Global Climate Change

Publication Date: May 2006

Publisher: Library of Congress. Congressional Research Service

Author(s):

Research Area: Environment

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Abstract:

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.

A warmer climate would probably have far-reaching effects on agriculture and forestry, managed and unmanaged ecosystems, including natural habitats, human health, water resources, and sea level, depending on climate responses. Although causal relationships between projected long-range global climate trends and record-setting warmth and severe weather events of the past two decades have not been firmly established, attention has been focused on possible extremes of climate change and the need for better understanding of climate processes to improve climate model projections.

The basic policy question remains: Given scientific uncertainties about the magn i t u d e , timing, rate, and regional consequences of potential climatic change, what are the appropriate responses for U.S. and world decision makers? Fossil-fuel combustion is the primary source of CO2 emissions, and also emits other "greenhouse" gases. Because the U.S. economy is so dependent upon energy, and so much of U.S. energy is derived from fossil fuels, reducing these emissions poses major challenges and controversy.

The 1992 United Nations Framework Convention on Climate Change (UNFCCC), which the United States has ratified, called for a "non-binding" voluntary aim for industrialized countries to control atmospheric concentrations of greenhouse gases by stabilizing their emissions at 1990 levels by the year 2000. The 1997 Kyoto Protocol to the UNFCCC goes further, and commits the major industrialized nations that have ratified it to specified, legally binding emissions reductions. On February 16, 2005, the Kyoto Protocol entered into force. According to the UNFCCC Secretariat, as of February 6, 2006, 160 nations and economic regional integration organizations had ratified the Protocol. The European Union instituted its emissions trading system under the Protocol at the beginning of 2005.

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.