North Atlantic and sub-Antarctic Ocean temperatures: possible onset of a transient stadial cooling stage

Abstract

The ice core glacial-interglacial record of the last 450 kyr (Cortese et al. Paleogeogr Paleoclimatol 22:4, 2007), development of cold ice meltwater regions at fringes of the Greenland and the West Antarctic ice sheets, and climate projections by Hansen et al. (Atmos Chem Phys 16:3761–3812, 2016), support a relation between ice sheet melting and the cooling of neighboring ocean zones by ice meltwater. Several factors lead to cooling of parts of the North Atlantic Ocean and adjacent lands, including the following: (A) a slowdown of the Atlantic meridional overturning circulation (AMOC); (B) flow of cold ice meltwater from the Greenland ice sheet into the North Atlantic Ocean; (C) undulation and weakening of the jet stream at the Arctic boundary due to a rise in temperature in the Arctic circle at twice the rate of warming at lower latitudes and the ice-water albedo flip. Penetration of Arctic-derived cold air masses southward through a weakened jet stream boundary ensues in extreme weather events in North America and Europe. The slowdown of the AMOC (Caesar et al. Nature 556:191–196, 2018; Praetorius Nat Clim Chang 5:475–480, 2018; Thornalley et al. Nature 556:227–230, 2018; Smeed et al. Geophys Res Lett 45(3):1527–1533, 2018) and growing cold ocean region (Rahmstorf et al. Nat Clim Chang 5:475–480, 2015) may herald the onset of a stadial event. A large-scale stadial event, possibly on the scale of the 8.3–8.2 kyr-old Laurentian melt event, or even the 12.9–11.7-kyr-old Younger Dryas stadial (Carlson Encycl Quat Sci 3:126–134, 2013), could ensue from advanced melting of both the Greenland ice sheet and the Antarctic ice sheet. A stadial would be succeeded by the resumption of warming driven by a continuing rise in greenhouse gas concentrations and amplifying feedback effects. These projections need to be examined vis-a-vis the continuous linear IPCC temperature rise models.