Influence of the North Atlantic subpolar gyre circulation on the 4.2 ka BP event

Abstract. The 4.2 ka BP event, spanning from ca 4200 to 3900 cal yr BP, has been documented in numerous archaeological data and continental archives across the northern hemisphere as an abrupt shift to dry and cold climate. However, data on synchronous ocean circulation changes are notably lacking thus preventing from getting a full insight into the physical mechanisms responsible for this climate deterioration. Here, we present two high-resolution sea surface temperature records from key locations in the subpolar gyre and off North Iceland in the vicinity of the polar front obtained from alkenone paleothermometry. Our data evidence a temperature dipole pattern in the subpolar North Atlantic between 4400−4100 yr BP, which combined with other paleoclimatic records from the North Atlantic/Euro-Mediterranean suggests a significant reduction of the subpolar gyre circulation possibly associated with atmospheric blocked regimes.