Compiled by scientists from 13 federal agencies, a new report claims human activity significantly contributed to rising temperatures and more extreme weather.
The findings, which appear to contradict the Trump administration's position that it's unclear whether climate change is caused by humans, came as part of a congressionally mandated National Climate Assessment that scientists feared President Donald Trump might try to suppress.
The New York Times obtained a copy of the report, which claims it is “extremely likely” that human activity contributed to more than half of global mean temperature increases since 1951.
“Many lines of evidence demonstrate that human activities, especially emissions of greenhouse (heat-trapping) gases, are primarily responsible for recent observed climate change,” the assessment's authors wrote.
That conclusion contravened Environmental Protection Agency Secretary Scott Pruitt's publicly held belief that global warming was not primarily caused by carbon dioxide. Pruitt's agency, along with 12 others, must approve the report before it's released.
According to the Times, the study conveyed that human activity had a widespread effect on the United States:
In the United States, the report concludes with “very high” confidence that the number and severity of cool nights have decreased since the 1960s, while the frequency and severity of warm days have increased. Extreme cold waves, it says, are less common since the 1980s, while extreme heat waves are more common.
The study examines every corner of the United States and finds that all of it was touched by climate change. The average annual temperature in the United States will continue to rise, the authors write, making recent record-setting years “relatively common” in the near future. It projects increases of 5.0 to 7.5 degrees Fahrenheit (2.8 to 4.8 degrees Celsius) by the late century, depending on the level of future emissions.
It says the average annual rainfall across the country has increased by about 4 percent since the beginning of the 20th century. Parts of the West, Southwest and Southeast are drying up, while the Southern Plains and the Midwest are getting wetter.
The scientists pushed compliance with the Paris Agreement on climate change and warned that allowing temperatures to rise above 2 degrees Celsius could have catastrophic consequences.