A landmark United Nations report has concluded that the risk of devastating wildfires around the world will surge in coming decades as climate change further intensifies what the report described as a “global wildfire crisis.”
The scientific assessment is the first by the organization’s environmental authority to evaluate wildfire risks worldwide. It was inspired by a string of deadly blazes around the globe in recent years, burning the American West, vast stretches of Australia and even the Arctic.
The images from those fires — cities glowing under orange skies, smoke billowing around tourist havens and heritage sites, woodland animals badly injured and killed — have become grim icons of this era of unsettled relations between humankind and nature.
“The heating of the planet is turning landscapes into tinderboxes,” said the report, which was published on Wednesday by the United Nations Environment Program.
The report, produced by more than 50 researchers from six continents, estimated that the risk worldwide of highly devastating fires could increase by up to 57 percent by the end of the century, primarily because of climate change. The risks will not be distributed equally: Some regions are likely to see more fire activity, while others may experience less.
It is a stark warning about the increased heat and dryness that human-caused global warming is bringing about. Nations and localities need to prepare better for the dangers, the report’s authors said.
“There isn’t the right attention to fire from governments,” said Glynis Humphrey, a fire expert at the University of Cape Town and an author of the new report. More societies worldwide are learning the value of prescribed burns and other methods of preventing wildfires from raging out of control, she said. Yet public spending in developed nations is still heavily skewed toward firefighting instead of forest management.
In some regions with long histories of brush fires, such as eastern Australia and the western United States and Canada, they have become more intense over the last decade and are ravaging larger areas, the report found. But uncontrolled burning is also starting to occur in places where it had not been common before, such as Russia, northern India and Tibet. In parts of the savannas of sub-Saharan Africa, by contrast, fire activity has declined over the past two decades, partly because drought has killed off more grass.
While climate change is giving rise to more of the record warmth and dryness that have contributed to recent episodes of severe burning, the overall effect on fire risks is complex and can vary from place to place.
Researchers have determined that the extreme heat wave in the Pacific Northwest last year almost certainly would not have occurred without planetary warming caused by greenhouse-gas emissions. Scientists have also found the fingerprints of climate change on brush fires in Australia and extreme heat and burning in Siberia.
But hot weather and weak rainfall can also decrease the amount of vegetation that is available to feed fires. In other places, the decreased humidity can make vegetation more flammable, helping fires spread more easily.
After taking all these factors into account, the report still forecasts a significant increase in the global risk of extraordinary wildfires, even if nations manage to limit emissions of heat-trapping gases.
In a moderate scenario for global warming, the likelihood of extreme, catastrophic fires could increase by up to a third by 2050 and up to 52 percent by 2100, the report estimates. If emissions are not curbed and the planet heats up more, wildfire risks could rise by up to 57 percent by the end of the century.
The increase in burning is projected to be especially large in places including the Arctic, said Douglas I. Kelley, a researcher at the U.K. Center for Ecology & Hydrology who conducted the data analysis for the report. The northern reaches of Russia and North America are already warming much more quickly than the rest of the globe. The intense Arctic fires of 2020 released more polluting gases into the atmosphere that June than in any other month in 18 years of data collection.
In more temperate regions of the United States and Asia, Dr. Kelley said, wildfires could increase as emissions rise because the higher amount of carbon dioxide in the air helps plants grow, resulting in more vegetation to fuel blazes.
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The prolonged drought in the American West — the region’s worst, scientists say, in at least 1,200 years — has been helping to spark wildfires earlier in the year. Forecasters are expecting the warmth and dryness to continue into this spring and beyond.
The U.N. report urges governments to become more proactive about fire hazards. Of every dollar spent in the United States on managing wildfires, almost 60 cents goes toward immediate firefighting responses, according to research cited in the report. Much less is spent on reducing fire risks in advance and helping communities recover in ways that could make them more resilient.
Peter Moore, a fire management consultant with the United Nations Food and Agriculture Organization and an author of the report, said more countries could learn from Portugal, which drew up an ambitious national fire plan after two blazes killed more than 100 people in 2017. Decades of economic development there had caused a decrease in farmland and an expansion of poorly managed forests, making the landscape highly flammable.
“So when the wrong weather turned up, and then a series of ignitions happened, they had a series of dramatic and catastrophic fire events,” Dr. Moore said. In eastern Australia, western North America, Chile and elsewhere, he said, “those same conditions are starting to occur.”
Not all human development adds to fire risks. In the tropical grasslands of Africa, population density has increased, and farmers have converted more of the area into cropland and pasture. That has fragmented the savannas, making it harder for wildfires to spread. Researchers have used satellite data to estimate that, despite global warming, large decreases in Africa helped the total amount of burned land worldwide fall by a quarter between 1998 and 2015.
Many fires in Africa are set deliberately to clear away vegetation and avert wildfires that would be more severe and less controllable, said Dr. Humphrey of the University of Cape Town. Communities in many places have been managing the land this way for centuries, and the U.N. report calls for such traditional knowledge to be better integrated into fire policies.
Dr. Humphrey said more governments needed to discover, or rediscover, what fire actually is: “something really critical for our planet, but that also needs to be managed.”