Eighteen science organizations said observations make it "clear" climate change is occurring because of greenhouse gases released due to human activity.
The letter states:
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 climate change will have broad impacts on society, including the global economy and on the environment.
A who's-who of science organizations signed the letter sent to the Senate as they consider climate change legislation. Those organizations included:
One of the signatorees, UCAR, is a "a nonprofit organization governed by 75 member universities granting Ph.D.s in atmospheric and related Earth system sciences."