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Scientists are putting forward a new explanation for the giant exploding craters that seem to be randomly appearing in the Siberian permafrost.
These craters, first spotted in 2012, have been popping up in the deserted Siberian permafrost, puzzling scientists.
They can be substantial, reaching more than 160 feet in depth and 65 feet in width, and blasting chunks of debris hundreds of feet away.
Some reports have suggested the blasts can be heard 60 miles away.
Now scientists are proposing that hot natural gas seeping from underground reserves might be behind the explosive burst.
The findings could explain why the craters are only appearing in specific areas in Siberia.
The area is known for its vast underground reserves of natural gas, the study's lead author Helge Hellevang, who is a professor of environmental geosciences at the University of Oslo in Norway, told Business Insider.
"When climate change or atmosphere warming is weakening the other part of the permafrost, then you get these outbursts — only in Siberia," he said.
Gas makes the hole, but it comes from deep reserves
Permafrost traps a lot of organic material. As temperatures rise, it thaws, allowing that mulch to decompose. That process releases methane.
So scientists had naturally proposed the methane seeping from the permafrost itself was behind the craters.
This isn't a crazy thought. It's notably the process that's thought to lead to thermokarsts, lakes that appear in areas where permafrost is melting, which bubble with methane and can be lit on fire.
But that doesn't explain why the so-called exploding craters are so localized.
Only eight of these craters have been identified so far, all within a very specific area: the Western Siberian Yamal and Gydan peninsulas in Northern Russia.
Exploding lakes, by contrast, are seen in a wide variety of areas where permafrost is found, including Canada.
Hellevang and his colleagues suggest there's another mechanism at play: hot natural gas, seeping up through some kind of geological fault, is building up under the frozen layer of soil and heating the permafrost from below.
Those hot gas plumes would help thaw the permafrost from the bottom, making it weaker and more likely to collapse.
"This explosion can only happen if the permafrost is thin and weak enough to break," said Hellenvang.
Rising temperatures melt the upper layer of the permafrost at the same time. This creates the perfect conditions for the gas to be freed suddenly, triggering either an explosion or a "mechanical collapse" caused by the gas, which is under pressure.
That creates the crater, Hellevang and colleagues are suggesting.
The area is rife with natural gas reserves, which lines up with Hellevang and colleagues' theory, per the study.
"This area is one of the largest petroleum provinces in the world," he said.
According to the scientist's model, more of these craters could have been created and have since disappeared as nearby water and soil fell in to fill the gap.
"This is a very remote area, so we don't really know the true number," he said.
"If you look at the satellite image of the Yamal Peninsula, there are thousands of these round plate-like depressions. Most or all of them could have been thermokarsts, but potentially they could also be earlier craters that have formed," he said.
The hypothesis was published on the online server EarthArXiv last month. The article has not yet been validated by a review from scientific peers.
A dangerous hypothesis for the climate crisis
While the idea has merit, more evidence will be needed to show these reserves of gas are building under the permafrost, Lauren Schurmeier, an Earth scientist at the University of Hawai'i who researches the topic, told New Scientist.
Still, if the hypothesis is found to be correct, this could spell trouble for climate models.
Natural gas is full of methane, a potent greenhouse gas. This could mean the craters are acting like huge chimneys through which the damaging chemical could be freed suddenly into the atmosphere, Thomas Birchall at the University Centre in Svalbard, Norway, told New Scientist.
"If that's the standard way that large accumulations fail then you're dumping a lot of methane in a very short time," he told New Scientist.
Hellenvang, however, exercised caution. If this phenomenon only exists in this very limited area, it may be that the impact is minute on a global scale. While there is likely a large amount of methane stored in underground reserves, it's not clear how much of that could get out.
"I think what we need to do is understand first and foremost how much methane is naturally leaking from these kind of systems, and then compare that to how much methane that is actually within the permafrost for organic matter," Hellenvang said.
"Then we can have a more realistic budget on how much can be released because of atmospheric heating or climate change," he said.
This article was originally published by Business Insider.
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