The authors note that thousands of studies, conducted by tens of thousands of scientists, have documented climate changes on land and in the air. Many lines of evidence demonstrate that human activities, especially emissions of greenhouse (heat-trapping) gases, are primarily responsible for recent observed climate change, they wrote.
The report was completed this year and is a special science section of the National Climate Assessment, which is congressionally mandated every four years. The National Academy of Sciences has signed off on the draft report, and the authors are awaiting permission from the Trump administration to release it.
One government scientist who worked on the report, Katharine Hayhoe, a professor of political science at Texas Tech University, called the conclusions among the most comprehensive climate science reports to be published. Another scientist involved in the process, who spoke to The New York Times on the condition of anonymity, said he and others were concerned that it would be suppressed.
