Massive remobilization of permafrost carbon during post-glacial warming.

T Tesi,A Andersson,I Semiletov,O Dudarev,P Hill,R Noormets,M Jakobsson,F Muschitiello,Ö Gustafsson,R H Smittenberg,J E Vonk,N Kirchner

doi:10.1038/ncomms13653

Abstract

Recent hypotheses, based on atmospheric records and models, suggest that permafrost carbon (PF-C) accumulated during the last glaciation may have been an important source for the atmospheric CO2 rise during post-glacial warming. However, direct physical indications for such PF-C release have so far been absent. Here we use the Laptev Sea (Arctic Ocean) as an archive to investigate PF-C destabilization during the last glacial–interglacial period. Our results show evidence for massive supply of PF-C from Siberian soils as a result of severe active layer deepening in response to the warming. Thawing of PF-C must also have brought about an enhanced organic matter respiration and, thus, these findings suggest that PF-C may indeed have been an important source of CO2 across the extensive permafrost domain. The results challenge current paradigms on the post-glacial CO2 rise and, at the same time, serve as a harbinger for possible consequences of the present-day warming of PF-C soils.

Highlights

Recent hypotheses, based on atmospheric records and models, suggest that permafrost carbon (PF-C) accumulated during the last glaciation may have been an important source for the atmospheric CO2 rise during post-glacial warming
Despite the large amount of carbon held in the northern soils at the Last Glacial Maximum (LGM), we still do not have direct physical evidence to understand whether this large carbon reservoir remained dormant throughout the climate transition or whether the thermal reactivation of PF-C resulted in large-scale carbon redistribution between earth system compartments
Because of its extensive catchment (2.5 Â 107 km[2], the second largest in the Arctic and sub-Arctic regions), the soil carbon supplied by the Lena River to the Arctic Ocean integrates the signal from a vast permafrost domain, which, during the LGM, was largely dominated by the tundra-steppe biome but with the presence of woody taxa as well[22,23,24]

Summary

Introduction

Recent hypotheses, based on atmospheric records and models, suggest that permafrost carbon (PF-C) accumulated during the last glaciation may have been an important source for the atmospheric CO2 rise during post-glacial warming. Recent studies have suggested that the permafrost carbon (PF-C) stock in permanently frozen soils during the Last Glacial Maximum (LGM) might even have been substantially higher (by 700–1,000 Pg C) than the contemporary stock in high-latitude soils (1,300 Pg C)[2,3,4] Most of this megapool of PF-C was formed during the Pleistocene through episodes of sediment deposition, which, combined with the low temperatures, resulted in large burial of terrigenous biomass in soils that were not covered by ice sheets[3,4]. Our results suggest that thermal reactivation of dormant permafrost might have been an important source of carbon[2,12]

Methods

Results

Conclusion