The claim: Wildfires on the West Coast stop at the borders to Canada and Mexico.
In just a few weeks, California has experienced six of the state's 20 largest wildfires in modern history.
Gov. Gavin Newsom has declared the usual wildfire season "the reality of the ravages of climate change."
But some are hesitant to believe him — and have taken to Facebook to express their doubts.
A since-deleted screenshot of a tweet from actor James Woods displays a map of the wildfires throughout the Western U.S., with no fires marked in nearby Mexico or Canada.
"Hey Governor Newsom, why does 'climate change' stop abruptly at the Canadian border?" the tweet reads. The tweet was posted to Facebook by Amiri King.
Others used the maps to bolster the claims that fires in Washington and Oregon were set by anti-fascist activists, which USA TODAY has already debunked.
"Let's just say I'm skeptical that 50 fires started in 3 states but stopped at the Canadian and Mexico border was due to climate change," another post on Facebook reads.
The users behind the posts did not respond to requests from USA TODAY for comment.
There are fires on both sides of the border, though some maps only show the U.S.
In reality, there are fires on both sides of the border. Throughout the summer, Mexico and Canada have experienced fires in their western regions, too — they just aren't marked on some maps that are only intended to show fires in the U.S.
Katharine Hayhoe, a climate scientist and the director of the Texas Tech Climate Center, addressed the issue on Twitter.
"The latest disinformation circling the twittersphere asks why the impacts of climate change appear to stop at the Canadian border," she wrote. "The answer is simple: because US maps only show US data."
A global map from NASA's Fire Information for Resource Management System reveals fires burning up and down the coast, in Canada, the U.S., and Mexico.
Hayhoe also pointed to Canada's National Wildland Fire Situation Report as proof that the crisis extends beyond the United States.
As of Sept. 9, it listed five uncontrolled fires burning in Canada, on top of 11 fires being held and 47 controlled fires. And two highest-priority fires on the website are both in British Columbia, the Western-most province.
Scientists confirm that climate change has exacerbated fires
Scientists have backed up the claim that this season's fires have been worsened by climate change.
Zeke Hausfather, a climate scientist at the Breakthrough Institute, told the Los Angeles Times that summers in California are 2.5 degrees warmer than they were in the 1970s.
“What we’ve been seeing in California are some of the clearest events where we can say this is climate change — that climate change has clearly made this worse,” he said.
Though fire is not unusual in California, the hot summers have "turbocharged" the conditions that cause fires to grow.
“We see fires growing from essentially nothing to a quarter of a million acres in one day," he explained. "And that’s because the conditions are ripe, and temperature plays a large role.”
“In a world without climate change, it still would have been a hot August; we still would have had some fires. But it’s clear that climate change has made things notably worse,” he added.
Lori Daniels, a forestry professor at the University of British Columbia, told the Associated Press that climate change has intensified fires on both sides of the border.
Warm and dry conditions make it easier for small fires started by lightening or human activity to grow and travel through forests. As a result, British Columbia endured its own record-breaking fires in 2017 and 2018.
“This is everywhere,” Daniels said. “We’re all experiencing extreme temperatures, extreme droughts, extreme fires driven by those droughts, and they are the hallmarks of climate change.”
Our rating: False
Based on our research, the claim that wildfires on the West Coast stop at the borders of Canada and Mexico is FALSE. Despite some maps that show only fires in the United States, both neighboring countries have seen fires in recent weeks. Scientists have confirmed that climate change has exacerbated the usual fire season into this month's crisis.
Our fact-check sources:
The Los Angeles Times, Sept. 11, Six of California’s largest fires in history ignited this year. Here’s what we know
The Associated Press, Sept. 11, Amid ashes, California governor fires away on climate change
USA TODAY, Sept. 11, Fact check: Oregon, Washington fires were not set by anti-fascist activists
Katherine Hayhoe, Sept. 13, Tweet
Government of Canada, National Wildland Fire Situation Report
Comisión Nacional Forestal, Sept. 9, Tweet
Comisión Nacional Forestal, Sept. 11, Tweet
The Los Angeles Times, Sept. 13, How climate change is fueling record-breaking California wildfires, heat and smog
The Associated Press, Sept. 15, Maps of wildfires ending at Canadian border only show US data
Thank you for supporting our journalism. You can subscribe to our print edition, ad-free app or electronic newspaper replica here.
Our fact check work is supported in part by a grant from Facebook.
This article originally appeared on USA TODAY: Fact check: Canada and Mexico are fighting wildfires, too