Below is the test of an open letter from American scientific leaders to United States Senators, October 21, 2009, in which they state that climate change is real, serious, and likely to have worse impacts in the future. After the publication of this letter, there are no national or international scientific organizations that deny that humans are causing climate change.
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Observations throughout the world make it clear that climate change is occurring, and rigorous scientific research demonstrates that the greenhouse gases emitted by human activities are the primary driver. 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. Moreover, there is strong evidence that ongoing climatic change will have broad impacts on society, including the global economy and on the environment. For the United States, climate change impacts include sea level rise for coastal states, greater threats of extreme weather events, and increased risk of regional water scarcity, urban heat waves, western wildfires, and the disturbance of biological systems throughout the country. The severity of climate change impacts is expected to increase substantially in the coming decades.
If we are to avoid the most severe impacts of climate change, emissions of greenhouse gases must be dramatically reduced. In addition, adaptation will be necessary to address those impacts that are already unavoidable. Adaptation efforts include improved infrastructure design, more sustainable management of water and other natural resources, modified agricultural practices, and improved emergency responses to storms, floods, fires and heat waves.
Alan I. Leshner, Executive Director, American Association for the Advancement of Sciences
Thomas Lane, President, American Chemical Society
Timothy L. Grove, President, American Geophysical Union
May R. Berenbaum, President, American Institute of Biological Sciences
Keith Seitter, Executive Director, American Meteorological Society
Mark Alley, President, American Society of Agronomy
Tuan-hua David Ho, President, American Society of Plant Biologists
Sally C. Morton, President, American Statistical Association
Lucinda Johnson, President, Association of Ecosystem Research Centers
Kent E. Holsinger, President, Botanical Society of America
Kenneth Quesenberry, President, Crop Science Society of America
Mary Power, President, Ecological Society of America
William Y. Brown, President, Natural Science Collections Alliance
Brian D. Kloeppel, President, Organization of Biological Field Stations
Douglas N. Arnold, President, Society for Industrial and Applied Mathematics
John Huelsenbeck, President, Society of Systematic Biologists
Paul Bertsch, Soil Science Society of AmericaRichard A. Anthes, President, University Corporation for Atmospheric Research
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