Stephan Harrison, Adina Racoviteanu, Sarah Shannon, Darren Jones, Karen Anderson, Neil Glasser, Anna Ranger, Arindan Mandal, Bramha Vishwakarma, Jeff Kargel, Dan Shugar, Umesh Haritashya, Li Dongfeng, Aristeidis Koutroulis, Klaus Wyser, Sam Inglis

In High Mountain Asia (HMA) climate change threatens mountain water resources as glaciers melt, and the resulting changes in runoff and water availability are hypothesised to have considerable negative impacts on ecological and human systems. Numerous assessments of the ways in which glaciers will respond to climate warming have been published over the past decade. Many have used climate model projections to argue that HMA glaciers will melt significantly this century. However, we show that this is only one way in which glaciers might respond. An alternative scenario is one in which increasing valley-side instability releases large amounts of rock debris onto glacier surfaces. This then inhibits glacier melting to the extent that glacier ice becomes preserved under a thick rock debris cover. We call this alternative scenario the Paraglacial Transition and this has rarely been articulated in the context of HMA. In this paper we discuss this landscape transition and use understanding of past glacier dynamics to assess its likelihood. Better understanding of how HMA glaciers respond to climate change is critical for underpinning climate change adaptation strategies and to ensure that this highly populated region is in a strong position to meet sustainable development goals.