Atmospheric dynamic constraints on freshwater sourced from the Tibetan Plateau under Paris climate pledges

Abstract

Almost one-fifth of the world’s population relies on rivers originating from the Himalayas and Tibetan Plateau. How global warming will impact runoff change in this water tower of Asia has attracted worldwide attention. Yet, their picture under Paris climate pledges is still a montage due to “very low” confidence in future precipitation changes. we introduce an atmospheric dynamic framework to constrain future precipitation changes from climate models by the end of this century. We then constrain runoff changes from scaling laws from precipitation and evapotranspiration and glacier melt contributions. The outcome is a smaller increase of precipitation by about a factor of two, and the net increase of June-to-September runoff is estimated to increase by 3.1% to 6.8% for global warming levels comprised between 1.5 and 4°C. Although ubiquitous increase in upstream runoff is found across basins, the water scarcity conditions alleviated in Yangtze and Yellow basins and degraded in the Indus and Ganges basins. These important findings highlight that the practical water scarcity adaptation measures should be searched in Pakistan and India to secure future food security and environmental sustainability.