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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 1/31/08 Bucknell University 2 History and Background • 1800’s - CO2 at 290 ppm; T = 13.6°C • 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) 1970’s - Unusual weather creates speculation on global warming/cooling 1/31/08 Bucknell University 3 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 1/31/08 Bucknell University 4 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 = 14.5°C (up 32%) 1/31/08 Bucknell University 5 Annual Average Global Surface Temperature Anomalies 1880-2006 1/31/08 Bucknell University 6 Annual Average Global Surface Temperature Anomalies 1880-2006 Warming Warming Cooling from Pollution 1/31/08 Bucknell University 7 1/31/08 Bucknell University 8 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 1.7°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. 1/31/08 Bucknell University 9 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. 1/31/08 Bucknell University 10 1/31/08 Bucknell University FAQ 9.2, F 11 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 1/31/08 Bucknell University 12 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 1/31/08 Bucknell University 13 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 1/31/08 Bucknell University 14 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). 1/31/08 Bucknell University 15 Sources • http://www.epa.gov/climatechange/science/index.html 1/31/08 Bucknell University 16