Arctic Wildfires
Scientists expect exponential rise in fires from subtle temperature changes.
Wildfires in the Arctic are releasing enormous amounts of carbon that was previously stored in peatlands, further increasing global warming, according to a new study.
Satellite data shows that 4.7 million hectares of land, an area about two times the size of Vermont, was burned in the Siberian Arctic in 2019 and 2020. This accounted for 44% of the total area burned in the region over the last 40 years, according to research published in the journal Science.
“Given the strong correlation between average temperatures and area burned, we anticipate that future warming will result in wildfires similar to those in 2020 by the end of the century,” wrote Adría Descals in an email, the lead author of the study.
The Arctic is one of the most rapidly warming places on earth. Scientists expect that subtle increases in temperature are going to lead to an exponential rise in total area burned.
The Arctic circle encompasses ecosystems from boreal, or evergreen forests, to peatlands. According to the International Peatland Society, peatlands are wetland ecosystems where plant matter is prevented from fully decomposing because of waterlogged conditions. Peat is the top layer of soil in these areas.
Peatland ecosystems are distributed throughout the northern hemisphere in Europe, North America and Russia. Arctic peatlands occur at the northern most part of this territory. They are mostly frozen and stay frozen throughout the year. They can also be referred to as permafrost peatlands.
“Permafrost peatlands contain about twice as much carbon as the atmosphere,” wrote Descals.
These ecosystems gather and store more carbon than any other on the planet. Cold temperatures in the region mean a shorter growth season and lower decomposition rates. This means that larger amounts of carbon get stored in the soil.
According to the study published in Science, Arctic and Subarctic wildfires do happen. These regions burn at a relatively low frequency compared to other ecosystems.
“On average they burn once every 70 or 100 years, whereas a lot of the grasslands for instance in Africa burn every year,” said Michelle Mack, an ecosystems ecologist and regents’ professor at Northern Arizona University who co-authored a related perspective on the study.
With global temperatures warming, Arctic wildfires’ frequency, size and intensity are expected to increase.
Researchers assessed the annual burned Siberian Arctic because it’s where the most burnings occur above the Arctic circle and the frequency of the fires seemed to be increasing.
Scientists looked at six different satellite maps of the burned areas ranging from the years 1982 – 2020. They found that almost 13 million hectares of land were burned in this region and the Siberian Arctic accounted for 71% of it.
From the maps they noticed that over 9 million hectares of the total land burned occurred in the years 2019 and 2020. That means that over 40% of the total burned area occurred within the last three years.
“There are areas that we’ve documented that burned for the first time in 3,000 years,” said Mack
Scientists investigated 10 factors that could contribute to the likelihood of fire that ranged from surface temperature to precipitation. They also looked at the length of the growing season and the amount of vegetation being grown.
What researchers noticed is that the amount of moisture in the air has been decreasing while the air temperature, amount of vegetation and length of the growing season have all been steadily increasing
“Arctic warming has a dual effect on the fire regime; it increases the number of lightning -caused fires and the susceptibility of vegetation to burning,” wrote Descals.
A warmer atmosphere causes more lightning and vegetation, which leads to a higher likelihood of fires. More fires release more carbon dioxide into the atmosphere, which causes more warming. Scientists call this a positive feedback loop.
Descals describes it as a “vicious circle.”
The fires are burning vegetation which releases carbon into the atmosphere as well as burning the peat. When peat gets burned, it thaws parts of the permafrost underneath it. The permafrost then releases carbon in the form of decomposition. The release of carbon is happening on multiple fronts.
“The other thing about these Arctic fires is that the soil is burning,” said Mack. “It’s all this organic material that the lower 48 (states) ecosystems don’t really have.”
Scientists are beginning to think that these Arctic peatlands and forests are changing from carbon sinks into carbon sources. Carbon sinks are ecosystems that take in more carbon than they release.
Most of the Arctic has what scientists call “legacy carbon” which means that the carbon is very old in these ecosystems. It has been layering and freezing repeatedly in the permafrost but now that the permafrost is thawing, more carbon is starting to get released.
“Northern peatlands currently account for an annual carbon sink of 100 million metric tons,” according to the related article written by Mack.
But fire is burning deeper into these soils, releasing carbon and thawing more permafrost, which releases more carbon.
The wildfires that occurred in the Siberian Arctic in 2019 and 2020 released 150 million metric tons of carbon into the atmosphere. That amount of carbon would be equivalent to powering almost 19 million homes for a year.
These fires aren’t just burning vast expanses of uninhabited land either. There are many communities of people that live in these regions.
Most of these communities are rural and the people in them depend on natural resources. Not only are the fires damaging the atmosphere and in turn the planet, but they are also hurting the communities of the people that rely on these ecosystems to support their way of life.
“There really are people that live in these forests that have lived there for thousands of years, whose cultures depend on them, and more fire is a very real stress for these communities,” said Mack
Scientists agree that the main cause of these Arctic fires is from carbon dioxide emissions from human use of fossil fuels.
“It is imperative to reduce anthropogenic greenhouse gas emissions to prevent this vicious circle from accelerating in the coming decades,” wrote Descals.
Mack has a similar view.
“I think we’re not going to stop these fires but it’s one more piece to bring forward for policy makers or just the general public to think about,” said Mack. “We have to regulate the emissions that we have control over.”