Menopausal Mother Nature

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Arctic Warming Is Causing a 60-Fold Increase in Permafrost Landslides – by Dr Antoni G. Lewkowicz

Typical vegetation cover in (A) active, (B) stabilised and (C) undisturbed zones in and around retrogressive thaw slumps. (Credit: Click to Enlarge.

One of the principal concerns of a warming Arctic is the thawing of carbon-rich permafrost, which could release CO2 and methane into the atmosphere and accelerate climate change.

However, the thawing of these perennially frozen soils also risks making a mark on the land surface itself, causing landslides known as “retrogressive thaw slumps”.

When I first studied retrogressive thaw slumps on Banks Island in the Canadian Arctic in the 1980s, global climate models were in their infancy and the magnitude of human-caused climate warming was still being understood.

We now have a much better idea of the scale of future warming and its amplification in the Arctic.  And in our new study, published in Nature Communications, my co-author Dr Robert Way and I show how warmer summers are causing more landslides, which is having a profound impact on the Arctic landscape and ecosystem.

A retrogressive thaw slump (RTS) is a landslide that can occur only in permafrost areas.  It develops when the ice within the soil melts rapidly, leaving the soil weakened and unstable.  Where this happens on a slope, the instability can result in a landslide.

We call these landslides “retrogressive” because the headscarp – the steep exposed soil face at the top of the landslide – progressively retreats upslope after the initial slumping.  They are “thaw” slumps because they are caused by the thawing of ice in the permafrost.  And they are “slumps” because that’s the term most commonly used for bowl-shaped landslides.

Read more at Arctic Warming Is Causing a 60-Fold Increase in Permafrost Landslides