WASHINGTON (NYTIMES) - When US President Donald Trump flies to California on Monday (Sept 14) to assess the state's raging forest fires, he will come face to face with the grim consequences of a reality he has stubbornly refused to accept: the devastating effects of a warming planet.

To the global scientific community, the acres of scorched earth and ash-filled skies across the American West are the tragic, but predictable, result of accelerating climate change. Nearly two years ago, federal government scientists concluded that greenhouse gas emissions from burning fossil fuels could triple the frequency of severe fires across the Western states.

But the president has used his time in the nation's highest office to aggressively promote the burning of fossil fuels, chiefly by rolling back or weakening every major federal policy intended to combat dangerous emissions. At the same time, Trump and his senior environmental officials have regularly mocked, denied or minimised the established science of human-caused climate change.

Now, as he battles for a second term in the White House, Trump has doubled down on his anti-climate agenda as a way of appealing to his core supporters. At a rally in Pennsylvania last month, he blamed California's failure to "clean your floors" of leaves, threatening to "make them pay for it because they don't listen to us".

The lethal fires spreading across the West - like the coronavirus that has ravaged the country for months - are a warning for the president that many voters may hold him and his administration accountable for brushing aside scientific experts and failing to effectively mobilise the government to minimise natural disasters that have claimed lives, damaged property and threatened economic prosperity.

"Talk to a firefighter if you think that climate change isn't real," Mayor Eric Garcetti of Los Angeles, a supporter of former Vice-President Joe Biden, Trump's Democratic opponent, said on CNN's "State of the Union" on Sunday. "It seems like this administration are the last vestiges of the Flat Earth Society of this generation."

Trump's climate record is far more aggressive than the laissez-faire environmental policy promoted for years by business interests in his party. Indeed, as he has sought to zealously roll back regulations, even some of the world's largest oil companies and automakers have opposed the moves, saying that they will lead to years of legal uncertainty that could actually harm their bottom lines.

"As an historic figure, he is one of the most culpable men in America contributing to the suffering and death that is now occurring through climate-related tragedy," Jerry Brown, the former California governor who made climate change his signature issue, said in an interview on Sunday, though he was careful not to blame Trump specifically for the fires ravaging his state.

The president's record is also more consequential, experts say, because the amount of planet-warming carbon dioxide trapped in the Earth's atmosphere has now passed the point at which scientists say it would be possible to avert many of the worst effects of global warming - even if tough emissions policies are later enacted.

Biden's presidential campaign is hoping to use Trump's climate positions as a cudgel against him with independents and moderate Republicans. Christine Todd Whitman, the Republican former governor of New Jersey, is backing Biden's candidacy in large part because of the president's environmental policies.

"It's mind-boggling, the ignorance that he displays on this subject," Whitman said in an interview on Sunday. "He doesn't understand climate change. He doesn't particularly believe in science. It's all about him and his reelection." "He doesn't govern for all Americans," she said.

On Saturday, Trump abruptly added the trip to McClellan Park, California, near Sacramento, to be briefed on the fires to an already scheduled West Coast fundraising and campaign swing.

He had come under intense criticism for weeks of silence on the increasingly deadly blazes that are consuming parts of California, Oregon and Washington - three Democratic-led states that he has feuded with for years.

White House officials noted that Trump had signed an executive order in 2018 to minimise the risk of wildfires and urged California and other states to improve forest management.

"Other countries around the world are obsessed with the Paris climate accord, which shackles economies and has done nothing to reduce greenhouse gas emissions, and those on the radical left are pushing the Green New Deal, which would outlaw cows, cars and planes," said Judd Deere, a White House spokesman. He said Trump had put in place "common sense policies that have kept our air, water and environment clean."

The president has continued to take a dim view of climate science throughout his tenure, even as the government he oversees has reinforced the accepted threats to the future of the planet.

In 2017 and 2018, the federal government published a sweeping, two-volume scientific report, the National Climate Assessment, that represents the most authoritative and comprehensive conclusions to date about the causes and effects of climate change in the United States.

The report is clear about the causes - burning fossil fuels - and the effects: It found that the increased drought, flooding, storms and worsening wildfires caused by the warming planet could shrink the US economy by up to 10% by the end of the century.

Two days before the White House published the 2018 volume of that report, Trump mockingly tweeted, "Brutal and Extended Cold Blast could shatter ALL RECORDS - Whatever happened to Global Warming?" In an interview a month before, he said of global warming, "I don't know that it's man-made," and suggested that even as the planet warmed, "it will change back again" - an idea scientists have long debunked.

Trump has also stocked his administration with senior officials who have openly questioned the basic science of climate change. The National Oceanic and Atmospheric Administration, which conducts scientific research on climate change, this year hired as a deputy assistant secretary David Legates, a scientist at the University of Delaware who has questioned human-caused global warming. The hiring of Legates was first reported by NPR.

William Happer, a former senior White House adviser and a Princeton physicist who had gained notoriety in the scientific community for statements that carbon dioxide was beneficial to humanity, began an effort last year to ensure that the next National Climate Assessment did not include worst-case scenarios. Although Happer left the White House last year, that effort is continuing, according to three people familiar with the matter.

And Trump's first appointee to lead the Environmental Protection Agency, Scott Pruitt, declared early in his tenure that carbon dioxide was not a primary contributor to global warming, a statement starkly at odds with the scientific consensus.

"It's interesting to draw the parallels between Covid and climate change," said Philip B. Duffy, the president of the Woodwell Climate Research Centre, who served on the National Academy of Sciences panel that reviewed the National Climate Assessment.

"In both of those cases, Trump personally has refused to recognise the threat." "In both cases, there is no plan to deal with crisis," he added.

Moreover, Trump has steadily dismantled the climate change plan that was already in place by effectively gutting the federal government's authority to do anything to lower greenhouse gas pollution.

"We had at the end of the Obama administration the first-ever federalwide regulatory regime on climate," said David G. Victor, the director of the Laboratory on International Law and Regulation at the University of California, San Diego. "Most of that, the Trump administration has actively rolled back."

In his first months in office, Trump announced that he would withdraw the US from the 2015 Paris climate accord, under which nearly every country in the world had pledged to reduce emissions of planet-warming pollution.

Domestically, Trump directed Andrew Wheeler, the current head of the EPA, to dismantle a suite of major climate change regulations put in place by the Obama administration, which had been designed to target pollution from the nation's three largest sources of greenhouse emissions: coal-fired power plants, auto tailpipes and oil and gas drilling sites. Taken together, those rules represented the country's first significant step towards reducing greenhouse gases, while putting the world's largest economy at the forefront of the global effort to fight climate change.

Now they are in shambles.