The quantitative attribution of climate change to runoff increase over the Tibetan Plateau

Runoff from the Tibetan Plateau (TP), known as the Asian water tower, is crucial to regional hydrological processes and the availability of water for large population living downstream. Climate change, especially marked atmospheric warming and altered precipitation patterns, have significantly affected the cryospheric hydrological process in the TP, particularly runoff. However, it is still unclear to what extent precipitation and temperature contribute to runoff change on the TP and the regional variability is not well understood. In this study, a large-scale, high-resolution, and well-calibrated distributed hydrological model was employed to simulate the long-term runoff of the TP over the past six decades (1961-2019). Then, spatiotemporal characteristics of runoff were analyzed. Furthermore, the impacts of precipitation and temperature on runoff variation were quantitatively estimated. The results found that the annual runoff decreased from southeast to northwest, and has been increasing over the past six decades. Notably, precipitation is a more important contributor than temperature across the plateau, contributing 72.08 % and 27.92 % to the runoff change, respectively. Besides, the influence of precipitation and temperature on runoff varies among basins, with the Daduhe Basin and the Inner Basin being the most and least influenced by precipitation, respectively. This research analyses historical runoff changes and provides insights into the contributions of climate change to runoff on the TP, which helps understand the hydrological response to climate change in mountain regions.