The role of the formation and destruction of the Hudson Strait glacial ice dam in changes of climate and sea level during the Last Interglacial-Glacial transition

Robert G Johnson

doi:10.24297/jns.v8i.9055

Abstract

During the Last interglacial period of constant sea level, large coral reefs formed on the tectonically rising island of Barbados, and a broad lagoon with a small barrier reef formed at the Cane Vale site. The constant sea level was ended by a rapid glaciation, causing a fall of world sea level of 2.4 m, as measured by surveys of features associated with breaking waves on Barbados. The fall began about 120 ka BP, and lasted roughly 400 years, according to a lake pollen record from western Europe. That rapid fall was terminated at a wave-cut step on Barbados and with a quite small reversal in falling sea level. The rise was caused by rapid melting of the marine-based Barents Sea ice dome and other ice masses, due to a restored strong Atlantic Meridional Overturning Circulation (AMOC) flow. The sea level fall then resumed until it was halted at a wave-cut step at a world sea level 12.3 m below the last interglacial level, as recorded at the University of the West Indies site on Barbados. Following the erosion of that second step, a zonal northern North Atlantic circulation prevailed, causing a glacial ice-volume decrease and rise in sea level of 3.8 m. These two sea level fall reversals were caused respectively by the formation and destruction of a Hudson Strait ice dam and the resulting increase and much later decrease in the rate of AMOC flow.

Highlights

2.1 BackgroundEarlier workers have described the series of coral reef terraces that record past interglacial sea stands on the tectonically uplifted Island of Barbados[1,2,3,4]
The widespread ongoing interest in the cause of the Heinrich event, H0, that started the Younger Dryas interval of arctic climate in northwestern Europe was brought to a sharp focus by the report in 2008 that the cold event in Europe began in only one year[6]
A few hundred years after the transition began, formation of the Hudson Strait ice dam ended a large flood of fresh water through Hudson Strait into the high-latitude North Atlantic, a flood that had been caused by the extremely high rate of precipitation west of Greenland

Summary

Method

The paleo sea level changes found in the fossil record of tectonically uplifted Barbados and reported here were measured in surveys made during six expeditions to Barbados from 1991 to 1998. The changes in the elevation of world sea level were stratigraphically referenced to the constant world sea level at the time of the last interglacial, 125 ka BP to 120 ka BP. These sea level changes during the following interglacial-glacial climate transition are of interest because they reflect the effects of oceanic circulation changes that resulted from oceanic interactions with glacial events in the high latitude northern North Atlantic, not all of which were recognized at the time of the surveys. A correlation between oceanic circulation variations and sea level changes during the Last Interglacial-Glacial transition is proposed with supporting evidence from the island of Barbados

Background

Findings

Summary