"There is concern that human activities are affecting the heat/energy-exchange balance between Earth, the atmosphere, and space, and inducing global climate change, often termed 'global warming.' Human activities, particularly the burning of fossil fuels, have contributed to increased atmospheric carbon dioxide (CO2) and other trace greenhouse gases. If these gases continue to accumulate in the atmosphere at current rates, most scientists believe significant global warming would occur through intensification of Earth' s natural heat-trapping 'greenhouse effect.' Possible impacts might be seen as both positive and negative, depending on regional or national variations. [...] In March 2001, the Bush Administration rejected the Kyoto Protocol, and thus the United States is not party to it (and therefore is not subject to its requirements) as it enters into force. President Bush concluded a cabinet-level climate policy review with an announcement in 2002 of a 'new approach' for the United States based on reducing the greenhouse gas intensity (greenhouse gas emissions per unit of GDP) of the U.S. economy. This report briefly reviews the status of climate science, international negotiations, and congressional activity focused specifically on climate change."
CRS Issue Brief for Congress, IB89005