EPA’s Scenarios for Future Greenhouse Gas Emissions and Global Warming

Abstract

While it is not possible to stabilize greenhouse gas concentrations immediately, a global commitment to reducing emissions would decrease the risks of global warming regardless of uncertainties about the response of the climate system. Scenario analyses conducted by EPA for a Report to Congress on Policy Options for Stabilizing Global Climate indicate that if no policies to limit greenhouse gas emissions are undertaken, the equivalent of a doubling of carbon dioxide would occur between 2030 and 2040, and the Earth might be committed to a global warming of 2-4°C(3-7°F) by 2025 and 3-6°C(4-10°F) by 2050. Early application of existing and emergingtechnologies designed among other things, to increase the efficiency of energy use, expand the use of non-fossil energy sources, reverse deforestation, and phase out chlorofluorocarbons, could reduce the global warming commitment in 2025 by about one-fourth, and the rate of climatic change during the next century by at least 60%. A global commitment to rapidly reducing greenhouse gas emissions could stabilize the concentrations of these gases by the middle of the next century, perhaps limiting global warming to less than 2°C(3°F).