Dynamic Response of Glaciers in the Qilian Shan to Climate Change (Dyn-Q)

点击翻译按钮获取中文摘要

Knowledge on glacier and melt water variability is crucial for sustainable water supply in Central Asia since they function as water towers for millions of people. The Qilian Shan, are located in the most Northeastern part of the Tibetan Plateau, on the border between Qinghai and Gansu Province in China provide important water resources to nourish peripheral areas, especially the Hexi Corridor, which is the most important agricultural area in Northwest China. In recent decades, along with increasing air temperature and the desertification of Hexi Corridor, glaciers in Qilian Mountain, especially in the middle and east part, experience rapid mass wastage. Glaciers in these mountain areas are important elements of the natural environment forming water resources of cardinal importance both for ecosystems and local population. Glaciers in Qilian Shan are mostly summer-accumulation-type glaciers, being reported to be vulnerable to the current global warming trend and are experiencing rapid shrinkage due to feedback mechanisms. The main objective of the proposal Dynamic Response of Glaciers in the Qilian Shan to Climate Change (Dyn-Q) is to improve the understanding of atmosphere-cryosphere coupling in the Qilian Shan by modelling the temporally integrated variations in glacier flow patterns and geometry due to atmospheric forcing, including variations in energy and mass balance components induced by climate change and their impact on regional water resources. Main feedback mechanisms within energy balance are that the increase in air temperature during the melting season triggers both the increase in glacier ice temperatures resulting in changed flow patterns and the reduction of albedo at the glacier surface, especially during the summer season due to a phase change of precipitation from solid to liquid. Within Dyn-Q we propose the direct coupling of flow dynamics and surface energy and mass balance modelling over periods of decades to provide much more precise response patterns that comprise all relevant physical processes. This approach necessitates coupling a three dimensional ice flow model with a physical energy and mass balance model. We hypothesize that coupled modelling of the glacier response to varying climate forcing can be much more pronounced than would be anticipated from either using only degree-day approaches combined with an ice flow model or physical climatic surface energy mass balance modelling but neglecting ice dynamics. Within Dyn-Q we will reconstruct the evolution of two benchmark glaciers in the Qilian Shan over the period of remote sensing (1980-2010) using two coupled models that account for ice dynamics and surface energy and mass balance. The aim is to evaluate the current sensitivity of these glaciers to climate change and to project the evolution of their geometry and contribution to local water resources in coming decades using the coupled model chain to be established within Dyn-Q.