On the Yamal Peninsula, a remote region in northwestern Siberia, the appearance of huge craters has intrigued scientists and local residents for almost a decade. In 2014, the first crater, about 50 meters deep and 70 meters in diameter, was unexpectedly discovered in this area, surrounded by debris that suggested something had exploded from the bowels of the earth.
Since that first discovery, scientists and local residents have identified more craters on the Yamal and Gydan peninsulas, unleashing all kinds of theories about their possible causes. Thus, what began as an isolated enigma turned out to be the first record of a phenomenon exclusive to the Arctic: could they be meteorites? Or natural gas explosions? Now, a recent study, published in the journal Geophysical Research Letters, suggests that the answer is more complex and has to do with a delicate balance that climate change is upsetting.
“It’s detective work,” explains Ana Morgado, a chemical engineer at the University of Cambridge and co-author of the study in a press release. of the American Geophysical Union (AGU).
Criopeg, special layer of permafrost
Beneath Yamal’s seasonally frozen soil lies a thick layer of clay permafrost. But the key to these explosions lies in a special layer within the permafrost called cryopeg. These pockets of salt water are relics of ancient prehistoric seas, and remain liquid thanks to their high salinity and the pressure exerted on them by the frozen ground. But that’s not all. Just below the cryopegs are methane hydrates: crystallized solids of methane and water that remain stable under high pressure and low temperature conditions.
But the question remains: what makes all this explode? As geophysicist Julyan Cartwright, from the Spanish National Research Council, explains, there were two possibilities: “Either a chemical reaction occurs, like that of dynamite, or you inflate the tire of your bicycle until it explodes: that’s physics.”
The absence of lights or combustion products ruled out the first option. The answer lay in physics, specifically osmosis: the movement of water to equalize concentrations of dissolved substances.
Osmotic pump
Climate change is causing the topsoil to thaw to increasing depths. When this meltwater reaches the extraordinarily salty cryopegs, an osmotic pump effect is triggered. The water tries to balance the salt concentration, but without enough space, the pressure increases until cracks form in the permafrost.
And here comes the final blow: these cracks cause a sudden drop in pressure that destabilizes the underlying methane hydrates. The result is an explosion that ejects earth, rock and ice, creating these mysterious craters.
Implications for global warming
Although these events are relatively infrequent, the amounts of methane released are significant. Methane is a much more potent greenhouse gas than carbon dioxide in the short term, meaning these explosions could have a significant impact on global warming.
“It could be a rare phenomenon,” says Morgado. “But the amount of methane that is released could have a pretty big impact on global warming.”
Interestingly, this phenomenon has only been observed on the Yamal and Gydan peninsulas. The specific combination of permafrost, cryopegs and methane hydrates creates a unique geological scenario that, added to global warming, triggers these underground explosions.
“We are talking about very, very specific conditions,” says Morgado. “It’s a very niche geological space.”
Still, as science advances in its understanding of the role of climate change in these phenomena, it is becoming clear that events in the coldest areas of the world, although very unique, can have significant consequences for the global climate. . In this context, as long as temperatures continue to rise, the craters of Siberia will continue to be clear indicators of the rapid changes that our planet is experiencing.
Edited by Felipe Espinosa Wang with information from AGU, The Guardian and Live Science.
