Draft U.S. report says extreme storms driven by climate change

Directly contradicting President Donald Trump, a draft report produced by 13 federal agencies concludes that the United States is already feeling the negative impacts of climate change, with a stark increase in the frequency of heat waves, heavy rains and other extreme weather over the last four decades.

The preliminary report summarizes the current state of the science for the upcoming National Climate Assessment. Trump and his Cabinet have expressed public doubts that the warming is being primarily driven by man-made carbon pollution and will have serious consequences for Americans.

An early version of the report, a copy of which was obtained by The Associated Press, was distributed widely in December for review by leading scientists. The New York Times published a copy Monday.

The U.S. Global Change Research Program, which will edit and produce the final report, did not respond to phone and emails seeking comment on Tuesday.

The assessment has generally been released every four years under a federal initiative mandated by Congress in 1990. The current draft, targeted for release later this year, largely builds on the conclusions of the 2014 assessment released under the Obama administration.

The assessment said global temperatures will continue to rise without steep reductions in the burning of fossil fuels, with increasingly negative impacts. Worldwide, 15 of the last 16 years have been the warmest years on record. Today, the National Oceanic and Atmospheric Administration said 2017 is on track to be the second warmest for the United States.

The report calls the long-term evidence that global warming is being driven by human activities “unambiguous.’’

“There are no alternative explanations, and no natural cycles are found in the observational record that can explain the observed changes in climate,’’ the report said, citing thousands of studies.