A sweeping new U.S. government report concludes that humans have pushed global temperatures to the highest level seen by modern civilization, defying the Trump administration’s pronouncements that climate change is a hoax or based on unsettled science.

The report, produced by 13 agencies as part of the congressionally required National Climate Assessment, reinforced years of research that shows human activity was the main reason temperatures have soared in the past century — and they are likely to keep climbing, boosting sea levels and threatening environmental disasters.

The report contradicts President Donald Trump's rejection of climate science, his plan to withdraw the U.S. from a global pact to fight climate change and his moves to unwind a slate of policies put in place under former President Barack Obama to reduce greenhouse gas emissions.

“Foremost, we conclude based on extensive evidence, that it is extremely likely that human activities are the dominant causes of global warming,” said David Fahey, one of the lead authors. “For the warming over the last century, there is no convincing alternative explanation for the warming observed."

However, the White House stuck to its stance that climate "has changed and is always changing,” and it pointed to portions of the report about the uncertainty around the Earth’s sensitivity to greenhouse gas emissions.

White House spokesman Raj Shah said in a statement that the Trump administration “supports rigorous scientific analysis and debate,” and the U.S. will continue to promote access to “affordable and reliable energy needed to grow economically,” support technology and infrastructure that reduce emissions and “enable us to address future risks, including climate related risks.”

Fahey, a scientist at the National Oceanic and Atmospheric Administration, told reporters on a conference call that he saw no attempt to influence the report by the Trump administration.

“I’m quite confident to say there’s been no political interference in the scientific messages of this report,” Fahey said.

Virginia Burkett, an Interior Department climate scientist and chair of the subcommittee on Global Change Research, emphasized that the report steered clear of recommending any policies to deal with climate change, saying it was limited to “strictly the science.”

EPA Administrator Scott Pruitt, who said he did not believe that man-made emissions were the main cause of climate change and has moved to eliminate Obama's rules curbing carbon dioxide pollution from power plants, did not comment on the report.

The report was reviewed by scientists at the National Academies, released for public comment and screened by federal agencies under both the Obama and Trump administrations.

Juanita Constible, a special projects director at the Natural Resources Defense Council, said in a blog post the report confirms what many other previous studies had shown.

"It’s essential that our federal leaders in Congress and the Executive Branch take seriously the dire conclusions from the painstaking and authoritative work in the [the report] — and more importantly, to urgently act on the findings," Constible wrote.

Bob Kopp, a climate scientist at Rutgers University and a report contributor, said the findings “reaffirmed that climate change is real, that humans are the dominant cause of warming, and that it is having an effect in the U.S. And those effects will grow more severe as long as we continue to emit carbon dioxide into the atmosphere.”

Sea levels are expected to rise one to four feet by the end of the century and could swell by up to eight feet if emissions of greenhouse gases continue to rise, the Climate Science Special Report says.

Episodes of heavy rainfall are becoming more frequent and intense, and heat waves will become more common. Kopp said the report also shows the U.S. can expect more compounded extreme weather events, like the multiple hurricanes and wildfires that occurred this summer.

Annual global average temperatures are expected to rise by 2.5 degrees Fahrenheit by 2050. And although the growth in global carbon dioxide emissions is slowing, that trend is moving too slowly to keep temperatures below a dangerous tipping point of 3.6 degrees, or 2.0 degrees Celsius, above pre-industrial levels that would see more devastating impacts, the scientists found.

The report is the most comprehensive study since the last National Climate Assessment was published three years ago and the Intergovernmental Panel on Climate Change published its physical science report four years ago, Kopp said.

The U.S. Global Change Research Program, which coordinates the assessment, also released a draft of a second volume, which examines impacts on public health and the environment, and a draft of a report on changes in carbon levels.

The report about how climate change impacts Americans, which will undergo public comment, notes that “Americans are responding to rapid changes affecting their everyday lives and livelihoods,” because of climate change.

Reservoir managers in the Colorado River Basin are adjusting to lower water levels, cities along the Gulf and Atlantic Coasts are seeing more flooding and storm surge from rising seas and heavier rains. Farms in the Midwest are adopting new crop management strategies, and communities in the western U.S. face more wildfires, it notes.

Some risks are already unavoidable while others could be reversed if greenhouse gas emissions decline, according to the report.

“Climate change puts many things Americans care about at risk, both now and in the future, and risks will intensify without action,” the report says.

Originally published by Politico