2%)
 The growth, however, is in the reverse order
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Wind 25%
Solar 19%
Hydro 2%
Fossil fuels 0-2%
Global Trends
in Energy Use
1992 - 2002
World Electricity
Generation by Type
2000
64%
70%
60%
25.4%
25.0%
19.0%
50%
20.0%
40%
15.0%
30%
17%
17%
10.0%
20%
10%
30.0%
5.0%
2%
0%
Non-hydro
renewables
Hydro
Nuclear
1.9%
1.8% 1.6%
0.6%
0.0%
0.0%
Fossil
Fuels
Wind
Solar
PV
Hydro
Oil
Natural Nuclear
Gas
Coal
Lag Times
Innovative Thinking is Needed to
Address Climate Change
 Now
is the time to act, but it requires
thinking in new, creative ways
 We need to replace talk with action!
 There are opportunities for all sectors of
industry and to applaud and expand the
successful measures of the innovators
 There are opportunities to follow the lead
of innovative cities like Toronto who began
municipal action in 1988
Web sites
 Photos
of glaciers and other evidence of
climate change
http://www.worldviewofglobalwarming.org/i
ndex.html
 Summary and synthesis of scientific
information http://www.ipcc.ch
 Information about Tufts efforts
http://www.tufts.edu/tie/tci