Warming – Permafrost, the time bomb for the climate

Warming – Permafrost, the time bomb for the climate
Warming – Permafrost, the time bomb for the climate

Posted27 October 2021, 08:26

Permafrost – soil that remains frozen permanently for two consecutive years – poses a threat if it continues to melt and release the greenhouse gases it contains.

Surrounded by snow-capped mountains, the Stordalen Plateau is a vast peat swamp, riddled with muddy ponds. A strange smell of rotten eggs disturbs the pure air of the Swedish Far North. The site is about ten kilometers from the small town of Abisko, where global warming is three times faster than elsewhere in the world.

Here, scientists scrutinize the melting of frozen subterranean soil, known as the geologic name of permafrost (or permafrost). When researcher Keith Larson walks over the wooden planks laid out in a network to circulate above the marshy ponds to do his tests, the structure sinks into the bog and bubbles emerge on the surface.

“Marsh gas”

Its characteristic odor comes from hydrogen sulphide, sometimes referred to as “swamp gas”. But it is another gas that escapes with it, odorless in its natural state, which alarms the scientific community: methane. Long locked in permafrost, greenhouse gases are released today.

Between methane (CH4) and carbon dioxide (CO2), permafrost contains some 1,700 billion tonnes of organic carbon, almost twice the amount of carbon already present in the atmosphere. Methane lasts 12 years in the atmosphere, compared to centuries for carbon dioxide, but it has a greenhouse effect 25 times more powerful than CO2. Scientists have warned: The melting of permafrost is a “time bomb” for the climate.

Between methane and carbon dioxide, permafrost contains some 1,700 billion tonnes of organic carbon.


Vicious circle

In the 1970s, “when researchers began to examine these terrains, these ponds did not exist,” says Keith Larson, coordinator for the Center for Research on the Impact of Global Warming at the Swedish University of Umea based at the Abisko Scientific Research Station.

“The odor of hydrogen sulfide, associated with the methane that escapes, they did not smell it at this point”, continues the researcher who to measure the depth of the so-called “active” layer of permafrost, the part which thaws in summer, push a metal bar into the ground.

Permafrost – soil that remains frozen permanently for two consecutive years – extends under a quarter of the land in the northern hemisphere. In Abisko, it is up to ten meters thick and dates back thousands of years. In Siberia, it can reach over a kilometer in depth and be hundreds of thousands of years old.

As temperatures rise, the permafrost begins to melt. Bacteria in the soil break down the biomass stored in frozen soil, resulting in emissions of carbon dioxide and methane, greenhouse gases which in turn accelerate global warming. A formidable vicious circle.

Point of no return ?

By 2100, if CO2 emissions are not reduced, permafrost could have “considerably” melted, warned scientists from the United Nations Intergovernmental Panel on Climate Change (IPCC).

The annual average temperature in the Arctic has risen by 3.1 degrees C for half a century, compared to 1 ° C for the planet as a whole, the Arctic Monitoring and Assessment Program warned in May ( Amap).

Could permafrost reach a climatic “tipping point”, this critical threshold beyond which the release of CO2 and methane is inevitable and the change of the ecosystem irreversible, according to the definition of the IPCC, with the risk of disrupting the whole planetary system?

The major problem is that the melting of the permafrost and the release of carbon will continue even if all human emissions cease immediately.

Many risks

The degradation of permafrost poses many risks for populations and threatens infrastructure such as water and sewer pipes, oil pipelines and chemical, biological and radioactive waste storage structures, noted in 2019 a report from the Russian Ministry of Justice. ‘Environment.

Last year, a fuel tank shattered when its foundation suddenly sank into the ground near Norilsk in Siberia, spilling 21,000 tonnes of diesel into nearby rivers. Norilsk Nickel then claimed that the plant’s structures had been weakened by the thaw of the permafrost.

Across the Arctic, melting permafrost could affect up to two-thirds of infrastructure by 2050, according to a draft report by IPCC experts on the impacts of warming obtained in June by AFP and which is to be published in 2022.


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