Heterogenous westerly shifts linked to Atlantic meridional overturning circulation slowdowns

Abstract

The mid-latitude westerly winds are a major component of the global atmospheric circulation and a dominant factor in mid-latitude climate change. Understanding their behaviour and the controls on their variations under different climate background states is essential for assessing climate system feedback. Here we present a midlatitude North Pacific Ocean aeolian dust record from core NP02 through the last glacial cycle, during which extreme and abrupt climatic oscillations occurred. We find low dust contents during Heinrich stadials 2, 4, 5, and 5a that we attribute using proxy-model comparison to westerly transportation path changes associated with Atlantic meridional overturning circulation (AMOC) reductions, which caused North Atlantic cooling and modified the westerly wave train pattern, particularly over the Tibetan Plateau. The finding that AMOC variations had significant impacts on the westerlies half-way around the world, through ocean-atmosphere interactions, improves understanding of large-scale westerly sensitivity to different climate states.