Global wildfire activity will increase in coming years


As global warming warms the air and land, dries out trees and other plants, people around the world must revise their expectations of where, when and how long wildfires will last, warns a new global report on forest fires published today.

In a quick look, the scientists who authored the United Nations Environment Program report project a global increase in extreme fires of up to 14% by 2030, 30% by the end of 2050 and 50% d end of the century.

The rapidly changing fire conditions were the “driving reason for producing the analysis we carried out”, said Andrew Sullivan, of the Commonwealth Scientific and Industrial Research Organization in Canberra, Australia, one of the main writers of the report.

“Eliminating the risk of wildfires is not possible, but much can be done to manage and reduce the risks they pose,” he said. “Integrated wildfire management, taking into account social and environmental dimensions and the management of traditional and indigenous lands, is essential to adapt to current and future wildfire risks.

Given the visibly imminent threat, UN experts said, governments must shift gears drastically from responding to fires as they occur to investing in preparedness and response. resilience, which will be less costly in the long run. Local and indigenous knowledge can lead the way in helping people relearn how to live with fire.

The report comes after two years in which extreme wildfires have burned almost nonstop in the northern and southern hemispheres, with many fires reaching unprecedented scales and burning in unexpected seasons, such as the recent Marshall Fire that has destroyed approximately 1,000 suburban homes near Boulder, Colorado in late December. And as 2022 began, large and intense fires have ravaged parts of Argentina and Chileincluding the forests of Patagonia which have rarely seen large fires.

Extreme wildfires are not only a threat to human lives and communities. They also destroy existing landscapes and ecosystems. The researchers estimated that the 2019-2020 Australian wildfires killed or injured between 1 billion and 3 billion animalsand some forests that have recently burned will only regrow as dilapidated scrub because the climate is too hot and dry to support seedlings, and some areas of burning scrub are at risk of turning into grassland that burns even more frequently.

The frequency of fires is a critical factor in whether certain ecosystems can fully regenerate, said cam walkera campaign coordinator for Friends of the Earth Australia.

“Parts of the Australian Alps have been burned three times in a decade or so, well beyond normal fire cycles, with impacts on species that regrow,” he said. Alpine ash is particularly vulnerable because although it can regenerate after a fire, it takes about 20 years before it sets seed.

“The increased frequency of fires means that much of the mountain and alpine ash communities are susceptible to collapse,” he said. “Under current climate scenarios, there is little doubt that these forest systems will be further impacted in the second half of the century.”

Ensuring the survival of these systems is a daunting task, because “the only way to do so is to protect them from fire for at least 100 years so that they can regrow into the less fire-prone older growth phase of their life cycle. life,” he said. noted. “This has huge implications for firefighting due to the additional air and ground resources we would need to achieve this goal.”

Forest fires are a direct threat to the climate

The new UN report reinforces previous findings that the upsurge in wildfires also directly threatens the climate with increased emissions of global warming carbon dioxide. In some major fire years, scientists have found that emissions from fires can account for up to “40% of total annual average global carbon emissions from all fossil fuels”.

The report highlights that expanding fire activity in the Arctic, which is currently warming three times faster than the global average, will compound this threat as moist boreal forests and tundra dry out and become vulnerable. to ignition caused by lightning, which are also increasing in the Arctic.

And the global warming effect of wildfire emissions may still be grossly underestimated, at least for some types of fires. A study published on February 8 suggested that emissions from wildfires in peatlands in 2019 and 2020, with organic and flammable soil, may have been 200-300% higher than originally calculated.

Another one study published on February 16 in Nature showed that wildfire behavior also crosses other critical thresholds that will lead to more severe fires. The researchers, led by scientists from the Cooperative Environmental Science Research Institute Earth Laboratory at the University of Colorado, Boulder found a huge increase in the number of “burning nights”, when conditions remained conducive to burning at night. In today’s climate, there are 11 more flammable nights each year in the western United States than just 40 years ago, an increase of 45%.

“Nighttime is the critical time to slow an accelerating fire, and nighttime wildfire brakes fail,” said lead author Jennifer Balch. “With continued overnight warming, we expect to see more, more intense, faster and larger out-of-control wildfires,” she said.

“This means firefighters no longer have the night breaks they used to have. They have to fight the flames 24 hours a day, 7 days a week.”

The UN report reinforces the urgency for people in the western United States to prepare for unexpected fires in unusual places, said Jean Abatzogloufire and climate researcher at the University of California, Merced.

“We have seen, and expect to see, more fires due to a warming and drying climate in forests that historically have had little fire,” he said. This includes higher elevation forest types such as spruce and fir areas, where most of Colorado’s major ski resorts are located, but also some of the wettest forests, such as California’s coast redwoods and Cascades, he added.

“These areas are generally too wet for widespread fire in the vast majority of years, but with longer fire seasons and increased fuel drying, there is more opportunity for these landscapes to become flammable and fire-carrying. .”

Perhaps the most ominous warning came from another Colorado researcher who studied chemical traces in ancient rocks to find that wildfires expanded dramatically around 94 million years ago when the Earth was warmer, with more oxygen in the atmosphere.

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Over a period of 100,000 years at that time, fires may have burned up to 30 or 40 percent of the world’s forests. While today’s fires are exacerbated by dry conditions, wildfires during this period have increased even in humid regions due to changes in global climate, said geologist Garret Boudinot, lead author of the 2020 study paper in nature geoscience.

The research suggests that the increase in fires may have been caused by an increase in oxygen in the atmosphere. Large amounts of carbon dioxide in the atmosphere, much like what Earth is expected to experience by 2100, started the cycle.

He explained that the Earth is currently undergoing a similar transformation, with a buildup of carbon dioxide in the atmosphere and a buildup of nutrients in the ocean, a process that ends in a high concentration of oxygen in the atmosphere, ideal for fueling fires.

“This underscores that the emission of carbon dioxide into the atmosphere and nutrients into the ocean does not just potentially increase global temperatures,” he said. “This has significant impacts on the fundamental biogeochemistry, or ecology, of the planet. One of the consequences of having more oxygen in the atmosphere is that it is easier to burn fires. is the same reason you blow on embers to stoke a fire.


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