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It's 2020, so "mysterious giant crater opens up in Siberia" barely elicits more than a quick nod and a "yes, I expect so," which is why you may have missed it earlier this year when precisely that was discovered.
A film crew first found the hole when they were flying over the Yamal Peninsula – an area known as "the end of the world" by locals – by helicopter. Whatever the explosion that caused it was, it left chunks of rock, ice and soil scattered hundreds of meters across the landscape.
The crater isn't the first of its kind in Siberia. In fact, it brings the total of these holes to 17. As you'd expect, it's not a great sign when an explosion, some of which have been heard from 100 kilometers (62 miles) away, leaves a gigantic maw in the ground. When it happens in a place called "the end of the world" you might even think it a little on the nose, even for 2020.
Though nobody has been harmed by them, as they occur far from where anybody lives, it could be a sign of melting permafrost following rising temperatures in the region.
When they first began to appear in 2014, it was unclear what was causing them, though everything from meteors to aliens was suggested by both scientists and cranks. We now know they are likely caused by a buildup of gas underneath the surface.
Satellite analysis conducted earlier this year showed that the craters all occurred in places where previously there had been mounds (or pingos, small hills with an ice core). The mounds themselves, around 2-6 meters (6.5-20 feet) high, had grown rapidly before the explosions, much more quickly than the surrounding pingos, which tend to rise and fall with the seasons, and collapse in on themselves rather than explode.
Another study that took samples from the bottom of the craters concluded that the craters are likely caused by intensive gas emissions, specifically after a buildup of methane under the surface. "The accumulated methane created pressure in areas with tabular ground ice at the clay–sand interface, which resulted in the development of a mound‐predecessor," the study authors wrote. "As pressure within this mound‐predecessor exceeded the confining strength of the overlying substrate, a gas emitting crater erupted."
As the permafrost thaws from rising temperatures, bacteria and other microbes also thaw out and immediately get back to work pumping out methane. When the gas gets trapped by the ground above, it creates these high-pressure mounds, which eventually blow their top.
As the temperatures increase in the area, we may see more of this phenomenon occurring, which is bad news given that methane is a greenhouse gas, and leads to yet more warming.
“The craters are a very shocking indicator of what is happening in the Arctic more widely,” Sue Natali of the Woodwell Climate Research Center in Woods Hole, Massachusetts told BBC Future.
“When you look at changes that are happening across this landscape, some are occurring gradually and others abruptly. Very few are occurring explosively, but it brings attention to how all these changes contribute to the greenhouse gases in the atmosphere.”
