The jury is no longer out on how climate change has been influenced by man, since the dawn of the Industrial Revolution and especially in the last 70 years. But the jury has not even convened yet on many phenomena in the natural world, including some geological oddities. Thanks to National Geographic‘s news service for this story from the far reaches of Siberia:
Scientists narrow down the cause and think it is related to warming.
When a massive and mysterious hole was discovered in Siberia last July (see pictures), social media users pointed to everything from a meteorite to a stray missile to aliens to the Bermuda Triangle as possible causes. But the most plausible explanation seemed to be the explosive release of melting methane hydrate—an ice-like material frozen in the Arctic ground—thanks to global warming.
Now, scientists are arguing that the methane theory is unlikely, based on new satellite surveys released by Russian researchers that found dozens of new craters in Siberia.
“The jury is still out” on the cause of Siberia’s craters, says Carolyn Ruppel, chief of the U.S. Geological Survey’s Gas Hydrates Project. But she and other scientists say the new satellite mapping suggests another explanation that has to do with the rapid melting of ice cores called pingos.
A pingo is a plug of ice that forms near the surface over time and has a small mound or hill on top.
When an ice plug melts rapidly—as many have been, thanks to unseasonably warm temperatures in Siberia over the past year—it can cause part of the ground to collapse, forming a crater. But that process alone isn’t enough to explain the ejected rocks that have been found around the rim of the craters, which suggest some sort of explosion.
Instead, Ruppel theorizes that the craters were formed by a sudden release of natural gas that had been stored in the permafrost but was kept under pressure by the weight of the pingo.
This theory is bolstered by the Russian satellite data, which show pingos—they appear as small mounds—in the exact positions where the craters later formed.
There are many more pingos across Siberia, as well as on Alaska’s North Slope, so there’s substantial risk of additional craters opening up as the planet continues to warm, Ruppel says.
Read the whole article here.