Download MET606-Sp10-Desai - University of Wisconsin–Madison

Is Atmospheric Carbon Dioxide
an Environmental Toxicant?
Prof. Ankur R Desai
Dept.
Atmospheric
& Oceanic
Sciences
Ankur of
Desai,
Atmospheric & Oceanic
Sci., UW-Madison
University
Wisconsin-Madison
CEE 698:
Sustainabilityof
Principles,
Practices, and Paradoxes
Feb 9, 2010
Colloquium in Environmental
Toxicology, 16 March 2010
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Outline
Why CO2 is not a pollutant
The greenhouse gas story
Climate change and ecosystems
Why does that matter for climate policy
and sustainable development?
Why CO2 is a pollutant
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Outline
Why CO2 is not a pollutant
The greenhouse gas story
Climate change and ecosystems
Why does that matter for climate policy
and sustainable development?
Why CO2 is a pollutant
Our Era
• From 1990-2005:
– World Population increased 22% to
~6,500,000,000 people
– Global oil consumption grew 25% to
85,000,000 barrels per day
– Gross World Product (GWP) grew 40% to
$59,380,000,000,000 US dollars
– The number of threatened species increased 40% to
~16,000
• Population doubling times have increased
– 1850-1930, 80 years, 1-2 billion
– 1930-1975, 45 years, 2-4 billion
– 1975-2015, 40 years, 4-8 billion
Source: UCAR
Our Carbon Economy
450
Global Energy Production 1850 to 1994
400
350
Exajoules per Year
300
250
200
150
Nuclear
Hydro
Gas
Oil (feedstock)
Oil
Coal
Wood
CARBON!
100
50
18
50
18
56
18
62
18
68
18
74
18
80
18
86
18
92
18
98
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04
19
10
19
16
19
22
19
28
19
34
19
40
19
46
19
52
19
58
19
64
19
70
19
76
19
82
19
88
19
94
0
Source: IEA
Fossil Fuel Emissions
• Courtesy K. Gurney, Purdue U.
CO2!
Global monthly average CO2 in parts per million (ppm)
Source: NOAA ESRL
Gradients
Measuring Greenhouse Gases
Does a Richer World Pollute Less?
• Source: Nature
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Questions
Why CO2 is not a pollutant
The greenhouse gas story
Climate change and ecosystems
Why does that matter for climate policy
and sustainable development?
Why CO2 is a pollutant
What’s The Big Deal?
IPCC, 4th AR, (2007)
Living in a Greenhouse
Infrared
Solar
Weather
Land/Ocean
Trenberth et al. (2009)
Climate 101
• Earth’s climate is regulated by:
– Solar “shortwave” input
• Sun bathes earth primarily with visible light, which varies very
little year to year on short timescales
– Surface energy budget
• Solar energy is reflected or converted into other forms of
energy (photosynthate, longwave IR, heat, evaporation)
– Atmospheric absorption and emission of surface and
solar energy
• Atmosphere is mostly transparent to solar energy but opaque
to infrared and longer waves
– Fluids that move energy around
• Weather and ocean currents
• Mainly affects spatio-temporal distribution
Living in a Greenhouse
The Atmospheric
Window
Smudging The
Window
A Global Experiment
CO2 (ppm)
385 ppm
(2008)
232 ppm
Ice ages
Years Before Present
Source: Lüthi et al (2008), CDIAC, & Wikimedia Commons
The Big Deal
IPCC AR4 (2007)
Recent Times
Manifestations of the Big Deal
Kucharik and Serbin (2009)
The Future
IPCC AR4 (2007)
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Outline
Why CO2 is not a pollutant
The greenhouse gas story
Climate change and ecosystems
Why does that matter for climate policy
and sustainable development?
Why CO2 is a pollutant
Since 1990
• Global annual CO2 emissions grew 25% to
27,000,000,000 tons of CO2
• CO2 in the atmosphere grew 10% to
385 ppm
• At current rates, CO2 is likely to exceed
500 ppm sometime this century
• But: Rate of atmospheric CO2 increase is about
half the rate of emissions increase. Why?
Where Is The Carbon Going?
Houghton et al. (2007)
Carbon Cycle
Houghton et al. (2007)
Ecosystems Will Respond
A Story
• Expectation:
– Warmer Spring leads to a longer growing
season for plants in high-elevation forests
• Therefore:
– Forest productivity in the Rocky Mountains
should benefit from global warming
That Makes Some Sense
Later springs lead to lower productivity in U.S. northeastern forests
Onset of Spring Anomaly (Days)
• Richardson et al. (2009)
It’s Getting Warmer Out There
• April max monthly temperature trend 1971-2000
Courtesy of R. Behnke, UW; Data source: PRISM group
It’s Getting Warmer Out There
In spring, higher elevations are warming faster than lower
• Courtesy of R. Behnke, UW
Wait, What?
• NEP = Net Ecosystem Production
– Positive = more uptake
Hu et al. (2010)
SURPRISE!
A Tower To Rule Them All
A Flux Tower
• NEE = Net Ecosystem Production
– Positive = More productivity
Courtesy of R. Monson, CU-Boulder
Moisture Matters
Hu et al. (2010)
More Evidence
Soil sfc
Rain
Soil 35 cm
Groundwater
Snowmelt
WATER
SNOW
Hu et al. (2010)
Snow Moisture Matters
• Snow water drives a lot of productivity in
Rocky Mountain subalpine forests
Water
Snow
Hu et al. (2010)
Water
Snow
Water
Snow
Morals
• Warming temperatures are not necessarily
a net positive for ecosystem productivity
• Changes in moisture levels and snow
matter in Western Forests
Montaine subalpine forests
Don’t Forget Bugs!
Raffa et al. (2008)
Pine Beetles
Raffa et al (2008)
Another Warming Feedback
Courtesy of B. Stephens, NCAR
Another Warming Feedback
Mostly alive
Mostly dead
• Declining trend in atmospheric valley CO2?
Courtesy of B. Stephens, NCAR
Rate of Spread
Beetle-Climate Feedback
Spruce beetle
Mountain Pine Beetle
Raffa et al (2008)
Atm. Chem, O3
Precipitation
Temperature
Aerosols
GHGs
NOx
Heat
CO2
Ecosystems
H2O
VOCs
A Small Problem
Friedlingstein et al. (2005)
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Outline
Why CO2 is not a pollutant
The greenhouse gas story
Climate change and ecosystems
Why does that matter for climate policy
and sustainable development?
Why CO2 is a pollutant
• Source: Nature Publishing Group
Multi-Faceted Problem
Does a Richer World Pollute Less?
• Source: Nature
Since 1990
• La Quere et al., 2009
It’s Not Impossible
• Pacala and Socolow, 2004
Will The Carbon Economy Meet Its
Own Demise?
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Outline
Why CO2 is not a pollutant
The greenhouse gas story
Climate change and ecosystems
Why does that matter for climate policy
and sustainable development?
Why CO2 is a pollutant
Why CO2 is a Pollutant
• CO2 in and of itself is relatively benign and
not very reactive
– Lifetime of 100 years!
• It’s the impact on radiative forcing and
ocean acidification that matter
• Ecosystems and society can adapt to slow,
steady, small climate changes
• Less likely with rapid changes and
ecosystem surprises
• There are many co-benefits of fossil fuel
emission reduction with respect to
tradition environmental toxicants!
DISCUSS:
As CO2 is an environmental toxicant, it requires that we
move away from a carbon-energy economy immediately.
- Principle: Anthropogenic climate destabilization is a significant
threat to ecosystems and human civilizations. Sustainable
development must aim to minimize climate damage.
- Practice: Adopt climate mitigation and adaptation strategies in
each sector of the economy that emits greenhouse gases.
- Paradoxes and questions:
- Every sector of the economy depends on a fossil fuel economy, where do we
start?
- Significant uncertainty in climate impacts requires us a adopt a probabilistic
risk-based approach, but what is the right model?
- Local, small changes don’t make a big difference; global action is mired in
politics and bureaucracy
- It’s hard to measure change. What if nothing happens?
- Greenhouse gas mitigation and adaptation is likely to hamper the right of all
people to lift the burden of poverty by economic development. Others argue
that richer people are more likely to improve the environment. What to do?
Acknowledgements
• Desai Ecometeorology Lab (flux.aos.wisc.edu):
• Funding partners: UW Graduate school, NSF,
NOAA, USDA, NASA, DOE
• Many, many collaborators
• Wednesday Nite @ The Lab, UW Alumni Assoc.