The Consensus on Global Warming

American Association for the Advancement of Science:

The scientific evidence is clear: global climate change caused by human activities is occurring now, and it is a growing threat to society.

American Geophysical Union:

The Earth's climate is now clearly out of balance and is warming. Many components of the climate system-including the temperatures of the atmosphere, land and ocean, the extent of sea ice and mountain glaciers, the sea level, the distribution of precipitation, and the length of seasons-are now changing at rates and in patterns that are not natural and are best explained by the increased atmospheric abundances of greenhouse gases and aerosols generated by human activity during the 20th century.

National Oceanic and Atmospheric Administration:

The 2009 State of the Climate report released today draws on data for 10 key climate indicators that all point to the same finding: the scientific evidence that our world is warming is unmistakable.

American Physical Society:

The evidence is incontrovertible: Global warming is occurring. If no mitigating actions are taken, significant disruptions in the Earth’s physical and ecological systems, social systems, security and human health are likely to occur. We must reduce emissions of greenhouse gases beginning now.

American Meteorological Society:

Indeed, strong observational evidence and results from modeling studies indicate that, at least over the last 50 years, human activities are a major contributor to climate change.