Increasing Pleistocene permafrost persistence and carbon cycle conundrums inferred from Canadian speleothems.

Autor:	Biller-Celander N; Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA 02467, USA., Shakun JD; Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA 02467, USA. jeremy.shakun@bc.edu., McGee D; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA., Wong CI; Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA 02467, USA., Reyes AV; Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada., Hardt B; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA., Tal I; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA., Ford DC; Department of Geography and Earth Sciences, McMaster University, Hamilton, Ontario L8S 4K1, Canada., Lauriol B; Department of Geography, Environment and Geomatics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
Jazyk:	angličtina
Zdroj:	Science advances [Sci Adv] 2021 Apr 28; Vol. 7 (18). Date of Electronic Publication: 2021 Apr 28 (Print Publication: 2021).
DOI:	10.1126/sciadv.abe5799
Abstrakt:	Permafrost carbon represents a potentially powerful amplifier of climate change, but little is known about permafrost sensitivity and associated carbon cycling during past warm intervals. We reconstruct permafrost history in western Canada during Pleistocene interglacials from 130 uranium-thorium ages on 72 speleothems, cave deposits that only accumulate with deep ground thaw. We infer that permafrost thaw extended to the high Arctic during one or more periods between ~1.5 million and 0.5 million years ago but has been limited to the sub-Arctic since 400,000 years ago. Our Canadian speleothem growth history closely parallels an analogous reconstruction from Siberia, suggesting that this shift toward more stable permafrost across the Pleistocene may have been Arctic-wide. In contrast, interglacial greenhouse gas concentrations were relatively stable throughout the Pleistocene, suggesting that either permafrost thaw did not trigger substantial carbon release to the atmosphere or it was offset by carbon uptake elsewhere on glacial-interglacial time scales. (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)
Databáze:	MEDLINE
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