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Global Climate Change: Past and Future Department of Meteorology and Earth and Environmental Systems Institute (ESSI) Penn State University Le Moyne College Syracuse, New York February 3, 2006 `The balance of evidence suggests that there is a discernible human influence on global climate ' Intergovernmental Panel on Climate Change (United Nations), Second Assessment Report, 1996 `There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activity' Intergovernmental Panel on Climate Change (United Nations), Third Assessment Report, 2001 THE DATA Surface Temperature Changes Climatic Research Unit (‘CRU’), University of East Anglia CO2 Related? Greenhouse Gases and Warming TREE RINGS CORALS ICE CORES VARVED LAKE SEDIMENTS HISTORICAL DOCUMENTS RECONSTRUCTED GLOBAL TEMPERATURE PATTERNS Reconstructed Surface Temperatures Climate Change 2001: The Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 2001 From “Wikipedia” Reconstructions of Northern Hemisphere mean temperatures for the last 1000 years and instrumental record (black line) CLIMATE MODELS The climate represents a coupled system consisting of an atmosphere, hydrosphere, biosphere, and cryosphere General Circulation Models take into account the full threedimensional structure of the atmosphere and ocean GCMs do a fairly good job of describing the seasonal cycle in surface temperature This alone doesn’t guarantee that they should do a good job in describing climate change! January Temp (observations) January Temp (model) Modeled Internal Natural Variability Observations INFLUENCE OF EXTERNAL FACTORS The climate is governed by external factors, including the intensity of solar output and volcanic aerosols and greenhouse gas concentrations Solar Variations The climate is governed by external factors, including the intensity of solar output and volcanic aerosols and greenhouse gas concentrations Volcanoes The climate is governed by external factors, including the intensity of solar output and volcanic aerosols and greenhouse gas concentrations The climate is governed by external factors, including the intensity of solar output and volcanic aerosols and greenhouse gas concentrations GREENHOUSE EFFECT? ENHANCED GREENHOUSE EFFECT? SIMULATIONS OF CLIMATE CHANGE Simulated Annual Global Mean Surface Temperatures Climate Change 2001: The Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 2001 Forced Model simulations Simulated Annual Global Mean Surface Temperatures Climate Change 2001: The Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 2001 Forced Model simulations Simulated Annual Global Mean Surface Temperatures Climate Change 2001: The Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 2001 Forced Model simulations Future Surface Temperatures Trends? Climate Change 2001: The Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 2001 Possible Impacts: North American Drought 1998 Global Temperature Pattern El Nino and North American Drought El Nino vs. North American Drought over the Past Century Increased Drought Less Drought La Nina El Nino Courtesy of E.Cook Possible Impacts: Destructive Potential of Atlantic Hurricanes Katrina (Aug 28 ’05) Possible Impacts: Destructive Potential of Atlantic Hurricanes Rita (Sep 21 ’05) Possible Impacts: Destructive Potential of Atlantic Hurricanes Wilma (Oct 19 ’05) Hurricane Statistics P. J. Webster, G. J. Holland, J. A. Curry, H.-R. Chang Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment, Science, 309, Issue 5742, 1844-1846 , 2005. Climate Model Predictions Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment, P. J. Webster, G. J. Holland, J. A. Curry, H.-R. Chang, Science, Vol 309, Issue 5742, 1844-1846 , 16 September 2005. [source: NOAA Climate Prediction Center] [source: NOAA Climate Prediction Center] Climatological Surface Temperatures January [source: NOAA Climate Prediction Center] Surface Temperature Pattern January ’06 [source: NOAA Climate Prediction Center] Surface Temperature Anomaly Pattern January ’06 Climate Change 2001: The Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 2001 Temperature Anomaly Pattern (January ’06) CONCLUSIONS •Recent global surface temperatures are unprecedented this century, and likely at least the past millennium •It is difficult to explain the recent surface warming in terms of natural climate variability •Recent surface warming is largely consistent with simulations of the effects of anthropogenic influence on climate •Possible impacts of anthropogenic climate change this century include increased drought conditions in the western U.S. and more destructive Atlantic tropical storms and Hurricanes