WASHINGTON — With wildfires raging across the West, climate change took center stage in the race for the White House on Monday as former Vice President Joseph R. Biden Jr. called President Trump a “climate arsonist” while the president said that “I don’t think science knows” what is actually happening.
A day of dueling appearances laid out the stark differences between the two candidates, an incumbent president who has long scorned climate change as a hoax and rolled back environmental regulations and a challenger who has called for an aggressive campaign to curb the greenhouse gases blamed for increasingly extreme weather.
Mr. Trump flew to California after weeks of public silence about the flames that have forced hundreds of thousands of people from their homes, wiped out communities and forests, burned millions of acres, shrouded the region in smoke and left at least 27 people dead. But even when confronted by California’s governor and other state officials, the president insisted on attributing the crisis solely to poor forest management, not climate change.
Mr. Biden, for his part, assailed Mr. Trump’s record on the climate, asserting that the president’s inaction and denial had fed destruction, citing not just the current emergency on the West Coast but flooding in the Midwest and hurricanes along the Gulf Coast. In an outdoor speech at a museum in Wilmington, Del., the Democratic presidential nominee sought to paint a second Trump term as a danger to the nation’s suburbs, flipping an attack on him by the president.
“If we have four more years of Trump’s climate denial, how many suburbs will be burned in wildfires?” Mr. Biden asked. “How many suburban neighborhoods will have been flooded out? How many suburbs will have been blown away in superstorms? If you give a climate arsonist four more years in the White House, why would anyone be surprised if we have more of America ablaze?”
The politicking came as firefighting teams across the West Coast battled shifting winds and drier weather on Monday, sparking additional fire fronts that threatened to make new kindling out of forests and cover more of the country with hazardous smoke and falling ash. By Monday afternoon, haze had spread across much of the United States and could be seen over New York and Washington.
Heavy smoke kept some firefighting aircraft grounded as fire pushed into new areas, prompting fresh evacuations in Idaho, Oregon and California.
In Oregon, with a confirmed death toll of 10 along with 22 others missing, Gov. Kate Brown said the state was getting firefighting support from as far as North Dakota and Michigan. She expressed gratitude for the national assistance, saying the state could use all the help it could get. “Without question, our state has been pushed to its limits,” Ms. Brown said.
Doug Grafe, the chief of fire protection at the Oregon Department of Forestry, said crews had made progress containing fires. But he said rains anticipated to fall Monday were not materializing and winds threatened to exacerbate fire conditions in some areas. Mr. Grafe said the rains that may now come on Wednesday or Thursday could also include lightning, raising the danger of new fires.
Mr. Trump, who had come under intense criticism for barely addressing the crisis before, interrupted a western campaign swing to make a two-hour visit to an airport in McClellan Park outside Sacramento, where Air Force One descended through a smoky haze. Not far away, one of the biggest fires, now largely contained, recently burned more than 363,000 acres.
As soon as the president disembarked from the plane at Sacramento McClellan Airport, where the stench of smoke filled the air, he did not wait for his scheduled briefing to tell reporters that the cause of the conflagration was poor forest management, not climate change.
“When trees fall down after a short period of time, they become very dry — really like a matchstick,” Mr. Trump said. “And they can explode. Also leaves. When you have dried leaves on the ground, it’s just fuel for the fires.”
At his subsequent briefing, however, Gov. Gavin Newsom and his top environmental adviser pushed the president to acknowledge the role of climate change. Mr. Newsom, a Democrat, made a point of doing so exceedingly politely, reaffirming his working relationship with the president, thanking him for federal help and agreeing that forest management needed to be improved.
But Mr. Newsom noted that only 3 percent of land in California is under state control while 57 percent is federal forest land, meaning under the president’s management as governed by federal law.
“As you suggest, the working relationship I value,” Mr. Newsom said. But he said climate change clearly was a factor. “Something’s happening to the plumbing of the world, and we come from a perspective, humbly, where we submit the science is in and observed evidence is self-evident that climate change is real, and that is exacerbating this.”
He went on: “And so I think there’s an area of at least commonality on vegetation, forest management. But please respect — and I know you do — the difference of opinion out here as it relates to this fundamental issue on the issue of climate change.”
Mr. Trump did not argue the point. “Absolutely,” he said, and then turned the floor over to another briefer.
But Wade Crowfoot, California’s secretary for natural resources, pressed Mr. Trump more bluntly. “If we ignore that science and sort of put our head in the sand and think it’s all about vegetation management, we’re not going to succeed together protecting Californians,” he told the president.
This time, Mr. Trump rejected the premise. “It’ll start getting cooler,” he insisted. “You just watch.”
“I wish science agreed with you,” Mr. Crowfoot replied.
“Well, I don’t think science knows, actually,” Mr. Trump retorted, maintaining a tense grin.
Other California officials who were not present rejected Mr. Trump’s view. Mayor Darrell Steinberg of Sacramento said it was a positive development that the president made the trip to demonstrate concern. “Showing up matters,” he said in an interview. “But more important is what you actually do. The country desperately needs national leadership around the climate emergency.”
Some environmental specialists said that Mr. Trump had a point about forest management but that it should not be an excuse to deny climate science and refuse to take action.
“Raking the leaves and forest floors is really inane. That doesn’t make sense at all,” said Ralph Propper, the president of the Environmental Council of Sacramento. “We’re seeing what was predicted, which is more extremes of weather.”
Mr. Trump got some backing from hundreds of supporters who gathered outside the airport, some of them echoing his point about culling forests to prevent the kind of outbreak consuming the region. “I think they should have been cutting trees” ahead of fire season, said Rachel Moses, 43, of Roseville, Calif., who was wearing a pink Trump hat and brought her two sons with her.
Experts say climate change, the management of public lands and decisions over where to site housing all contribute to wildfires. Mr. Trump has exclusively blamed poor forest management and last year issued an executive order directing agencies to cut down more trees, arguing that expanding timber harvesting would reduce forest fires.
Mr. Biden, on the other hand, has proposed spending $2 trillion over four years to escalate the use of clean energy and ultimately phase out the burning of oil, gas and coal. He has pledged to build 500,000 electric vehicle charging stations, build 1.5 million new energy-efficient homes and eliminate carbon pollution from the power sector by 2035.
In his speech at the Delaware Museum of Natural History, Mr. Biden accused Mr. Trump of making the country more vulnerable by denying climate change. He made a case for treating the reduction of fossil fuel emissions as a nonpartisan issue that could create manufacturing jobs while preserving the planet.
“We have to act as a nation,” Mr. Biden said. “It shouldn’t be so bad that millions of Americans live in the shadow of an orange sky, and they’re left asking: ‘Is doomsday here?’”
Mr. Biden also sought to tie Mr. Trump’s rejection of the scientific consensus on climate to his handling of the coronavirus pandemic.
“I think this is a larger narrative that you’re just now starting to see emerge out of the Biden campaign,” said Anthony Leiserowitz, the director of the Yale Program on Climate Change Communication. “Climate change becomes Exhibit A in a much broader case he’s making about the fact that Donald Trump is out of touch with reality.”
Whit Ayres, a Republican political consultant, said Mr. Trump was not helping himself politically by continuing to reject climate science. “It’s gotten to the point,” he said, “where denying the fundamental reality of climate change is no longer a credible position.”
Peter Baker and Lisa Friedman reported from Washington, and Thomas Kaplan from Connecticut. Kellen Browning contributed reporting from McClellan Park, Calif., and Dave Philipps from Colorado Springs.