The Batagay crater, dubbed the gateway to the underworld by locals, first appeared in the middle of the 20th century after changes to land use, which caused erosion to the ice-rich region. It has been expanding rapidly and substantially since the 1990s. According to Science magazine, the rate has increased since 2016, and it is now expanding by between 39 and 45 feet per year.
The megaslump formed as a result of a geological process known as thermokarst. This is where ice locked inside permafrost—ground that is permanently frozen—melts. As the ice turns to water and the earth thaws, ground strength is reduced and the volume decreases.
Over the coming years and decades, this process could lead to the emergence of other thermokarst craters like Batagay, experts have said. Recent research shows the Arctic has been warming about twice the rate of the rest of the world for the last 30 years. Climate change has also been implicated in the heatwave that has hit Siberia in recent months, during which temperature records have been smashed.
Marc Macias-Fauria, Associate Professor in Physical Geography at the University of Oxford, told Newsweek that the recent heatwave will have enhanced permafrost thaw in the region. Permafrost can stretch for over 3,200 feet down beneath the surface. Every summer the “active layer” at the top will thaw, leaving the lower layers frozen. With more heating, the bigger the active layer. But he said another, more worrying process, can also be started in the permafrost through excess heat.
“In many regions of the permafrost region, more so the more north you are, permafrost is very rich in ice. Ice binds sediments together, but once it is liquid water, these break loose and erosion can start,” he said in an email. “Large ice lenses and high ice concentration in general mean that the possibility of runaway processes—permafrost collapse—increases when the active layer is deeper…In these areas, one event can be catastrophic and create brand new landscapes, forming or draining lakes, eroding river courses, coastal edges, and emitting very large amounts of greenhouse gases.”
Julian Murton, Professor Of Permafrost Science at the University of Sussex, said the heatwave in Siberia will have caused the Batagay megaslump to grow because of the higher air temperatures. Increased meltwater can also erode the permafrost, exacerbating thaw in the terrain. “The so-called ‘crater’ at Batagay is really not a crater but a huge retrogressive thaw slump [or] ‘megaslump,’” he told Newsweek in an email. “It formed by a combination of thermal erosion—as meltwater streams incised the landscape—and thermokarst subsidence, as ground ice melted and the land surface subsided and retreated.”
The increased growth at Batagay, he said, could mean “other thermokarst landforms may develop and grow over the coming decades, particularly if the landscape is disturbed by factors such as vegetation clearance or forest fire.”
Macias-Fauria said once erosion at a permafrost site starts, any more liquid water can enhance that erosion. “I reckon Batagay will grow as far as topography/substrate will allow it to grow,” he said. “I have no idea how much. Mostly, the Batagay indicated the fragile and highly unstable and rapid nature of permafrost geomorphological processes in places rich in ground ice.”
