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This is well above normal levels for this part of the year and surpasses the emissions increase from major fires in the American West in 2020. Only California fires were produced. more than 100 million tons Carbon dioxide, which was already enough last year to more than cancel out the wider region’s annual emissions reductions.

“Continuous but slow declines [greenhouse gases] “It pales in comparison to those from wildfires,” says Oriana Chegwidden, a climate scientist at CarbonPlan.

Massive forest fires burning millions of acres in Siberia also clog the sky and release across eastern Russia tens of millions of tons of emissions, Copernicus reported earlier this month.

Fires and forest emissions are expected to increase in many parts of the world, with climate change accelerating in the coming decades, creating hot and often dry conditions that turn trees and plants into kava.

The fire risk, defined as the probability of a region experiencing a moderate to high-severity fire in any given year, could quadruple across the United States by 2090, even in scenarios where emissions fall significantly in the coming years, according to one study. last study By researchers at the University of Utah and CarbonPlan. With uncontrolled emissions, the US fire risk could be 14 times higher by the end of the century.

Emissions from fires “are already bad and will only get worse,” says Chegwidden, one of the study’s lead authors.

“Very unlucky”

Over longer periods of time, the emissions of increased wildfires and their impact on the climate will depend on how fast forests grow and how much they retract carbon, or whether they do so. This in turn depends on dominant trees, the severity of fires and how much local climatic conditions have changed since the forest took root.

While studying for her doctorate in the early 2010s, Camille Stevens-Rumann spent the summer and spring hiking in the mountain forests of Idaho’s Frank Church-Wilderness of No Return and studying the consequences of fires.

He recorded where and when coniferous forests began to return, where they did not, and where opportunistic invasive species such as cheatgrass took over the landscape.

In 2018 study In Ecology Letters, he and his co-authors concluded that burning trees along the Rocky Mountains were in much more trouble this century as the region became hotter and drier than at the end of the previous one. Dry conifer forests, already swinging at the edge of survival, were much more likely to turn into grasses and shrubs, which often absorb and store far less carbon.

This can be healthy up to a point and create fire breaks that reduce the damage of future fires, says Stevens-Rumann, assistant professor of forest and rangeland management at Colorado State University. It could also help somewhat offset the US history of aggressively extinguishing fires in many forests, which allows fuel to accumulate and also increases the likelihood of large flames when ignited.

But he says his findings are “very ominous,” given the projections for the massive fires we’re already seeing and increasingly hot, dry conditions in the American west.

Other research has indicated that these pressures could begin to fundamentally transform western US forests in the coming decades, damaging or destroying biodiversity, water, wildlife habitat and carbon storage resources.

Fires, droughts, insect infestations and changing climatic conditions will turn large portions of California’s forests into undergrowth. modeling work published last week in AGU Advances. Tree losses can be particularly steep in dense Douglas fir and coastal redwood forests along the Northern California coast and at the foot of the Sierra Nevada mountain range.

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Altogether, the government would lose about 9% of the carbon stored in trees and plants above ground by the end of this century, and more than 16% in a future world where these continue to rise, in a scenario where we stabilize emissions this century. .

Among other effects, this would clearly complicate the state’s reliance on its land to capture and store carbon through its own territory. forestry offsets program and other climate efforts, study notes. California is trying to be carbon neutral by 2045.

Meanwhile, the medium to high emissions scenarios are “21. It creates a real possibility” of converting Yellowstone forests to non-forest vegetation by the middle of the century, as increasingly widespread and large fires will make it increasingly difficult for trees to regrow. , 2011 study It resulted in the Proceedings of the National Academy of Sciences.

global picture

The net impact of climate change on fires, and the net impact of fires on climate change, is much more complex globally.

Fires directly contribute to climate change by releasing rich carbon stored in soils and peatlands, as well as emissions from trees. They can also produce black carbon that can eventually settle on glaciers and ice sheets where it absorbs heat. This accelerates ice loss and rising ocean levels.

But fires can also provide negative climate feedback. While the smoke from the Western bushfires that has reached the East Coast in recent days is dire for human health, carries aerosols reflects some heat back into space. Similarly, fires in boreal forests In Canada, Alaska and Russia, it could make room for snow, which is much more reflective than the forests it replaces, and offset the warming effect of the emissions released.

Different parts of the world also push and pull in different ways.

Climate change is exacerbating wildfires in many of the world’s forested areas, says James Randerson, professor of earth system science at the University of California at Irvine and co-author of the AGU paper.

But the total area burned by fires worldwide actually going downprimarily thanks to reductions in the savannas and grasslands of the tropics. Among other factors, sprawling farms and roads are breaking up the landscape in developing regions of Africa, Asia and South America, serving as a break for these fires. Meanwhile, growing herds of animals are ingesting fuel.

Overall, global emissions from fires are about one-fifth of those from fossil fuels. not rise sharply yet. But when you include fires, deforestation and logging, the overall emissions from forests clearly increase. According to one study, tons that were less than 5 billion tons in 2001 increased to over 10 billion tons in 2019. Nature Climate Change paper In January.

less fuel to burn

As warming continues in the coming decades, climate change itself will affect different areas in different ways. While many regions will become warmer, drier and more susceptible to wildfires, some cooler parts of the world will become more conducive to forest growth, such as high parts of high mountains and parts of the Arctic tundra, Randerson says.

Global warming may also reach a point where it begins to reduce certain risks. By the end of the century, fires could begin to subside if the Sierra Nevada and other areas in Yellowstone, California, lose as much of their forest as research suggests. This is because there will be less or less flammable fuel to be burned.

Doug Morton, head of the biospheric sciences lab at NASA’s Goddard Space, said it’s difficult to make reliable predictions about global forest and fire emissions in the coming decades because there are so many competing variables and unknowns, especially including what actions people will decide to take. Flight Center.