The Current State of Our Climate

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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

• 1800s - CO2 at 290 ppm T 13.6C
• 1824 - Fourier discovers natural greenhouse
  effect of atmosphere
• 1896 - Swedish scientist Arrhenius predicts
  greenhouse warming from CO2
• 1960 - CO2 at 315 ppm (up 9 from 1800)
• 1970s - Unusual weather creates speculation on
  global warming/cooling

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History and Background

• 1981 Hansen shows previous cooling trend 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
  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 14.5C (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 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
  1.7F 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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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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Whats 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.htm
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