Nature offers one of the least comforting explanations for a mysterious hole in Siberia. It wasn’t from an asteroid or a rogue telephone-pole-installing crew. The 30-meter-wide crater was caused by methane – a flammable, stinky greenhouse gas – being released from melting permafrost:
Over the past 20 years, permafrost at a depth of 20 metres has warmed by about 2°C, driven by rising air temperatures, notes Hans-Wolfgang Hubberten, a geochemist at the Alfred Wegener Institute in Potsdam, Germany.
Hubberten speculates that a thick layer of ice on top of the soil at the Yamal crater site trapped methane released by thawing permafrost. “Gas pressure increased until it was high enough to push away the overlying layers in a powerful injection, forming the crater,” he says. Hubberten says that he has never before seen a crater similar to the Yamal crater in the Arctic.
Larry Hinzman, a permafrost hydrologist at the University of Alaska in Fairbanks and director of the International Arctic Research Center, says that such craters could become more common in permafrost areas as the region heats up.
One of the key things here: no-one knows how deep it is yet. The rim is melting and falling in, so no-one can get close enough to measure. And smaller “powerful injection” holes have been found by local reindeer herders.