The Interpretation of Karakoram Anomaly by High Karakoram Ice Core Record

Abstract

Glacier mass in the Karakoram region has increased since the mid-1990s in contrast to Himalayan glaciers. The scarcity and brevity of observations, including in situ observations and weather station data, limit our understanding of the Karakoram anomaly. Here, we present the stable water isotopes and snow accumulation records of Karakoram's first shallow ice core, covering 1998 to 2018. The decreased δ¹⁸O suggests an overall cooling trend in the Karakoram region for the early 21st century. In contrast, snow accumulation shows a significant increasing trend, which reveals that the Karakoram glacier has been getting more and more precipitation supplies recently. Using correlation field analysis and a backward trajectory model, we find that the decreased temperature and increased precipitation in the Karakoram are related to weakening westerlies. The northward shift of westerlies will transport colder water vapor from the North Atlantic to Karakoram, decreasing temperature and increasing precipitation in Karakoram. Our results indicated a trend of temperature cooling and precipitation increase trend in the Karakoram related to the weakened westerlies and the North Atlantic, which might explain the Karakoram anomaly that occurred in the Pamir-Karakoram-Kunlun region under the present climate change background. These results can provide new insights for predicting the changes in glacier mass in Karakoram and evaluating the variations in Asian water towers.