GREENHOUSE EFFECT,
CARBON CYCLE & RISING
TEMPERATURES
THE QUESTION OF THE CENTURY:
WHY THE GLOBAL TEMPERATURE
RISE?
•Natural?
OR
• Humancaused?
This issue has been debated hotly for years
THE ANSWER……




In 2007, the world’s climate scientists combined to
produce the single most comprehensive and
authoritative research summary on climate change:
The Fourth Assessment Report of the
Intergovernmental Panel on Climate Change (IPCC)
The IPCC report summarized all scientific data on
climate change, future predictions, and possible impacts
and concluded:

“….global warming is very likely manmade (or anthropogenic).”
SUMMARY
Virtually all climate researchers agree that global
climate is changing
 Virtually all climate researchers agree that human
fossil fuel use plays a large role in driving climate
change.
 In order to understand how fossil fuel is causing
climate change, one must understand:


1.
The Greenhouse Effect
2.
Greenhouse Gasses
3.
Disruption of the Carbon Cycle
Let’s take a closer look….
THE GREENHOUSE EFFECT, CARBON CYCLE
& RISING TEMPERATURES
I.
The Greenhouse Effect
A.
B.
II.
Carbon Cycle
A.
B.
III.
Carbon sources & sinks
Long-term records of carbon dioxide
Rising Temperatures
A.
B.
IV.
Earth’s Energy Balance
Greenhouse Gases
Recent & Long-term Temperatures Trends
Datasets & Proxy Records
Modeling Climate Change
A.
B.
C.
The Earth As a System
Forward & Negative Feedback Loops
A closer look at the role of water vapor
PART I:
GREENHOUSE EFFECT
THE GREENHOUSE EFFECT--OVERVIEW
Definition
Radiation: energy
that is
propagated in the
form of
electromagnetic
waves.
Vocabulary in the graphic:
• 1) Incoming solar energy is called solar radiation
• 2) Solar radiation warms the earth
• 3) The warmed earth radiates heat. However, this is not called ‘heat’, but rather in
scientific terms it is energy. The correct term is infrared radiation
• 4) The atmospheric ‘blanket’ is gas molecules in the atmosphere.
EARTH’S ENERGY BALANCE
incoming
radiation
Solar energy reaches the Earth’s surface
The earth surface absorbs the energy and warms up
EARTH’S ENERGY BALANCE
Incoming
solar
radiation
greenhouse
gases
infrared radiation (IR)
The warm earth surface radiates infrared radiation (IR
Greenhouse gases absorb IR leaving the surface
EARTH’S ENERGY BALANCE
Incoming
solar
radiation
greenhouse
gases
infrared radiation
Gases are energized, then emit more radiation (IR)
EARTH’S ENERGY BALANCE
Incoming
solar
radiation
greenhouse
gases
infrared radiation
Some of this IR returns to the earth surface, warming
it further
EARTH’S ENERGY BALANCE
Incoming
solar
radiation
greenhouse
gases
infrared radiation
This process is what we call the GREENHOUSE EFFECT!
GREENHOUSE GASES

Obviously, those ‘greenhouse gases’ play an
important role in trapping the infrared radiation.
What are they?
In order of abundance:
1.Water vapor (H2O)
2.Carbon Dioxide (CO2)
3.Methane (CH4)
4.Nitrous Oxide (N2O )
5.Ozone (O3)
GREENHOUSE GASES
1. The atmosphere is a layer of gaseous materials,
some of which interact with infrared radiation and
absorb and re-radiate that energy
 2. The greenhouse gases have been in the
atmosphere a long time (billions of years). They
maintain the planet’s global temperature in a range
that allowed our life forms to evolve
 3. If they have always been there, and the
‘greenhouse effect’ is natural, then why do we now
hear about it causing the earth’s temperature to
rise?
 4. Answer?
 The amount of greenhouse gases in the
atmosphere is increasing

GREENHOUSE GASES
Greenhouse Gas Increases in the last 100 years
Greenhouse
Gas
Concentration
1800s
Concentration
1990s
Percent
Increase
Anthropogenic
Sources
CO2
280 ppm
360 ppm
29%
CH4
0.95 ppm
1.7 ppm
79%
CFCs
0
0.7 ppb
----
burning fossil
fuels;
deforestation
agriculture; fuel
leakage
refrigerants
N2O
250 ppb
310 ppb
24%
O3
15 ppb
20-30 ppb
33-100%
agriculture;
combustion
urban pollution
GREENHOUSE GASES
Things to Know


The biggest problem is
increasing CO2, carbon
dioxide.
CH4, Methane, is also
increasing and interacts
with IR and has more
“global warming potential”
than CO2
Water vapor



Water in the atmosphere is
in the gas or vapor form.
(In fact if it becomes liquid
form then it falls out of the
atmosphere.. as..?)
Water vapor also traps
heat and is a GG
But - It’s a complicated
story because vapor as
clouds may cool the earth
Long-term Records of C02
Long-term proxy
records show
that the earth’s
temperature
varied
considerably
over the past
150,000 years
NOTICE!:
1) THE CO2-TEMP CORRELATION. IS IT CAUSE-EFFECT?
2) THE RATE AND DEGREE OF CHANGE OF C02 IN THE PAST 200
YEARS. HOW DOES IT COMPARE TO THE PAST 150,000 YEARS?
THE GREENHOUSE EFFECT:
STUDENT HANDOUT #1
PART II:
CARBON CYCLE
INTRODUCTION TO CARBON CYCLING
This module will introduce you to the global carbon cycle.
 An important idea in this section is that the atmosphere, oceans
and land are all connected through the cycling of elements such
as carbon.
 The earth is one system and everything that happens on our
planet becomes part of the interactions between air, water, land
and life.
 The global carbon cycle has been disrupted and is causing climate
change.

THE CARBON CYCLE: WHAT IS CARBON?
Carbon is an element. ‘C’
 It can bond with oxygen and form Carbon Dioxide
or ‘CO2’. CO2 is found in the atmosphere (and the
air around us).
 C can dissolve in water and bond with other
molecules to form liquid compounds such as
carbonic acid.
 C also bonds with other carbon molecules to form
numerous compounds, for example sugars and
carbohydrates, that are a part of all living
organisms.

THE CARBON CYCLE: WHAT IS CARBON?

Two important points:

1) Carbon can be in the form of a gas (in the atmosphere), a liquid
(in oceans) and a solid (in all living things on land, and in some
rock formations).

2) Carbon forms the backbone of the biology of all life on earth.
All plants and animals on land and in the water use carbon as a
basic building block. To date, no life has been observed that is not
carbon-based.
THE CARBON CYCLE: WHAT IS A CYCLE?

The carbon cycle: what does ‘cycle’ mean?

A cycle has no distinct beginning and end
This is a line.
This is a linear process.

This is a cycle.
It is a circular pathway and has no
clear start and finish.
Carbon is a part of the biogeochemical cycling of elements
that interconnects the land, the air, and the waters
‘Bio’ – living or biotic elements
 ‘Geo’ – earth, geology, soils
 ‘Chemical’ – molecules and compounds

The Carbon Cycle: What is a cycle? When you
think of the earth, think of it as a system.
The earth is a system in which materials, suchas
carbon and water, continuously cycle. Keep this
image in mind.
Or, do you know another image that means ’interconnectedness’ to you?
THE CARBON CYCLE
Carbon molecules cycle, meaning that they move
through the land, the air, and the water.
 Here is one example of a ‘trip’ that a carbon molecule
may take:



A tree in a forest is made of carbon (C ). When it burns, some C is
converted/released as carbon dioxide (CO2). This CO2 goes into the
atmosphere and travels through the air currents. A corn plant then
takes up that CO2 in photosynthesis and uses it to make
carbohydrates that go into a corn kernel. The corn is harvested and
made into breakfast cereal that you eat - and that C is now a part
of you.
Carbon illustrates the interconnection of all organisms on earth,
and their connection to the atmosphere and waters of the planet.
CARBON CYCLING ON THE LAND:
PLANTS AND SOIL


Carbon moves in and
out of plants and soil as
CO2
Photosynthesis in plant
leaves



Takes in CO2
CO2 is ‘food’ for plants
Respiration in plant
leaves, roots, and soil


Releases CO2
CO2 is produced in
metabolism and the extra
is released
Soils have microbes that
decompose plant material when it
falls to the ground. Microbes are
alive and they respire as part of
their metabolism.
CARBON CYCLING IN PLANTS AND SOIL
A closer look at photosynthesis..
CARBON CYCLING ON THE LAND:
PLANTS AND SOIL
Just to be sure you understand this…..
 Plants run the carbon cycle on land.
Respiration
Photosynthesis
CO2 + O2

CO2 +
Water +
Sunlight
Some CO2 is lost
from the plant in
the process of
metabolism
Make C-rich
sugars and
carbohydrate
s to feed
themselves
and grow
Grow and
store C in
the plant
Die,
decay and
store C in
soil
CAN YOU DRAW THE PLANT AND SOIL C CYCLE ?


For practice - draw a simple diagram of the carbon cycle in a forest.
Where is CO2 moving into and out of the atmosphere? Draw arrows
showing how CO2 cycles between the atmosphere, plants, and soil.
Leaves take in CO2 from the air and use it for photosynthesis
 All plant parts – leaves, wood, even roots – respire CO2 back out to
the air
 Also, as plants decay, soil microbes respire CO2 into the air


Where is carbon stored? Label where Carbon is stored as plant
material or in soils.
Carbon is in wood, leaves, flowers, all plant parts
 Carbon is belowground in the roots
 Carbon is in the soil as organic matter – the decaying plant parts

CARBON CYCLING IN THE OCEAN



The oceans play a vital
role in the global
carbon cycle
CO2 mixes in the ocean
and cycles between the
ocean surface and the
atmosphere
CO2 is stored in the
ocean waters and in
sediments of the deep
ocean floor
CO2 mixing
Dissolved carbon
in ocean water
Calcium carbonate
in ocean floor
Carbon is stored in the ocean as it
dissolves in sea water, and it is stored
when it forms sedimentary rock in the
deep ocean floor
CAN YOU DRAW THE GLOBAL C CYCLE
FOR LAND AND OCEANS ?





Go back to the simple drawing you did of the carbon cycle on land in a forest.
Now add carbon cycling of the ocean to the drawing.
Where is CO2 moving into and out of the atmosphere? ? Draw arrows showing
how CO2 cycles between the atmosphere, plants, and soil. Draw arrows showing
how CO2 cycles between the atmosphere and ocean.
Where is carbon stored? Label where carbon is stored as plant material or in
soils. Also label the carbon stored in seawater and in the ocean floor.
IMPORTANT: The movement of C in and out of the atmosphere as CO2 is called
a ‘flux’. Fluxes are shown by arrows in a diagram. When C is stored it is just
labeled as carbon or else it is shown in a box in a diagram.
Student Handout #2 – graphic of the carbon cycle. Compare your drawing and
check to see if your drawing has the correct ideas.
THE GLOBAL CARBON CYCLE
Which exchanges of CO2
with the atmosphere
have always been a
part of the global
carbon cycling system
and are in your
drawing?
Which are not in your
drawing? These are
due to human
activities!
(Student Handout #2 here –
“Intro to C cycling” for use in
class with next 3 slides)
Terrestrial Oceans
DISRUPTION OF THE NATURAL
CARBON CYCLE

GLOBAL
The two human activities that add the most CO2 to the
atmosphere are:
Extracting the very old,
buried C that is oil, coal
and natural gas.
Burning it for energy
releases CO2.
Land clearing and
deforestation of tropical
forests. The slash piles are
burned and release CO2
THE GLOBAL CARBON CYCLE






Ok – one more
time: Where is
carbon?
1)Atmosphere
2) Ocean
3) Land
And…
buried deep in the
earth as decayed
plant material
from long ago....
Fossil Fuels such
as coal, oil and
gas
DO YOU GET THE CONCEPT?

Take a minute and answer these questions:

What is a possible connection between a car driving down the
road and the amount of CO2 in the atmosphere. Between a
tree growing in a forest and the amount of CO2 in the
atmosphere?
CO2
CO
2
CO2
CARBON CYCLING: IMPORTANT!!!
THE AMOUNT OF CO2 IN THE ATMOSPHERE IS
INCREASING


Since the 1970s scientists
have been measuring the
concentration of CO2 in
the atmosphere at a tower
in Mauna Loa, Hawaii.
Concentration is
measured in ppm (parts
per million).
CO2 has increased from
an average of about 325
ppm in 1970 to an average
of about 385 ppm in 2008
(Student Handout #3
here – “Increasing
atmospheric CO2” - for
use in class with next 2
slides)
CARBON CYCLING: THE AMOUNT OF CO2 IN
THE ATMOSPHERE IS INCREASING



How can scientists know what the atmospheric concentration of CO2 was
before they had the Mauna Loa tower?. They can estimate CO2 using ice
cores pulled from ice sheets in Antarctica and Greenland.
This is called a ‘proxy record’
Measurements from Antarctic ice cores show that atmospheric CO2
concentrations stayed between about 200 and 290 ppm during the
preceding 400,000 years.
Long-term records of temperature & C02
Long-term proxy
records show
that the earth’s
temperature
varied
considerably
over the past
150,000 years
NOTICE:
1) THE CO2-TEMP CORRELATION. IS IT CAUSE-EFFECT?
2) THE RATE AND DEGREE OF CHANGE OF C02 IN THE PAST 200
YEARS. HOW DOES IT COMPARE TO THE PAST 150,000 YEARS?
2000-2006
fossil fuel
emissions
Source
7.6
deforestation
Sink
CO2 flux (Pg C y-1)
Perturbation of Global Carbon Budget (1850-2006)
atmospheric
CO2
land
ocean
Time (y)
Le Quéré, unpublished; Canadell et al. 2007, PNAS
1.5
4.1
2.8
2.2
Source: Anthropogenic C Emissions: Land Use
Change
Carbon Emissions from Tropical Deforestation
2000-2006
1.5 Pg C y-1
1.60
Africa
1.40
Latin America
1.20
S. & SE Asia
(16% total emissions)
SUM
1.00
0.80
0.60
0.40
Houghton, unpublished
2000
1990
1980
1970
1960
1950
1940
1930
1920
1910
1900
1890
1880
1870
0.00
1860
0.20
1850
Pg C yr-1
1.80
Source: Anthropogenic C Emissions: Fossil Fuel
2006 Fossil Fuel: 8.4 Pg C
Atmoapheric [CO2] (ppmv)
Fossil Fuel Emission (GtC/y)
[2006-Total Anthrop. Emissions:8.4+1.5 = 9.9 Pg]
9
Emissions
8
7
6
5
4
3
2
1
0
1850
4001850
380
360
340
320
1870
1870
1890
1890
1910
1910
1930
1930
1950
1950
1970
1970
1990
1990
2010
2010
[CO2]
1990 - 1999: 1.3% y-1
2000 - 2006: 3.3% y-1
300
Raupach et al. 2007, PNAS; Canadell et al 2007, PNAS
280
2 ppm/year
Partition of Anthropogenic Carbon Emissions into Sinks
[2000-2006]
45% of all CO2 emissions accumulated in the atmosphere
Atmosphere
The Airborne Fraction
The fraction of the annual
anthropogenic emissions that
remains in the atmosphere
55% were removed by natural sinks
Ocean removes _ 24%
Land removes _ 30%
Canadell et al. 2007, PNAS
Carbon Intensity and the Global Economy
Carbon intensity
(KgC/US$)
Photo: CSIRO
Kg Carbon Emitted
to Produce 1 $ of Wealth
1960
1970
Canadell et al. 2007, PNAS
1980
1990
2000
Drivers of Anthropogenic Emissions
Population growth & Carbon Intensity
1.5
Factor (relative to 1990)
1.4
1.5
World
1.4
1.3
1.3
1.2
1.2
1.1
1.1
1
1
0.9
0.9
0.8
FEmissions
(emissions)
PPopulation
(population)
= per capita GDP
gWealth
= G/P
intensity of GDP
hCarbon
= F/G
0.7
0.6
0.5
1980
1985
1990
Raupach et al 2007, PNAS
1995
2000
0.8
0.7
0.6
0.5
2005
1980
The Efficiency of Natural Sinks: Land and Ocean Fractions
Land
Ocean
Canadell et al. 2007, PNAS
Credit: N.Metzl, August 2000, oceanographic cruise OISO-5
Causes of the Declined in the Efficiency of the Ocean Sink

Part of the decline is attributed to up
to a 30% decrease in the efficiency of
the Southern Ocean sink over the
last 20 years.

This sink removes annually 0.7 Pg of
anthropogenic carbon.

The decline is attributed to the
strengthening of the winds around
Antarctica which enhances
ventilation of natural carbon-rich
deep waters.

The strengthening of the winds is
attributed to global warming and the
ozone hole.
Le Quéré et al. 2007, Science
PART III:
RISING TEMPERATURES
Recent & Long-term Temperature Trends
Datasets & Proxy Records
RISING TEMPERATURE
The earth’s temperature has increased in the
last 200 years - this is a scientific fact.
 The temperature increase of the last 200 years
has been measured.
 Temperature change is not the same all over the
world. In fact, some places are the same or
cooler, although most places are warmer. It’s
the global average that’s increased.

Here is the important point:
The globally averaged earth surface temperature
has increased, it has increased in the last 200
years, and the increase was measured by
weather instruments.
WHAT IS KNOWN—THE EARTH IS WARMING
“Warming of the climate
system is unequivocal,
as is now evident from
observations of
increases in global
average air and ocean
temperatures,
widespread melting of
snow and ice and
rising global average
sea level.”
IPCC report 2007, synthesis, p. 30
IPCC 2007 REPORT
Eleven of the last twelve years (1995–2006) rank
among the 12 warmest years in the instrumental
record of global surface temperature (since 1850).
 The linear warming trend over the last 50 years
(0.13°C [0.10°C to 0.16°C] per decade) is nearly
twice that for the last 100 years.
 The total temperature increase from 1850–1899
to 2001–2005 is 0.76°C [0.57°C to 0.95°C].


Urban heat island effects are real but local, and have a negligible influence (less
than 0.006°C per decade over land and zero over the oceans) on these values.
RISING TEMPERATURE
Student Handout #4: go over handout of this data
RISING TEMPERATURE
What about longer than
200 years?
Temperature
Increase
200 years
 Measured
 Scientific
Fact

What about the last 2000 years?
Or 200,000 years?
 How do we determine this?
 Scientists use “proxy methods” to
estimate temperature and carbon
dioxide concentrations

PROXY RECORDS: ICE CORES



Ice caps and glaciers
accumulated over thousands
or millions of years.
They contain bubbles of gas
preserved from the time
when each layer formed.
Scientists drill cores and
analyze the gas bubbles in
each layer to see what the
atmosphere was like at that
time.
Figure 12.5
PROXY RECORDS: POLLEN ANALYSIS


Scientists also drill
cores into the
sediments of ancient
lake beds.
By identifying types of
pollen grains in each
layer, they can tell
what types of plants
were growing there at
the time.
PROXY RECORDS: PACKRAT MIDDENS
White-throated woodrat
A giant 28,000+
year-old packrat
midden under an
overhang at Capitol
Reef National Park,
Utah. Orange
notebook is 7" X 4".
Fossil packrat (or woodrat) middens provide
information on past environments because they
are a rich source of debris collected by packrats
in the past.
Photo by Ken Cole
The packrat often urinates on its garbage pile, marking its territory. When this
urine crystallizes, it acts as a glue holding the entire garbage pile together. Fossil
debris held within the midden becomes mummified, preserving it indefinitely.
Note: Photos & text on this slide are from:
http://cpluhna.nau.edu/Tools/packrat_middens.htm

For information on other tools used to reconstruct past
climate, see http://cpluhna.nau.edu/Tools/tools.htm
CLIMATE CHANGE AND THE IPCC REPORT
Proxy indicators of temperature (from pollen, ice cores,
etc.) were reviewed to establish ancient temperatures.
 These data (BLUE) overlapped with the direct temperature
measurements (RED). (Gray shows statistical uncertainty.)

PART IV:
MODELING CLIMATE CHANGE
Earth as a System
Forward and Negative Feedback Loops
STUDYING CLIMATE CHANGE: MODELING
 To
predict what will happen to climate in the
future, scientists use climate models:
 Computer
simulations that use known
behavior of past climate to analyze how climate
should behave as variables are changed.
 Coupled
general circulation models
(CGCMs) are models that combine, or couple,
the effects of both atmosphere and ocean.
EARTH’S ENVIRONMENTAL SYSTEMS
Our planet consists of many complex, large-scale,
interacting systems.
System
= a network of relationships among a group of
parts, elements, or components that interact with and
influence one another through the exchange of energy,
matter, and/or information
Feedback
loop = a circular process whereby a
system’s output serves as input to that same system.
FEEDBACK LOOPS: NEGATIVE FEEDBACK
In
a negative feedback loop, output acts as input that
moves the system in the opposite direction.
This compensation stabilizes the system
NEGATIVE FEEDBACK LOOPS
1. Increase oceanic
algae = more
absorption
2. Increase plant
growth = more
absorption
3. More polar snow
= more
reflectance
4. More clouds =
more reflectance
FEEDBACK LOOPS: POSITIVE FEEDBACK
In
a positive
feedback loop,
output acts as
input that moves
the system
further in the
same direction.
This
magnification of
effects
destabilizes the
system.
POSITIVE FEEDBACK LOOPS
5. More clouds =
more greenhouse
effect
6. Melting
permafrost =
more methane
7. Less snow/ice =
less reflectance
8. More warmth =
more air
conditioning
GREENHOUSE GASES
WATER VAPOR FEEDBACK
Surface
temperature
Atmospheric
H2O
(+)
Greenhouse
effect
Positive feedback loop
As the earth warms, there is an increase in
water vapor, increase in warming, increase in
water vapor, increase in warming …
GREENHOUSE GASES
WHAT ABOUT CLOUDS?
Most scientists predict that cloudiness will
increase as the climate warms. But, what
do more clouds do to the earth’s
temperature?
1. Increase temperature because water
vapor traps heat? A positive feedback
2. Decrease temperature by shielding the
earth from incoming solar radiation. A
negative feedback.
3. Hard to know. Plus – depends on the
WHAT ABOUT CLOUDS?
Less reflection
10 km
IR
Thin, High clouds could warm
the earth’s temperature by
trapping IR
Cirrus clouds
(Thin)
More reflection
Altitude
Cumulus/stratus clouds
(Thicker)
Fat, low clouds could cool
the earths temperature by
blocking incoming radiation
References

Canadell JG, Corinne Le Quéré, Michael R. Raupach, Christopher B. Field, Erik T. Buitehuis,
Philippe Ciais, Thomas J. Conway, NP Gillett, RA Houghton, Gregg Marland (2007) PNAS.

Canadell JG, Pataki D, Gifford R, Houghton RA, Lou Y, Raupach MR, Smith P, Steffen W
(2007) in Terrestrial Ecosystems in a Changing World, eds Canadell JG, Pataki D, Pitelka L
(IGBP Series. Springer-Verlag, Berlin Heidelberg), pp 59-78.

Raupach MR, Marland G, Ciais P, Le Quéré C, Canadell JG, Klepper G, Field CB, PNAS
(2007) 104: 10288-10293.

Le Quéré C, Rödenbeck C, Buitenhuis ET, Thomas J, Conway TJ, Langenfelds R, Gomez A,
Labuschagne C, Ramonet M, Nakazawa T, Metzl N, et al. (2007) Science 316:1735-1738.