Greenhouse Effect and Global Warming

Greenhouse Effect The atmosphere is transparent to incoming solar radiation (short wave, high energy), but opaque to outgoing terrestrial radiation(longer waves, lower energy). Black body radiator = perfect absorber and emitter or energy; wavelength depends on the temperature of the body. Albedo = measure of reflectivity. For example, snow has a high albedo and asphalt has a low albedo.

Energy Balance

Greenhouse Gases Carbon dioxide – CO2 Water vapor – H2O Methane – CH4 Nitrous oxide – N2O Freons – CFCs (totally anthropogenic)

Current GHG Concentrations Updated September 2001

Global Warming An increase in global temperatures due to increases in the concentrations of greenhouse gases Appears to be a direct relationship between CO2 concentrations and increases in global temperatures Relationship between CO2 and global temperatures was first noted in 1896 by Svante Arrhenius NOT CAUSED BY STRATOSPHERIC OZONE DEPLETION

Causes Combustion of fossil fuels Deforestation Fertilizers CFCs Slash and burn techniques release CO2 Fewer trees, less photosynthesis Fertilizers CFCs Methane

Atmospheric carbon dioxide (CO2) concentrations (1750 to present) Preindustrial atmospheric CO2 concentrations were approximately 275 parts per million. Today concentrations are approximately 367 ppmv, an increase of over 30 percent. Data Source: C.D. Keeling and T.P. Whorf, Atmospheric CO2 Concentrations (ppmv) derived from in situ air samples collected at Mauna Loa Observatory, Hawaii, Scripps Institute of Oceanography, August 1998. A. Neftel et al, Historical CO2 Record from the Siple Station Ice Core, Physics Institute, University of Bern, Switzerland, September 1994. See http://cdiac.esd.ornl.gov/trends/co2/contents.htm Data Source: C.D. Keeling and T.P. Whorf, Atmospheric CO2 Concentrations (ppmv) derived from in situ air samples collected at Mauna Loa Observatory, Hawaii, Scripps Institute of Oceanography, August 1998. A. Neftel et al, Historical CO2 Record from the Siple Station Ice Core, Physics Institute, University of Bern, Switzerland, September 1994. See http://cdiac.esd.ornl.gov/trends/co2/contents.htm

Cumulative carbon emissions, 1950-1996 In terms of historical contributions to the atmospheric buildup of emissions, the industrialized countries like the US have contributed roughly 80 percent of the carbon dioxide buildup in the atmosphere to date. On a country-by-country basis, the comparisons between the rich and poor countries are even more stark. Since 1950, the US has emitted a cumulative total of roughly 50 billion tons of carbon, while China (4.5 times more populous) and India (3.5 times more populous) have emitted only 15 and 4 billion tons respectively. Data Source: Marland et al, 1999. Carbon Dioxide Information Analysis Center. Data Source: Marland et al, 1999. Carbon Dioxide Information Analysis Center.

Variations in the Earth’s surface temperature

FACTORS AFFECTING GLOBAL TEMPERATURES Incr. carbon dioxide  incr. temperature Deforestation  Incr. carbon dioxide  incr. temperature Incr. ocean temperature  incr. land temperature Incr. particulate matterincr. albedo decr. temp.

Impacts Rise in sea level Climatic shifts Shifts in agriculture Thermal expansion of the oceans Melting ice caps and glaciers Climatic shifts Shifts in agriculture Increase in disease Declines in biodiversity Coral bleaching

Potential Impacts of Global Warming Increased deaths from heat and disease Disruption of food and water supplies Spread of tropical diseases to temperate areas Increased respiratory disease Increased water pollution from coastal flooding Human Health Rising sea levels Flooding of low-lying islands and coastal cities Flooding of coastal estuaries, wetlands, and coral reefs Beach erosion Disruption of coastal fisheries Contamination of coastal aquifiers with salt water Sea Level and Coastal Areas Changes in forest composition and locations Disappearance of some forests Increased fires from drying Loss of wildlife habitat and species Forests Changes in water supply Decreased water quality Increased drought Increased flooding Water Resources Shifts in food-growing areas Changes in crop yields Increased irrigation demands Increased pests, crop diseases, and weeds in warmer areas Agriculture Extinction of some plant and animal species Loss of habitats Disruption of aquatic life Biodiversity Prolonged heat waves and droughts More intense hurricanes, typhoons, tornadoes, and violent storms Weather Extremes Increased deaths More environmental refugees Increased migration Human Population

Sea Level Projections

Reducing GH Emissions

Solutions

Global Agreements IPCC – Intergovernmental Panel on Climate Change  1988 UNEP Rio de Janeiro  1992 Kyoto Protocol  1997 Ratified Nov. 2006 U.S. and Australia have not signed the treaty

U.S. Position Bush Sr. (1988 – 1992) Clinton (1992 – 2000) Bush Jr. (2000 – 2008)