thermokarst
THER-moh-karst
The irregular, pitted, hummocked terrain that forms when ice-rich permafrost thaws and the ground collapses into the voids left behind. Thermokarst landscapes are full of subsidence pits, slumping banks, tilting trees ("drunken forests"), and shallow lakes that appear, expand, drain, and disappear as the ice beneath them melts. It is the landscape of permafrost coming undone.
Etymology
From thermo- (heat) + karst (the German/Serbo-Croat term for limestone dissolution terrain). The analogy is to limestone karst — both produce pitted, collapsed landscapes — but the mechanism is thermal rather than chemical. The ice melts instead of the rock dissolving.
Notes
Thermokarst is accelerating across the Arctic as temperatures rise. It is one of the most visible signatures of climate change on the land surface.
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