Thirty-one major American scientific organizations sent a letter to Congress on Tuesday emphasizing the overwhelming consensus on climate change science and the urgent need for climate action. The letter served as a scientific counterpoint to recent actions by Congress designed to question that consensus.

Reminding members of Congress that "rigorous scientific research concludes that the greenhouse gases emitted by human activities are the primary driver" of global warming, they cited nearly universal support for the scientific consensus as expressed by the U.S. National Academies, the U.S. Global Change Research Program and the U.N.'s Intergovernmental Panel on Climate Change.

"To reduce the risk of the most severe impacts of climate change, greenhouse gas emissions must be substantially reduced," said the letter, which was endorsed by institutions such as the American Association for the Advancement of Science, the American Geophysical Union and the University Corporation for Atmospheric Research, a nonprofit consortium that includes more than 100 North American universities.

"In addition, adaptation is necessary to address unavoidable consequences for human health and safety, food security, water availability, and national security, among others," the letter continued.

Under Republican leadership, Congress has persistently worked to block President Obama's climate agenda. A report released this spring found that a third of current Congressional representatives and Senators publicly doubt the scientific consensus on global warming.

Republican members of the House Science Committee, led by Lamar Smith (R.-Texas), subpoenaed federal scientists last year after researchers from the National Oceanic and Atmospheric Administration published a study that debunked the idea of a recent "global warming hiatus." More recently, the committee demanded internal communications from the attorneys general investigating ExxonMobil for potential climate-related fraud.

Tuesday's letter to Congress echoes a previous letter written in 2009, which was signed by 18 scientific societies. The updated version includes additional signatories including the Society for the Study of Amphibians and Reptiles and the National Association of Marine Laboratories.

The letter concluded with an offer to help legislators understand the science: "We, in the scientific community, are prepared to work with you on the scientific issues important to your deliberations as you seek to address the challenges of our changing climate."