As California's catastrophic wildfires recede and Americans on the east coast rebuild after two hurricanes, a new federal report warns these types of extreme weather disasters are worsening in the United States.

Key points: The report was written with help of more than a dozen US government agencies

The report was written with help of more than a dozen US government agencies At odds with the Trump administration's pro-fossil fuels agenda, it says climate change could cost the US economy billions

At odds with the Trump administration's pro-fossil fuels agenda, it says climate change could cost the US economy billions The report says global warming would disproportionately hurt the poor, undermine human health, limit availability of water

The White House report, issued on Friday (Saturday AEDT), also frequently contradicted President Donald Trump.

The National Climate Assessment was written long before deadly fires tore through California this month and Hurricanes Florence and Michael raked the United States' east coast and Florida. California's Camp Fire has killed at least 84 people and destroyed nearly 14,000 homes since it started on November 8.

The report says warming-charged extremes "have already become more frequent, intense, widespread or of long duration".

The federal report says the last few years have smashed records for damaging weather in the US, costing nearly $US400 billion ($553 billion) since 2015.

"Warmer and drier conditions have contributed to an increase in large forest fires in the western United States and interior Alaska," the report says.

Report co-author Katharine Hayhoe, of Texas Tech University, said "we are seeing the things we said would be happening, happen now in real life".

"As a climate scientist it is almost surreal," she said.

The report says climate change will cost the US economy hundreds of billions of dollars by the end of the century, damaging everything from human health to infrastructure and agricultural production.

The report was written with the help of more than a dozen US government agencies and departments, and outlined the projected impacts of global warming in every corner of American society, in a dire warning at odds with the Trump administration's pro-fossil fuels agenda.

"With continued growth in emissions at historic rates, annual losses in some economic sectors are projected to reach hundreds of billions of dollars by the end of the century — more than the current gross domestic product of many US states," according to the report.

It said global warming would disproportionately hurt the poor, broadly undermine human health, damage infrastructure, limit the availability of water, alter coastlines, and boost costs in industries from farming to energy production.

While it said that many of the impacts of climate change — including more frequent and more powerful storms, droughts and flooding — were already underway, the projections of further damage could change if greenhouse gas emissions were sharply curbed.

"Future risks from climate change depend primarily on decisions made today," it says.

The report, the Fourth National Climate Assessment Volume II, supplements a study issued last year that concluded humans are the main cause of global warming, and warned of potentially catastrophic effects to the planet.

Report clashes with Trump administration

The studies clash with policy under Mr Trump, who has been rolling back Obama-era environmental and climate protections to maximise production of domestic fossil fuels, including crude oil, already the highest in the world, above Saudi Arabia and Russia.

President Donald Trump announced the United States' withdrawal from the Paris climate change accord in 2017. ( AP: Andrew Harnik )

Mr Trump last year announced his intention to withdraw the United States from the 2015 Paris Deal agreed by nearly 200 nations to combat climate change, arguing the accord would hurt the US economy and provide little tangible environmental benefit.

Mr Trump and several members of his Cabinet have also repeatedly cast doubt on the science of climate change, arguing the causes and impacts are not yet settled.

Loading

White House spokeswoman Lindsay Walters did not immediately respond to a request for comment.

Loading

Environmental groups said the report reinforced their calls for the United States to take action on climate change.

"This report makes it clear that climate change is not some problem in the distant future. It's happening right now in every part of the country," Brenda Ekwurzel, the director of climate science at the Union of Concerned Scientists and one of the report's authors, said.

Previous research, including from US government scientists, has also concluded climate change could have severe economic consequences, including damage to infrastructure, water supplies and agriculture.

Severe weather and other impacts also increase the risk of disease transmission, decrease air quality, and can increase mental health problems, among other effects.

Thirteen government departments and agencies, from the Agriculture Department to NASA, were part of the committee that compiled the new report.

AP/Reuters