The term climate change has been used to describe and discuss temperature changes and changes in weather patterns. But what is climate change? Climate change occurs as a result of an average increase or decrease in the Earth’s temperature, which can lead to changes in rainfall patterns, changes in sea level, and a wide range of impacts on plants, wildlife, and humans. Climate change is linked with other environmental issues such as air quality, forestry, ozone depletion and biodiversity (Intergovernmental Panel on Climate Change/IPCC).

According to the National Academy of Sciences, the Earth's surface temperature has risen by about 1 degree Fahrenheit in the past century, with increased warming during the past two decades. Scientists expect that the average global surface temperature could rise 1 to 4.5°F (0.6 to 2.5°C) in the next fifty years, and 2.2 to 10°F (1.4 to 5.8°C) in the next century, with significant regional variation.

The U.S. Environmental Protection Agency suggests that there is new and stronger evidence that most of the warming over the last 50 years is attributable to human activities. Human activities have altered the chemical composition of the atmosphere through the buildup of greenhouse gases - primarily carbon dioxide, methane, and nitrous oxide.

Video: Global Warming (WMV)

International Geosphere-Biosphere Programme: Global Change

They have developed a Climate Change Index that is a composite of four major indicators of climate change. Video and other visuals here.

Greenwire: The Leader in Energy & Environmental Policy News

Environment & Energy Publishing is the leading source for comprehensive, daily coverage of environmental and energy politics and policy. Every day, E&E's hard-hitting, original reporting plugs subscribers into the issues facing the White House, Congress, the courts, federal agencies and the states.

ClimateWire: The Politics and Business of Climate Change

E&E's latest publication, ClimateWire, is designed to bring readers unmatched coverage of the debate over climate policy and its effects on business, the environment and society. Climate issues have become so pervasive, and our clients' interest in climate change has become so intense, that developing ClimateWire became an inevitable means to expand and enhance E&E's already top-tier coverage of this critical issue area.

Real Climate: Climate Science from Climate Scientists

RealClimate is a commentary site on climate science by working climate scientists for the interested public and journalists. They aim to provide a quick response to developing stories and provide the context sometimes missing in mainstream commentary.

Carbon Disclosure Project

The Carbon Disclosure Project (CDP) is an independent not-for-profit organization aiming to create a lasting relationship between shareholders and corporations regarding the implications for shareholder value and commercial operations presented by climate change. Its goal is to facilitate a dialogue, supported by quality information, from which a rational response to climate change will emerge.

Common Challenge, Environmental Response: A Roadmap for U.S.-China Cooperation on Energy and Climate Change

January 2009 report by the Asia Society Center on U.S.-China Relations and the Pew Center on Global Climate Change.