The Arctic is burning in a whole new way.
Nowadays, large fires are increasingly common in the Arctic. It is an issue that worries many scientists. This year, too, the fire season started two months earlier than usual. Moreover, the conflagrations stretched over an unprecedented large area. However, it is not only this size of the burning areas that is alarming. “We notice other trends,” says researcher Merritt Turetsky. “And they tell us how the fires in the Arctic are changing and what this means for our future climate.”
Things are going to get tough in the Arctic this year. Between January 1 and August 31, fires in the area already released more CO2 than in all of 2019. For example, between January 1 and August 31, 244 megatons of CO2 were released, while in 2019 raging fires in the same area were responsible for the emissions of such 181 megatons of CO2. It is assumed that the increase can be traced back to drought and higher temperatures and is therefore a direct result of the changing climate. According to researchers, this threatens to create a vicious circle, in which a changing climate leads to conditions that make fires more likely high in the north and the fires subsequently contribute to further climate change.
In their study, published in the journal Nature Geoscience, the researchers analyzed satellite data from the Russian Arctic to accurately map the surrounding fires. While wildfires over permafrost in Siberia south of the Arctic are not uncommon, the team found that particularly in 2019 and 2020, massive fires have raged in areas that don’t normally catch fire as quickly. “As a result,” said study leader Jessica McCarty, “Arctic fires are starting earlier in the season in landscapes previously considered fire resistant.”
It means that the Arctic is now burning in a whole new way. And in the study, the researchers uncovered two new features of the recent polar fires. The first can be grouped under the heading ‘zombie fires’. Those are actually fires from the previous year that smoldered in carbon-rich peat underground during the winter months and then flared up again at the surface in early spring. “We actually know little about the consequences of this in the Arctic,” notes Turetsky. “Except they could mean serious fires in one year pave the way for more fires next summer.”
Fire resistant vegetation
The second characteristic is the combustion of normally fire-resistant vegetation. While tundra in the far north is getting warmer and drier due to climate change, vegetation types that are typically not classified as combustible are starting to catch fire. Consider, for example, certain shrubs, grasses, mosses and peat. Normally wet landscapes – such as swamps and fens – also dry out more and more, making them easier to catch on fire.
These profound changes could have significant implications for the Arctic landscape, its inhabitants and the global climate, the researchers warn. More than half of the fires that raged in Siberia this year were located north of the Arctic Circle on permafrost with a lot of ground ice. This type of permafrost retains enormous amounts of carbon from old biomass. And when this permafrost thaws, it releases methane and carbon dioxide, transporting these greenhouse gases to the atmosphere, contributing to global warming. “Almost all of this year’s fires within the Arctic Circle took place on permafrost,” says researcher Thomas Smith. “And more than half of these fires are raging on old carbon-rich peat soils.” And that is alarming. “The record high temperatures and associated fires have the potential to turn this important carbon sink into a carbon source,” explains Smith. “This will further increase global warming.”
More locally, the abrupt thawing of icy permafrost fueled by forest fires causes subsidence, flooding, wells and craters and can sink large areas under lakes and swamps. And this not only disrupts the lives and livelihoods of Arctic residents, but can also allow greenhouse gases stored in the soil to find their way into the atmosphere.
The severity of the recent Arctic fires underscores the urgent need to better understand the changes taking place in the Arctic. In addition, new tools and approaches are needed to better measure the onset of fires and the size of an area ablaze. Models and remote sensing can help, but only when combined with local, specialized knowledge of where carbon, stored in peat or permafrost, is vulnerable to combustion and how environments change after disastrous conflagrations. “In monitoring the fires, we need global cooperation, investment and action,” argues McCarty. “We also need methods to control fires on permafrost or peat soils in the Arctic. There is no time to waste. ”
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