More than 1,700 of the nation's most prominent scientists and economists today released a joint statement calling on policymakers to require immediate, deep reductions in heat-trapping emissions that cause global warming.

"The longer we wait, the harder and more costly it will be to limit climate change," said the statement, which calls for a reduction in US emissions of 80 percent below 2000 levels by 2050.

"There is a strong consensus that we must do something about reducing the emissions that cause global warming," said James McCarthy, president of the American Association for the Advancement of Science and one of the statement's authors.

Besides McCarthy, the statement authors include Mario Molina, a Nobel Prize winner in chemistry; Peter Frumhoff, director of science and policy at the Union of Concerned Scientists (UCS) and an Intergovernmental Panel on Climate Change (IPCC) lead author; Stephen Schneider, a Stanford University climatologist and a member of the National Academy of Sciences (NAS); and Geoff Heal, an economist at Columbia University's Business School. The signatories, compiled by UCS, include six Nobel Prize winners in science or economics, 31 NAS members, and more than 100 IPCC authors and editors, who all shared the 2007 Nobel Peace Prize with Al Gore.

A full copy of the letter and the criteria for those endorsing the letter can be downloaded here (pdf).