Two forces against one island
The researchers discovered that there are two different processes affecting the small island in the Laptev Sea and causing its ice cliffs to crumble. As Günther explains, “First of all, the permafrost on the cliffs is completely bare, which means it’s basically defenceless when it comes to rising air temperatures. So it’s thawing faster here, and as a result, the land mass continues to recede.” Secondly, the waters of the sea and the Lena River are gnawing away at Muostakh’s frozen subsurface. “In the past, a thick layer of sea ice protected the coasts from erosion practically year-round. But in the past three years alone, the number of ice-free days per year has risen considerably – an average of two weeks more than 20 years ago,” says Dr Paul Overduin, an AWI specialist for submarine permafrost, which Muostakh is surrounded by.
The two additional ice-free weeks and rising air temperatures also pose another threat for the island: until a few years ago, the thawing process and periods of open water came at different times of year: the ground thawed throughout the summer before slowly beginning to refreeze in late August, while the sea ice cover only receded in the late summer months and returned in the early autumn. Today these processes are increasingly overlapping. “That’s bad news for Muostakh, because taken together, the two processes are far more powerful than they are separately. And they’re extremely effective when it comes to accelerating the island’s erosion,” explains Frank Günther.