Researchers with the U.S. Geological Survey and McGill University have discovered new permafrost forming near Twelvemile Lake in Alaska. The shrinking Arctic lake, and others like it, have been getting smaller in the past few decades.
The lake’s smaller size, with water levels 15 feet lower than 30 years ago, has allowed bands of willow shrubs to grow on its expanding banks, adding shade that has cooled and dried the ground there. Scientists say these cooler soils are fostering the expansion of permafrost beneath them.
The researchers were initially hopeful for the findings, given the prospect of recovering permafrost in areas of the Arctic where it had been lost. But then they considered their findings alongside climate model predictions.
Within about 90 years, if current climate trends continue, all of the new permafrost forming around Twelvemile Lake and others like it will be lost, they found. Though the newly frozen ground may be trapping greenhouse gases like carbon and methane now, it will likely eventually thaw and release them.
Full results of the study are available in the journal Geophysical Research Letters.