Martens Jannik, Wild Birgit, Muschitiello Francesco, O'Regan Matt, Jakobsson Martin, Semiletov Igor, Dudarev Oleg V, Gustafsson Örjan
Department of Environmental Science, Stockholm University, 11418 Stockholm, Sweden.
Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, Sweden.
Sci Adv. 2020 Oct 16;6(42). doi: 10.1126/sciadv.abb6546. Print 2020 Oct.
Carbon cycle models suggest that past warming events in the Arctic may have caused large-scale permafrost thaw and carbon remobilization, thus affecting atmospheric CO levels. However, observational records are sparse, preventing spatially extensive and time-continuous reconstructions of permafrost carbon release during the late Pleistocene and early Holocene. Using carbon isotopes and biomarkers, we demonstrate that the three most recent warming events recorded in Greenland ice cores-(i) Dansgaard-Oeschger event 3 (28 ka B.P.), (ii) Bølling-Allerød (14.7 to 12.9 ka B.P.), and (iii) early Holocene (11.7 ka B.P.)-caused massive remobilization and carbon degradation from permafrost across northeast Siberia. This amplified permafrost carbon release by one order of magnitude, particularly during the last deglaciation when global sea-level rise caused rapid flooding of the land area thereafter constituting the vast East Siberian Arctic Shelf. Demonstration of past warming-induced release of permafrost carbon provides a benchmark for the sensitivity of these large carbon pools to changing climate.
碳循环模型表明，北极过去的变暖事件可能导致了大规模的永久冻土融化和碳的重新活化，从而影响了大气中的二氧化碳水平。然而，观测记录稀少，阻碍了对晚更新世和全新世早期永久冻土碳释放进行空间广泛且时间连续的重建。利用碳同位素和生物标志物，我们证明了格陵兰冰芯记录的最近三次变暖事件——（i）丹斯加德-奥舍格事件3（约28 ka B.P.）、（ii）博林-阿勒罗德暖期（14.7至12.9 ka B.P.）以及（iii）全新世早期（约11.7 ka B.P.）——导致了西伯利亚东北部永久冻土的大量重新活化和碳降解。这使得永久冻土碳释放量增加了一个数量级，特别是在末次冰消期，当时全球海平面上升导致陆地迅速被淹没，这片陆地随后构成了广阔的东西伯利亚北极大陆架。过去变暖导致永久冻土碳释放的证明为这些巨大碳库对气候变化的敏感性提供了一个基准。
