Alan Robock

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Global Warming
Alan Robock Department of Environmental
Sciences Rutgers University, New Brunswick, New
Jersey USA
robock_at_envsci.rutgers.edu
http//envsci.rutgers.edu/robock
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http//data.giss.nasa.gov/gistemp/2007/Fig1_2007an
nual.pdf
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Global Warming Fundamental Questions
1. How will climate change in the future? 2. How
will climate change affect us? 3. What should we
do about it?
Considerable warming, glacier retreat, more
precipitation and extremes, extinctions, stronger
hurricanes, and sea level rise Some winners but
more losers, including water, tropical
agriculture, national security Mitigation now
(reduce emissions, efficiency) is cheaper than
waiting, study impacts, adapt
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Global Warming Fundamental Questions
1. How will climate change in the future? 2.
How will climate change affect us? 3. What
should we do about it?
Intergovernmental Panel on Climate Change (IPCC)
Working Group I (WG I) IPCC WG II IPCC WG III
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Intergovernmental Panel on Climate Change
(IPCC) Established in 1988 jointly by the World
Meteorological Organization and the UN
Environment Programme 3000 scientists from more
than 150 nations Winner of 2007 Nobel Peace Prize
First Assessment Report (FAR), 1990 Second
Assessment Report (SAR), 1996 Third Assessment
Report (TAR), 2001 Fourth Assessment Report
(4AR), 2007
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In this Summary for Policymakers, the following
terms have been used to indicate the assessed
likelihood, using expert judgment, of an outcome
or a result Virtually certain gt 99
probability of occurrence Extremely likely gt
95 Very likely gt 90 Likely gt 66 More likely
than not gt 50 Unlikely lt 33, Very unlikely lt
10 Extremely unlikely lt 5
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The unequivocal detection of the enhanced
greenhouse effectfrom observations is not likely
for a decade or more. Climate Change The IPCC
Scientific Assessment (1990)
The balance of evidence suggests a discernible
human influence on global climate. Climate
Change 1995 The Second Assessment of the
Intergovernmental Panel on Climate Change (IPCC)
Most of the observed warming over the last 50
years is likely to have been due to the increase
in greenhouse gas concentrations. Climate Change
2000 The Third Assessment Report of the IPCC
Most of the observed increase in globally
averaged temperaturessince the mid-20th century
is very likely due to theobserved increase in
anthropogenic greenhouse gas concentrations. Clim
ate Change 2007 The Fourth Assessment Report of
the IPCC
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The unequivocal detection of the enhanced
greenhouse effectfrom observations is not likely
for a decade or more. Climate Change The IPCC
Scientific Assessment (1990)
The balance of evidence suggests a discernible
human influence on global climate. Climate
Change 1995 The Second Assessment of the
Intergovernmental Panel on Climate Change (IPCC)
Most of the observed warming over the last 50
years is likely to have been due to the increase
in greenhouse gas concentrations. Climate Change
2000 The Third Assessment Report of the IPCC
Most of the observed increase in globally
averaged temperaturessince the mid-20th century
is very likely due to theobserved increase in
anthropogenic greenhouse gas concentrations. Clim
ate Change 2007 The Fourth Assessment Report of
the IPCC
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But, what is a greenhouse gas anyway?

• Nitrogen (N2), oxygen (O2), and argon (Ar) make
  up for 99 of the atmosphere, but are not
  greenhouse gases.
• Water vapor (H2O), carbon dioxide (CO2), methane
  (CH4), ozone (O3), and nitrous oxide (N2O) are
  greenhouse gases.
• A greenhouse gas absorbs infrared radiation,
  which creates molecular vibration and bending.
• Collisions transfer energy to heat the
  surrounding gas.

http//www.ucar.edu/learn/1_3_1.htm
Modified from slide by R. César Izaurralde,
University of Maryland
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IPCC AR4 Simulations (from 13 different climate
models from around the world)
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IPCC AR4 Simulations (from 13 different climate
models from around the world)
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Observations
As simulated with all forcings
As simulated with only natural forcings
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CCSM Climate Forecasts
(C)
(C)
Produced by Gary Strand, NCAR
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Increases in the amount of precipitation are
very likely in high-latitudes, while decreases
are likely in most subtropical land regions,
continuing observed patterns in recent trends.
Relative changes in precipitation () for the
period 20902099, relative to 19801999.
Stippled areas are where more than 90 of the
models agree in the sign of the change.
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Climate Change Fundamental Questions
3. What should we do about it?
This is a political decision to be made by
society and individuals, and is based on
values. Cannot be answered directly by science,
but mitigation and adaptation need to be informed
by scientific results, for example - the
response to different mitigation choices -
scenarios for implementation of mitigation and
adaptation, such as wind climate for wind
generators, or future climate for agriculture -
assess carbon offset schemes
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The United NationsFramework Convention On
Climate Change 1992 Signed by 194 countries and
ratified by 188(as of February 26, 2004) Signed
and ratified in 1992 by the United States The
ultimate objective of this Convention ... is to
achieve ... stabilization of greenhouse gas
concentrations in the atmosphere at a level that
would prevent dangerous anthropogenic
interference with the climate system.
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How do you define Dangerous Change? Exterminati
on of Animal Plant Species 1. Extinction of
Polar and Alpine Species 2. Unsustainable
Migration Rates Ice Sheet Disintegration Global
Sea Level Rise Regional Climate Change 1. More
Strong Hurricanes 2. Droughts/Floods 3. Threats
to Water and Food Supply A Warming gt1C Risks a
Different Planet.
Partly from Jim Hansen, 11/21/06
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To avoid warming gt1C - Maximum CO2 450 ppm -
Slightly larger if non-CO2 forcings (e.g.,
methane, black carbon particles) decrease Gas
and Oil Use Most of 450 ppm Limit - Gas and oil
must be stretched via efficiency - Coal and
unconventional fossil fuels must be phased out or
capture CO2 - Future power plants must be
zero-CO2 - Vehicles eventually must be zero-CO2
Partly from Jim Hansen, 11/21/06
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What the you can do immediately
- Support legislation that will help solve the
problem, both in New Jersey and in Congress. -
Vote for legislators and a President who will
help solve the problem. - Install solar cells,
with New Jersey helping to pay the bill. - Use
less energy Less driving (telecommute, bike,
train, bus) Smaller car/hybrid Insulate your
house Cooler house in winter, warmer in
summer Buy local products Compact fluorescent
bulbs Less meat (energy, methane) Recycle Biodiese
l
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The New York Times, Oct. 8, 2006
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Explanation of gas price 1.20 fuel,
refining 0.27 distribution 0.50 profit 0.25 sta
te highways 0.10 federal highways 4.05 military
0.69 local air pollution 0.57 climate change
0.00 marketing 7.63 Total
Gallons
13.563
Price per gallon
7.639
Total
103.61
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Copulos (2006)
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The words of the prophets are written on the
subway walls Sounds of Silence (Simon and
Garfunkel, 1966)
Very Likely
Photograph by Warren Washington