Temperature modulation of Northern Mid-Latitude Westerly winds intensity and displacement across the warm Pliocene

Abstract

The mid-latitude westerly winds are fundamental components of the Earth's climate system. However, their detailed variations during the entire Pliocene, a critical epoch often considered the closest analogue to future climate scenarios, remain poorly constrained. Here, we investigate the continuous, long-term evolution of Northern Hemisphere Mid-latitude Westerly winds (NHMW) between 6.5 and 2.5 Ma, using diatoms, aeolian dust grain size, and chemical weathering conditions from a sediment core in the central-north Pacific Ocean. Our records suggest that NHMW weakened and shifted northward from ∼5.8 to 4.4 Ma, followed by a sustained strengthening and equatorward shift after ∼4.4 Ma. NHMW dynamics during the Pliocene were linked tightly to the sea surface temperature gradient between tropical and temperate regions and affected the strength of the Asian Summer Monsoon (ASM), with weaker and more poleward NHMW increasing the intensity of and rainfall generated by the ASM. These findings underscore the importance of past dynamics of NHMW for predicting the hydroclimatological impacts of future global climate change on the functioning of major regional ocean-atmosphere and rainfall systems as the earth continues to warm.