8.2 ka event North Sea hydrography determined by bivalve shell stable isotope geochemistry

Abstract

The abrupt 8.2 ka cold event has been widely described from Greenland and North Atlantic records. However, its expression in shelf seas is poorly documented, and the temporal resolution of most marine records is inadequate to precisely determine the chronology of major events. A robust hydrographical reconstruction can provide an insight on climatic reaction times to perturbations to the Atlantic Meridional Overturning Circulation. Here we present an annually-resolved temperature and water column stratification reconstruction based on stable isotope geochemistry of Arctica islandica shells from the Fladen Ground (northern North Sea) temporally coherent with Greenland ice core records. Our age model is based on a growth increment chronology obtained from four radiometrically-dated shells covering the 8290–8100 cal BP interval. Our results indicate that a sudden sea level rise (SSLR) event-driven column stratification occurred between ages 8320–8220 cal BP. Thirty years later, cold conditions inhibited water column stratification but an eventual incursion of sub-Arctic waters into the North Sea re-established density-driven stratification. The water temperatures reached their minimum of ~3.7 °C 55 years after the SSLR. Intermittently-mixed conditions were later established when the sub-Arctic waters receded.

Holocene climate and oceanography of the coastal Western United States and California Current System

“…The end of the early Holocene is marked by a large-scale Northern Hemisphere cooling event initiated by an abrupt drainage of Lake Agassiz into the North Atlantic that weakened Atlantic Meridional Overturning Circulation, and is 305 well documented in many records (Thomas et al, 2007;Matero et al, 2017;Estrella-Martínez et al, 2019;Voarintsoa et al, 2019). Although this is a globally well described event, relatively few records (fewer than 10 records reviewed in this paper) from the Northeastern Pacific and Western United States record impacts of this event.…”

Oceanic cooling recorded in shells spanning the Medieval Climate Anomaly in the subtropical eastern North Atlantic Ocean

“…While some research has found that more rapid variations in seawater d 18 O values have occurred due to catastrophic, largescale events such as the 8.2kyr event (e.g. Estrella-Martínez et al, 2019a), the MCA has not been shown to be one of these events. Accordingly, as there has been no significant global glaciation between the MCA and the present, it is assumed that the modern global seawater d 18 O values are analogous to those of the MCA.…”

Comment on cp-2021-109

“…well documented in many records (Thomas et al, 2007;Matero et al, 2017;Estrella-Martínez et al, 2019;Voarintsoa et al, 2019). Although this is a globally well described event, relatively few records (fewer than 10 records reviewed in this paper) from the Northeastern Pacific and Western United States record impacts of this event.…”