Global warming is causing growing fires in arctic Siberia, and these threaten to release huge amounts of carbon into the atmosphere over the next few decades. trapped in the ground, a new study warned on Thursday.

The researchers fear that a threshold will soon be reached, beyond which small increases in temperature will cause an exponential increase in fires in this region.

In just two years, in 2019 and 2020, fires in this remote area of ​​the globe have ravaged an area equivalent to almost half of that burned over the past 40 years, revealed this study published in the journal Science.

And they released some 150 million tons of carbon into the atmosphere, according to the researchers' estimates, thus contributing themselves in return to global warming, in a veritable vicious circle.

4 times faster heating

The Arctic, above the polar circle, is warming four times faster than the rest of the planet.

“It is this climatic amplification that causes abnormal fire activity,” said David Gaveau, one of the authors of this work.

The researchers focused on an area five and a half times the size of France, observing through satellite images the areas burned each year between 1982 and 2020.

In 2020, more than 2.5 million hectares were ravaged by the flames, they found, releasing in CO2 equivalent the amount emitted by Spain in a year.

But that year, the Siberian summer was on average three times hotter than in 1980. The Russian city of Verkhoyansk had recorded in June 38°C, the record for the Arctic.

The average air temperature in summer (June to August) only exceeded 10°C four times over the period studied: in 2001, then 2018, 2019 and 2020. However, these were the four years with the most fires.

Researchers fear that this 10°C threshold will mark a “breaking point”, which will be exceeded more and more often, explained David Gaveau.

“The system gets carried away, and for a small increase in degrees beyond 10°C, all of a sudden, we have a lot of fires.

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Permafrost thaw

Many of these areas of Siberia, Russia are peat bogs, swampy areas that may be covered in tundra, and they absorb carbon.

Fires thus have the effect of releasing it into the atmosphere in the form of CO2.

Fires also damage permafrost – permanently frozen ground, or permafrost in English –, which then releases even more carbon into the atmosphere, sometimes trapped in the ice for centuries or even millennia.

“That means that carbon sinks are transformed into carbon sources,” explains David Gaveau.

“If there continue to be fires every year, the soil will be in increasingly poor condition, so there will be more and more emissions from these soils, and that is what is very worrying.

The amount of CO2 released in 2020 was "high", but "it could be even more catastrophic than that in the future", warns the researcher, whose company The Tree map studies deforestation and forest fires.

Rising temperatures have an impact in several ways: more water vapor rises in the atmosphere, causing more thunderstorms, and therefore more lightning, igniting fires.

Vegetation grows more, providing more fuel, and it also transpires more, causing drying out.

Different Scenarios

For the future, the study analyzed two possible scenarios.

In the first, nothing is being done to combat climate change, and temperatures continue to rise steadily.

In this case, fires of the same magnitude as in 2020 would become possible each year.

In the second scenario, greenhouse gas concentrations stabilize and temperatures plateau by the second half of the century.

Then, fires like those of 2020 would occur "on average every 10 years", explained Adria Descals Ferrando, lead author of the study.

Be that as it may, “summers with fires like 2020 will be more and more frequent from 2050 and beyond”, summed up David Gaveau.

A few days before the opening of the UN climate conference, COP27, the researcher hopes that world leaders will come to an agreement on progress.

"The most important thing of all is to stop using fossil fuels that emit CO2," he said.

Because “what scientists fear is that one day we will have reached such a breaking point that the planet will become uninhabitable for many people.

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  • Planet

  • Siberia

  • Arctic

  • Carbon

  • CO2

  • Global warming