"Soaring temperatures are rapidly thawing permafrost, leading to huge sinkholes called thermokarst. Northern fires are making the situation even worse."
"A perfect storm is ravaging the Arctic—literally. As the world warms, more lightning systems are igniting more peat fires. They burn through ancient buried plant material and release great plumes of greenhouse gases, which further warm the planet. At the same time, as plant species march north thanks to a more hospitable climate, the Arctic is greening. That darkens the landscape and absorbs more of the sun’s energy, further heating the region. It also provides more fuel to burn; dried plants above ground ignite more readily than permafrost, which is made from frozen dirt or sand or gravel mixed with dead plants. But permafrost is now thawing so rapidly that it’s creating massive sinkholes in the earth, up to 100 feet wide and 10 feet deep, a process known as thermokarst.
New research shows how wildfires are exacerbating this land-gouging in north Alaska. After analyzing satellite and aircraft imagery going back to the 1950s, scientists calculated that thermokarst formation has accelerated by 60 percent since then. In the past 70 years, wildfires have burned 3 percent of the landscape but are responsible for 10 percent of thermokarst formation.
“We found that after wildfire activity, the rate in which thermokarst occurs on the landscape is higher for upwards of eight decades,” says plant biologist Mark Lara of the University of Illinois at Urbana-Champaign, coauthor of a paper describing the research published in December in the journal One Earth. The cratering creates pits of melted ice and organic matter, which absorb far more solar energy than snow. “If you follow those pits over years to decades, they start to grow and keep growing and getting larger and larger and larger over time. And they all stemmed from that initial small depression after a fire disturbed the tundra,” he continues."