Scientists have pointed to the most probable cause of the massive hole spotted by a helicopter pilot in the Siberian region of Yamal earlier this month in a news report by Nature. According to researchers in Russia, a large build-up of methane gas was the likely culprit.
Conjecture has run wild since the discovery. Pingos, extraterrestrials, explosions of missiles, and a meteorite have all been suggested as the source of this baffling hole in the ground. However, scientists are pointing to a much more likely culprit: that a massive bubble of methane was likely released from the ground as the permafrost in the area thawed.
In mid-July, measurements were taken in and around the crater itself to determine the cause. Scientists are pointing to methane because the air in the bottom of the hole contained very high concentrations of the gas — 9.6%. The normal methane concentration of air is 0.000179%.
Methane gas (which is the kind of gas we use to heat our homes and cook with) is formed naturally in the ground as organic matter decomposes. Thousands of years of plants and animals are buried in the frozen Arctic ground, which keeps the organic matter preserved. However, as that cold ground melts, the matter begins to decay, and tiny microbes help the process along. This is what releases methane into the ground. Methane can then build up into pockets and pools, and the only thing keeping it below the surface is the frozen layer of ground above it.
Scientists think that as the permafrost melted, either from the exceptionally warm summers of 2012 and 2013, or the long-term melting in the region, the pressure building up in the methane bubble was large enough to push through the surface, ejecting the ground and creating a massive hole.
Another smaller hole almost identical to the first was discovered days later less than 20 miles away. Farmers in Yamal (which means “end of the earth”) discovered the second hole while herding reindeer.
It’s possible that as the planet warms, these huge methane ejections will become more frequent. As permafrost melts, it could allow methane that was once trapped below the ice to escape into the atmosphere. This will not only speed Earth’s rate of warming (methane is a more potent greenhouse gas than carbon dioxide), but it could also pose a danger to surrounding communities. “If [a release] happens at the Bovanenkovskoye gas field that is only 30 km away, it could lead to an accident, and the same if it happens in a village,” says Andrei Plekhanov, an archaeologist at the Scientific Centre of Arctic Studies in Salekhard, Russia.
Besides the obvious threat to the local communities, Marina Leibman, chief scientist at the Earth Cryosphere Institute of the Siberian Branch of the Russian Academy of Sciences, thinks these events are commonplace and not a cause for concern. In an interview with The New York Times’ Andrew Revkin, she stresses that it’s hard to assume that global warming is causing this permafrost melt, nor that future warming across the globe will also lead to more melting in Siberia.
However, it’s difficult to not be concerned about the threat of permafrost melting given the unknowns. Scientists currently do not have a good handle on exactly how much greenhouse gas could be trapped in the Arctic permafrost, though they do know it’s a lot. It’s possible, as the earth continues to warm, that the Arctic will reach a tipping point and become yet another, massive source of greenhouse gas seeping into the atmosphere.
In the meantime, the mystery hole, which Leibman estimates is about a year old given the fresh greenery surrounding it, will likely turn into another lake dotting the Siberian permafrost.