Circumpolar distribution and carbon storage of thermokarst landscapes

TLDR

Thermokarst, driven by thawing ice‑rich permafrost, causes land subsidence and distinctive landforms, and its acceleration from climate change threatens infrastructure while altering hydrology, ecology, and biogeochemistry. The study aims to provide a circumpolar assessment of thermokarst landscape distribution, defined by current landforms and areas prone to future development. The authors mapped thermokarst landscapes across the northern permafrost region, identifying existing thermokarst landforms and areas susceptible to future thaw. Thermokarst landscapes cover about 3.6 million km²—roughly 20 % of the northern permafrost region—with wetland, lake, and hillslope types contributing equally, and they store about half of the region’s below‑ground organic carbon, highlighting their importance for climate‑change greenhouse‑gas emissions.

Abstract

Abstract Thermokarst is the process whereby the thawing of ice-rich permafrost ground causes land subsidence, resulting in development of distinctive landforms. Accelerated thermokarst due to climate change will damage infrastructure, but also impact hydrology, ecology and biogeochemistry. Here, we present a circumpolar assessment of the distribution of thermokarst landscapes, defined as landscapes comprised of current thermokarst landforms and areas susceptible to future thermokarst development. At 3.6 × 10 6 km 2 , thermokarst landscapes are estimated to cover ∼20% of the northern permafrost region, with approximately equal contributions from three landscape types where characteristic wetland, lake and hillslope thermokarst landforms occur. We estimate that approximately half of the below-ground organic carbon within the study region is stored in thermokarst landscapes. Our results highlight the importance of explicitly considering thermokarst when assessing impacts of climate change, including future landscape greenhouse gas emissions, and provide a means for assessing such impacts at the circumpolar scale.