Future Changes in Northern Hemisphere Summer Weather Persistence Linked to Projected Arctic Warming

Abstract

AbstractUnderstanding the response of the large‐scale atmospheric circulation to climatic change remains a key challenge. Specifically, changes in the equator‐to‐pole temperature difference have been suggested to affect the midlatitudes, potentially leading to more persistent extreme weather, but a scientific consensus has not been established so far. Here we quantify summer weather persistence by applying a tracking algorithm to lower tropospheric vorticity and temperature fields to analyze changes in their propagation speeds. We find significant links between slower propagating weather systems and a weaker equator‐to‐pole temperature difference in observations and models. By end of the century, the propagation of temperature anomalies over midlatitude land is projected to decrease by −3%, regionally strongest in southern North America (−45%) under a high emission scenario (CMIP5 RCP8.5). Even higher decreases are found (−10%, −58%) in models which project a decreasing equator‐to‐pole temperature difference. Our findings provide evidence that hot summer weather might become longer‐lasting, bearing the risk of more persistent heat extremes.