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Global Warming: The Facts What is global warming? o The change in Earth's temperature caused by the buming of oil, coal and natural gas and changes in land surface properties. o Greenhouse gasses (Carbon Dioxide, Methane, Chlorofluorocarbons and Nitrous Oxide and aerosols trap heat in the atmosphere. o Snow and ice reflect 90% of the heat that hits them back into the atmosphere, but water absorbs 90% ofthe radiation that hits it. o Carbon Dioxide (C02) is the most important greenhouse gas. The increased concentration in the atmospheric concentration is due to use of fossil fuels, with land use playing a smaller role. What is the evidence that global warming is happening? o 11 ofthe last 12 years have been among the 12 wannest years on record o The concentrations of all of the greenhouse gasses mentioned above have increased since the industrial revolution. The CO2 concentration has gone fi'om 280 palis per million (ppm) to 379 ppm, and the methane concentration from.8 to 1.7 ppm. o The average atmospheric water vapor content has increased since the 1980s over land and sea, because Walmer air can hold more water vapor. o The average temperature of the global ocean has increased since 1961 to the depth of at least 3 kilometers, causing the water to expand and sea level to rise. o The number of category 4 and 5 hurricanes has doubled in the last 30 years. o Mountain glaciers and snow cover have declined, and the rate of melting is speeding up; the flow of ice from glaciers in Greenland has more that doubled in the past decade. o At least 279 species of plants and animals have reacted to the change in temperatures by moving closer to the poles. What will be the effects of global warming? o For the next 2 decades a warming of about 0.2' C per decade is expected/ o Continued greenhouse gas emissions at or above current rates would cause further warming and induce many changes in the climate that are very likely to be greater that those observed during the 20th century. o Models that do not take into account rapid changes in ice flow predict a rise in sea level of up to 59 cm.in 90 years; if there is a loss in the ice shelf in Greenland or Antarctica, the global sea level could rise up to 20 feet. . Hot extremes, heat waves and heavy precipitation events will become more frequent. o Droughts and wildfires will occur more often. What can we do? o Many steps are individual, like energy efficient appliances and light bulbs, hybrid cars and carpooling, recycling, buying green power, alld buying environmentally friendly products. o The Kyoto Treaty is an intemational treaty that is designed to reduce the emission of greenhouse gasses. It calls on industrialized countries to reduce their combined emissions of six major greenhouse gasses by 2012 to their levels in 1990. o The United States govemment hasn't signed this treaty, but individual cities can take the initiative to do this by themselves by joining the cool cities campaign. Sources: The Intergovernmental Panel on Climate Change Summary for policy makers; www-ipcc.chl, www.c1imatecrisis.net. Opposing viewooints- Global Warming, edited by Cynthia A. Bily, Greenhaven Press, 2006.