Download The Current State of Our Climate

The Current State of Our Climate
Prof. Tim Raymond
Chemical Engineering Dept.
Bucknell University
Focus the Nation – Obstacles to Change
January 31, 2008
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History and Background
• 1800’s - CO2 at 290 ppm; T = 13.6°C
• 1824 - Fourier discovers natural ‘greenhouse
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effect’ of atmosphere
1896 - Swedish scientist Arrhenius predicts
‘greenhouse warming’ from CO2
1960 - CO2 at 315 ppm (up 9% from 1800)
1970’s - Unusual weather creates speculation on
global warming/cooling
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History and Background
• 1981 – Hansen shows previous cooling trend
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was from aerosols (pollution)
1985 – Ice cores confirm correlation of CO2 and
temperature
1990 - First IPCC report: world has been
warming and future warming seems likely
1995 - Second IPCC report detects "signature"
of human-caused greenhouse effect warming
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History and Background
• 2001 - Third IPCC report: unprecedented global
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warming
2002 - Studies find surprisingly strong "global
dimming" (pollution) has masked intensity of
greenhouse warming
2005 - Kyoto treaty goes into effect
2007 - Fourth IPCC report: unequivocal warming
2007 - CO2 at 382 ppm; T = 14.5°C (up 32%)
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Annual Average Global Surface
Temperature Anomalies 1880-2006
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Annual Average Global Surface
Temperature Anomalies 1880-2006
Warming
Warming
Cooling from Pollution
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Scientists know with virtual
certainty that:
• Human activities are changing the composition
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of Earth's atmosphere.
The atmospheric buildup of CO2 and other
greenhouse gases is largely the result of human
activities.
An “unequivocal” warming trend of about 1.0 to
1.7°F occurred from 1906-2005.
The major greenhouse gases emitted by human
activities remain in the atmosphere for periods
ranging from decades to centuries.
Increasing greenhouse gas concentrations tend
to warm the planet.
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Body of Evidence
• Increase of global average air temperature
• Increase is ocean water temperatures
• Decrease in Arctic sea-ice extent/thickness
• Decrease in glacier/ice cap extent/mass
• Rising global mean seal level
• Changes in freeze/thaw, precipitation, etc.
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FAQ 9.2, F
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Other Climate Variables
• Oceans are becoming more acidic (CO2)
• “Observational evidence from all
continents and most oceans shows that
many natural systems are being affected”
– Permafrost: melting, instability, ecosystems
– Ecosystems: early spring, animal ranges
– Migrations: timing and extent
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What’s Not Certain?
• How much warming will occur
• How fast it will occur
• How the warming will affect the rest of
the climate system
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Summary of Current State
• “Warming of the climate system is
unequivocal”
• Directly related to human activities
• Directly related to increases in GHGs
• Global effects already visible
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Sources
• http://www.aip.org/history/climate/timeline.htm
• Observations of climate change: The 2007 IPCC Assessment,
Testimony of Dr. Kevin E. Trenberth, Committee on Science and
Technology, United States House of Representatives, February 8,
2007
• IPCC, 1996: Climate Change 1995: The Science of Climate Change.
Eds. J. T. Houghton et al., Cambridge University Press, Cambridge,
U.K. 572 pp.
• IPCC, 2001: Climate Change 2001: The Scientific Basis. Eds. J. T.
Houghton, et al., Cambridge University Press, Cambridge, U.K. 881
pp.
• IPCC, 2007: Climate Change 2007: The Scientific Basis. Eds. S.
Solomon, et al., Cambridge University Press, Cambridge, U.K. (in
press).
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Sources
• http://www.epa.gov/climatechange/science/index.html
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