Climate security

Siberia’s ‘gateway to the underworld’ grows as record heat wave thaws permafrost

On a spring day in 2019, Alexander Kizyakov rappelled down the 60-meter headwall of the Batagay megaslump in eastern Siberia, pausing to chisel out chunks of ice-rich soil that had been frozen for eons. “One of my hobbies is rock climbing,” says Kizyakov, a permafrost scientist at Lomonosov Moscow State University. Colleagues below sampled the most ancient soil along the base of the cliff. Such work is too dangerous in summertime, when the constant crackling of melting ice is punctuated by groans as slabs of permafrost, some as big as cars, shear off the headwall.

Known to locals as the “gateway to the underworld,” Batagay is the largest thaw slump on the planet. Once just a gully on a slope logged in the 1960s, the scar has expanded year by year, as the permafrost thaws and meltwater carries off the sediment. Now more than 900 meters wide, it epitomizes the vulnerability of permafrost in the Arctic, where temperatures have shot up twice as fast as the global average over the past 30 years.

But it is also a time capsule that is seducing scientists with its snapshots of ancient climates and ecosystems. “It’s a mind-blowing place,” says Thomas Opel, a paleoclimatologist at the Alfred Wegener Institute. Dates from ice and soil gathered at Batagay show it holds the oldest exposed permafrost in Eurasia, spanning the past 650,000 years, Opel and colleagues reported in May at the European Geosciences Union’s online general assembly. That record could reveal how permafrost and surface vegetation responded to past warm climates. “It gives us a window into times when permafrost was stable, and times when it was eroding,” Opel says.