Satellite data reveal southwestern Tibetan plateau cooling since 2001 due to snow-albedo feedback

Given the threats that climate change poses to solid water reservoirs on the Tibetan plateau (TP), there is significant interest in understanding spatial patterns of climate change and their causes. Weather station observations have been extensively examined, but are scarce, resulting in an incomplete understanding of climate change across the TP, particularly in the west. Using recent (2001-2015) satellite-based data sets (2 m air temperature, land surface temperature, albedo and snow cover), this study reveals that mean annual 2 m air temperature in the southwestern TP has decreased by 0.15 degrees C/decade in contrast to overall warming (+0.18 degrees C/decade) on the rest of the TP. Up to 45% (74%) of the variance in the annual (spring) 2 m air temperature can be explained by simultaneous change in snow-induced albedo in the southwestern TP. The free atmosphere column over this region and Northwest India is cooling, providing a favourable environment for the decrease in 2 m air temperature observed. Moreover, the anomalous water vapour transport into the southwestern TP is advantageous for increased snowfall and the associated decrease in 2 m air temperature. The implications of this anomalous cooling under global warming have yet to be fully considered, in particular for the futures of glaciers and snowpack over the Himalayan Mountains in the southwestern TP.