Tracing the Northern Hemisphere Westerlies - Published in Nature January 2021

“Poleward and Weakened Westerlies during Pliocene Warmth” published in Nature

The prevailing mid-latitude westerly winds, known as the “westerlies”, are integral to regional and global climate. Over the last several decades, the location and strength of the westerlies has been changing, likely because of anthropogenic climate change. In order to better understand this phenomena, we used ocean sediments from the North Pacific Ocean to reconstruct the position and intensification of the westerly winds during the Pliocene, approximately 3-5 million years ago when temperatures were a few degrees higher than today and CO2 was around 400 ppm, similar to today. Our work, published in the January issue of Nature, indicates that during the warm parts of the Pliocene, the westerlies, globally, were located closer towards the poles, and were weaker, than during the colder intervals afterwards. By using the Pliocene as an analogue for modern global warming, it seems likely that the movement of the westerlies towards the poles observed in the modern era will continue with further human-induced warming.