Timing of the Recent Migration and Intensification of the Southern Hemisphere Westerly Winds

Abstract

In recent decades, the Southern Hemisphere westerly winds have strengthened and migrated south, attributed to greenhouse gas emissions and stratospheric ozone depletion. However, the onset and acceleration of these drivers is coincident with the start of the instrumental record, thus, hindering our ability to determine the significance of the recent trends. Here, we present a novel wind reconstruction based on marine diatoms preserved in an Antarctic Peninsula ice core, providing a unique record to reconstruct westerly winds across the Pacific sector of the Southern Ocean (SO). The annually resolved record provides clear evidence that a southward migration of the Pacific sector westerly wind belt occurred in the 1960s, coupled with a prolonged strengthening trend. The poleward shift and acceleration of the westerly winds across this SO sector is unprecedented in the context of the past 140 years and coincident with the anthropogenically induced increase in greenhouse gases and ozone depletion.