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Carbon & Climate
Atmospheric Carbon Dioxide
CO2 was measured in the
atmosphere starting in the
1950’s at Mauna Loa, Hawaii
CO2 concentrations have
increased:315 ppm to 380 ppm
Greenhouse gases and temperature
Air trapped in ice cores
give a record of past
atmosphere
CO2 was stable for past
1000 years at 280 ppm
Current temperature
increase a sharp change
from past 1000 years
The Current
Atmosphere….
• Clear correlation
between atmospheric
CO2 and temperature
over last 160,000
years
• Current level of CO2
is outside bounds of
natural variability
•Rate of change of
CO2 is also
unprecedented
Source: OSTP
Greenhouse gases
Some solar radiation is
reflected by
atmosphere and Earth
Sun
Atmosphere
Earth
More radiation is absorbed
by Earth and warms it
Infrared radiation (heat)
is released from the
Earth
Some infrared radiation is absorbed
by greenhouse gases warming
Earth and lower atmosphere
Greenhouse gases
Greenhouse warming potential (GWP) -- takes into
account the ability of a gas to absorb infrared radiation,
and the lifetime of the gas in the atmosphere
Gas
carbon dioxide (CO2)
methane (CH4)
[conc]
360 ppm
1745 ppb
GWP
1
23
nitrous oxide (N2O)
CFC-11
314 ppb
268 ppt
296
4600
CFC-13
4 ppt
14000
Greenhouse gases
Note about CFC’s: These gases affect the ozone
layer in the stratosphere
BUT, that is not related to their effect as a
greenhouse gas in the troposphere
Greenhouse gases
Carbon dioxide is the
largest single
contributer to climate
forcing
Carbon dioxide
contributes about half of
total climate forcing from
greenhouse gases
Other important greenhouse gases
include methane, nitrous oxide,
CFCs
whrc.org/carbon/
Carbon dioxide balance
Atmospheric increase
=
Fossil fuel + Land Clearing - Ocean Dissolution Land Uptake
Atmospheric Increase
Fossil Fuel
Land Clearing
Ocean Atmosphere Flux
Land Uptake
3.3
+5.4
+1.7
-1.9
-1.9 Pg?
whrc.org/carbon/
Where’s the Carbon?
Missing sink is large, unmeasured & thought to
be uptake by terrestrial biomes
1. CO2 fertilization of temperate, tropical and
boreal forests?
2. Regrowth of previously deforested areas?
3. Extension of growing season (warmer temp)?
4. Nitrogen fertilization of natural ecosystems?
The Future Atmosphere….
Assuming ‘business-asusual’….
Atmosphere CO2 will be double
that of preindustrial
concentrations by 2050
By 2100 the atmosphere
will be between 600 - 800
ppm
Climate predictions
General circulation models
(GCM) are used to predict
future climate
Driven by physical
processes that involve
transfers of energy and
water
Used with different
greenhouse gas
‘scenarios’ to predict
climate in a future
atmosphere
Climate warming
predicted 1.5 - 6 deg C
High latitudes & and land
surfaces warm most
Washington DC now has
30 days over 90 deg F. Will
have 85 days over 90F
Changes in
Arid zones may
Wet
tropics
may
precipitation are more
become drier
become
wetter
variable globally
Model Prediction Depend on
Future Scenarios
Potential Climate Change Impacts
Health
Weather-related mortality
Infectious diseases
Air-quality respiratory illnesses
Agriculture
Climate Changes
Temperature
Precipitation
Sea Level Rise
Crop yields
Irrigation demands
Forests
Change in forest composition
Shift geographic range of forests
Forest health and productivity
Water Resources
Changes in water supply
Water quality
Increased competition for water
Coastal Areas
Erosion of beaches
Inundation of coastal lands
Costs to protect coastal communities
Species and Natural Areas
Source: EPA
Shift in ecological zones
Loss of habitat and species
Effects of Climate Change
Effects of Climate Change
Sea level rise due to
ice cap melting on
land
Also due to thermal
expansion of water.
Water is less dense
when warmer
Effects of Climate Change
Sea level change in FL
Effects of Climate Change
Low island nations
(Tonga, Marshall
islands) are a few
meters above sea
level
Inhabitants of these
islands may become
the first ecorefugees
as sea level rises
Effects of Climate Change
Forest edge will
move north and be
replaced by
savanna and
woodland
Forest around
Gainesville will
become less dense
with trees and
grasses
South Florida will
become more dense
tropical forest
Effects of Climate Change
Initially, an increase in
crop production in US
due to CO2 fertilization
Canada and other
northern countries
become warmer with
higher crop yield
US, South America,
Africa become warmer,
drier with lower crop
yield
Stabilizing The Future
Atmosphere
Can we change our
trajectory?
Stable atmospheric CO2
depends on changing
emission rate
For all scenarios, final
emission rates must equal
natural uptake (very low)
Stabilizing The Future
Atmosphere
Do we have the political will?
Industrial countries must
decrease emission rates by
5-8 % by 2012 (US not a
participant)
After 2012, no agreement, but
other (developing) countries
will have to decrease
emissions
How to Reduce Emission Rates?
The hydrogen economy
Managing forests as C sinks
Engineering solutions:
deep sea
bedrock