A “series of anomalously warm summers” has dramatically accelerated melting rates at three sites despite average annual ground temperatures remaining low. Ponds and hillocks have formed as a result.
It had been thought that the permafrost – ground that remains frozen for at least two years – would remain until at least 2090.
But the study found thawing levels were above 150 to 240 per cent above historic levels.
Researchers called this a “truly remarkable amount”.
Mould Bay on Prince Patrick Island was the worst-affected site, according to the study, published on the journal Geophysical Research Letters.
There, permafrost thawing levels were 240 per cent higher than historic levels and the ground sank 90 cm over the course of the study which ran for over 12 years, between 2003 and 2016.
Researchers also recorded thawing at depths not expected until air temperatures rose to levels that the UN Intergovernmental Panel on Climate Change (IPCC) predicted it would reach in 2090.