The American Institute of Biological Sciences (AIBS) and other leading scientific organizations have reaffirmed the scientific consensus that climate change is occurring and is primarily caused by human activities. In a statement sent to all U.S. Senators on 21 October 2009, the presidents of 18 scientific organizations stated that “rigorous scientific research” demonstrates that the greenhouse gases emitted by human activities are the “primary driver” of climate change. “These conclusions are based on multiple independent lines of evidence, and contrary assertions are inconsistent with an objective assessment of the vast body of peer-reviewed science,” the scientists wrote.

Dr. May Berenbaum, President of AIBS, signed the letter on behalf of the society. “The evidence that human activities contribute to global climate change is compellingly consistent and clear; constructive human activities to stem or reverse these changes are now urgently needed,” she said.

The letter called attention to the impacts of climate change on human society, the economy, and the environment. The “broad impacts” of climate change include sea level rise, greater threats of extreme weather events, and increased risk of regional water scarcity, wildfires, and the disturbance of biological systems throughout the United States. “[T]o avoid the most severe impacts of climate change, emissions of greenhouse gases must be dramatically reduced,” the letter stated. “In addition, adaptation will be necessary to address those impacts that are already unavoidable.”

The scientific organizations that sent the letter represent the breadth of the scientific community. Collectively, these organizations serve more than 10 million scientists. Ten AIBS member organizations have already signed the statement.

To read the complete statement, please visit


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