84-6 Rapid collapse of a Siberian landscape revealed by satellite imagery: widespread permafrost thaw slump failure occurs in days; downstream sediment transport is elevated for years

Abstract:

Warmer temperatures and changing precipitation patterns in the Arctic appear to be increasing erosion, but the spatial distribution and timing of increased erosion is not yet clear. In 2020, the Taymyr Peninsula, Siberia, Russia, experienced a historic heat wave that coincided with rapid expansion and generation of more than 1,700 large permafrost thaw slumps. We investigate this regional mass wasting event to better understand thaw slump timing and downstream geomorphic effects. We used repeat satellite imagery to identify slump failure with two approaches: 1) a machine learning algorithm identified slump occurrence from planform area changes, and 2) a record of suspended sediment concentration (SSC), generated from near-daily Sentinel-2 imagery, identified slump occurrence by changes in river sediment transport. Both approaches indicate widespread hillslope failure in August 2020, when temperatures were at a sustained maximum and a moderate precipitation event occurred (14 mm). Change-point analysis of the SSC record indicates a regionally consistent step change in SSC, with that change occurring at nearly all river sites on August 4 (10 sites), and August 5 (6 sites). Control rivers have either non-significant change points or change points distributed through the 2020 season. The temporal coherence of this widespread failure suggests that the region’s hillslopes failed en masse in just 1 to 3 days, creating the densest complex of thaw slumps on earth. SSC in the region continued to increase from 2021–2024, scaling with the percent of upstream area covered by slumps. The post-2020 period has the four highest average SSC years in the 40-year Landsat record (1985–2025). Channels downstream have continually adjusted for five years by widening, frequently switching channels, and aggrading.

These lines of evidence indicate that regional failure of a permafrost landscape can occur in just a matter of days, with long-lived geomorphic effects. It remains to be seen whether a combination of susceptible underlying geology and anomalous warm temperatures makes this a globally unique event. However, we find that the probability of such temperatures occurring has increased more than 1000-fold in Siberia since the mid-20th century, likely also the case elsewhere in rapidly warming high latitudes.​​​​​​​​​

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