Methane-driven late Pleistocene δ¹³C minima and overflow reversals in the southwestern Greenland Sea

Abstract

A core transect across the southwestern Greenland Sea reveals coeval events of extremely negative planktic and benthic δ¹³C excursions between 40 and 87 ka. The most pronounced event, event 1, began at peak Dansgaard-Oeschger stadial 22 (85 ka) with a duration of 18 k.y. During this episode, incursions of Atlantic Intermediate Water caused a bottom-water warming of up to 8 °C. The amplitude, timing, and geographic pattern of the δ¹³C events suggest that this bottom-water warming triggered clathrate instability along the East Greenland slope and a methane-induced depletion of δ¹³C_DIC (DIC— dissolved inorganic carbon). Since δ¹³C event 1 matches a major peak in atmospheric CH₄ concentration, this clathrate destabilization may have contributed to the rise in atmospheric CH₄ and thus to climate warming over marine isotope stage 5.1.