Extremes of summer climate trigger thousands of thermokarst landslides in a High Arctic environment

Antoni G Lewkowicz,Robert G Way

doi:10.1038/s41467-019-09314-7

Antoni G Lewkowicz, Robert G Way

Open Access

https://doi.org/10.1038/s41467-019-09314-7

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Journal: Nature Communications	Publication Date: Apr 2, 2019
Citations: 244	License type: open-access

Affiliation: University of Ottawa, Queen's University

Abstract

Retrogressive thaw slumps (RTS) – landslides caused by the melt of ground ice in permafrost – have become more common in the Arctic, but the timing of this recent increase and its links to climate have not been fully established. Here we annually resolve RTS formation and longevity for Banks Island, Canada (70,000 km2) using the Google Earth Engine Timelapse dataset. We describe a 60-fold increase in numbers between 1984 and 2015 as more than 4000 RTS were initiated, primarily following four particularly warm summers. Colour change due to increased turbidity occurred in 288 lakes affected by RTS outflows and sediment accumulated in many valley floors. Modelled RTS initiation rates increased by an order of magnitude between 1906–1985 and 2006–2015, and are projected under RCP4.5 to rise to >10,000 decade−1 after 2075. These results provide additional evidence that ice-rich continuous permafrost terrain can be highly vulnerable to changing summer climate.

Highlights

– have become more common in the Arctic, but the timing of this recent increase and its links to climate have not been fully established
Retrogressive thaw slumps (RTS) were observed in entirely new locations across Banks Island during the high initiation years of 2011–2013 which suggests that vulnerable areas may exist at the landscape scale outside the current concentrations
The vast majority of these new thermokarst features were first observed in the Timelapse dataset in the years immediately following the four warm summers of 1998, 2010, 2011 and 2012

Summary

Introduction

– have become more common in the Arctic, but the timing of this recent increase and its links to climate have not been fully established. These rates reflect relatively low mean summer air temperatures for Banks Island and the absence of extremely warm July–August temperatures for most of the century (Fig. 8a). The modelled total number of active RTS, calculated from initiation and longevity rates, is greater than that observed at the start of the Timelapse period (Fig. 8c).

Results

Conclusion