Changing Northern Hemisphere Weather Linked to Warming Amplification in High Mountain Asia

Abstract High Mountain Asia (HMA) is a global warming hotspot, but its impact on extreme weather-related synoptic temperature variability (STV) over the Northern Hemisphere remains unknown. Using observations and modeling, we find amplified HMA warming increased summer STV in Canada and Russia but decreased winter STV in Eastern Europe and the Nordic Seas (>19%, 1940-2022), primarily through high-frequency temperature advection. This results from HMA warming-driven changes in temperature gradients and high-frequency atmospheric circulation variability. Summer temperature gradients strengthened in Canada and Russia but weakened in the Nordic Seas and Eastern Europe in winter, while reduced synoptic circulation variability dominated Eastern Europe's STV decline. These patterns result from HMA warming's hemispheric-scale teleconnections, altering temperature distributions and atmospheric circulation stability through modified jet streams, Rossby waves, and associated feedbacks, including air-sea interactions. Beyond local effects on the Third Pole environment, our study demonstrates HMA warming's significant remote influence on Northern Hemisphere weather.