‘Toxic surprise’ lurking in melting permafrost in the Arctic

A toxic risk that has been previously underestimated lurks in the melting permafrost of the Arctic – in the form of up to 20,000 contaminated sites.

The sites include pollutants such as radioactive waste – and lakes into which toxic waste was poured intentionally, in the belief the permafrost would never melt.

When the ground thaws, thanks to climate change, pollutants can be released as industrial sites collapse - and this could pose a serious risk.

The Arctic is full of oil fields and pipelines, mines and various other industrial activities, built on a foundation once considered to be particularly stable and reliable: permafrost.

Moritz Langer from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), said: "Traditionally, it's also been considered a natural barrier that prevents the spread of pollutants.

“Consequently, industrial waste from defunct or active facilities was often simply left on-site, instead of investing the considerable effort and expense needed to remove it."

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During the Cold War, over the decades this led to micro-dumps full of toxic sludge from oil and gas exploration, stockpiles of mining debris, abandoned military installations, and lakes in which pollutants were intentionally poured.

Guido Grosse, who heads the AWI's Permafrost Research Section said: "In many cases, the assumption was that the permafrost would reliably and permanently seal off these toxic substances, which meant there was no need for costly disposal efforts.

"Today, this industrial legacy still lies buried in the permafrost or on its surface. The substances involved range from toxic diesel fuel to heavy metals and even radioactive waste."

But as climate change progresses, this "sleeping giant" could soon become an acute threat.

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The permafrost regions are warming between twice as fast and four times as fast as the rest of the world, the frozen soil is increasingly thawing.

Contaminants that have accumulated in the Arctic over decades can be released, spreading across larger regions.

In addition, thawing permafrost becomes more and more unstable, which can lead to further contamination.

When the ground collapses, it can damage pipelines, chemical stockpiles and depots.

Just how real this risk already is can be seen in a major incident from May 2020 near the industrial city Norilsk in northern Siberia, where a destabilised storage tank released 17,000 metric tons of diesel, which polluted the surrounding rivers, lakes and tundra.

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"Incidents like this could easily become more frequent in the future," said Langer, who added that more research is needed to assess the true extent of the risk.

"But without more extensive data, these findings should be considered a rather conservative estimate. The true scale of the problem could be even greater."

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