South Asian black carbon is threatening the water sustainability of the Asian Water Tower

Long-range transport of black carbon from South Asia to the Tibetan plateau and its deposition on glaciers directly enhances glacier melt. This study finds that South Asian black carbon also indirectly affects the plateau's glaciers shrinkage by reducing the water supply over the southern Tibetan plateau. Black carbon enhances vertical convection and cloud condensation, resulting in water vapor depletion over the Indian subcontinent, the main moisture flux source for the southern Tibetan plateau. Increasing black carbon concentrations cause a decrease in summer precipitation over the southern Tibetan plateau, resulting in an average 11.0% glacier deficit mass balance from 2007 to 2016; this loss rises to 22.1% in the Himalayas. The direct (accelerated melt) and indirect (mass supply decrease) effects of black carbon are driving the glacial mass decline of the so-called "Asian Water Tower".

Junhua Yang, Shichang Kang, Deliang Chen, Lin Zhao, Zhenming Ji, Keqin Duan, Haijun Deng, Lekhendra Tripathee, Wentao Du, Mukesh Rai, Fangping Yan, Yuan Li, Robert R. Gillies