Role of the Bering Strait on the hysteresis of the ocean conveyor belt circulation and glacial climate stability

Abstract

Abrupt climate transitions, known as Dansgaard-Oeschger and Heinrich events, occurred frequently during the last glacial period, specifically from 80–11 thousand years before present, but were nearly absent during interglacial periods and the early stages of glacial periods, when major ice-sheets were still forming. Here we show, with a fully coupled state-of-the-art climate model, that closing the Bering Strait and preventing its throughflow between the Pacific and Arctic Oceans during the glacial period can lead to the emergence of stronger hysteresis behavior of the ocean conveyor belt circulation to create conditions that are conducive to triggering abrupt climate transitions. Hence, it is argued that even for greenhouse warming, abrupt climate transitions similar to those in the last glacial time are unlikely to occur as the Bering Strait remains open.

Post-glacial flooding of the Bering Land Bridge dated to 11 cal ka BP based on new geophysical and sediment records

“…However, the paleogeography of the Bering Land Bridge provides key boundary conditions for both human and animal migration pathways that must be considered in parallel with the archaeological history of the first human settlements in America. In addition, the reconnection between the Pacific and the Arctic oceans through the Bering Strait has been suggested to influence the Holocene climate evolution that followed the last glaciation (De Boer and Nof, 2004b;Hu et al, 2012;Ortiz et al, 2012;Shaffer and Bendtsen, 1994). The Bering Strait throughflow also provides one-third of the present-day freshwater input to the Arctic, and its associated heat transport controls the extent of the Arctic sea ice (Woodgate et al, 2012).…”

“…dampen abrupt climate transitions, thereby emphasizing the critical role of a Pacific-Arctic connection in Earth's climate system (De Boer and Nof, 2004b;Hu et al, 2012Hu et al, , 2015Sandal and Nof, 2008).…”

Revisiting meridional overturing bistability using a minimal set of state variables: stochastic theory

“…As such, it can re-align the associations between F ocn and F atm and S, effectively changing these fluxes as functions of S. In our specific numerical model, the Bering Strait is closed. Hu et al (2012) indicates the importance of this gateway to AMOC bistability. This illustrates the possibility for the need of an associated correction term in (Holocene) models where this gateway is closed.…”

“…McManus et al (2004) find AMOC cessation during the coldest deglacial interval and a cool North Atlantic when the AMOC was weak. Recently Hu et al (2012) found an absence of the AMOC-Off state in coupled climate model experiments when the Bering Strait is open; contrasting the bistability obtained when the Bering Strait is closed. They conclude that AMOC bistability must be a glacial feature, and explain the near-absence of abrupt climate transitions in the Holocene by a lack of AMOC hysteresis behaviour during interglacial times.…”

“…The AMOC, depicted in Fig. 1, is thought to be involved in this type of variability (Zahn et al 1997;Hu et al 2012). McManus et al (2004) find AMOC cessation during the coldest deglacial interval and a cool North Atlantic when the AMOC was weak.…”