An Assessment of Glacial Contributions to Lake Dynamics across the Tibetan Plateau since the Late Pleistocene

Abstract:

The Tibetan Plateau is one of the world’s most vulnerable areas to global warming, and is home of the world’s largest group of mountain glaciers and high-altitude lakes. These lakes in general have shrunk significantly since the late Pleistocene, and are currently continuing to experience changes in their distribution and inundation area. In the meantime, Tibetan glaciers have also gone through dramatic changes as evidenced by paleo glacial relics and recent accelerated melting. The paper provides a regional-scale systematic assessment of both paleo and contemporary lake changes across the plateau using geo-spatial information and optically stimulated luminescence (OSL) dating technologies. Using high-resolution satellite imagery of the plateau together with topographic data, this research recovered paleo lake extents for hundreds of contemporary lakes with visible paleo shore relics and estimated the amount of paleo lake shrinkage at regional scales. Both the basin-based water mass balance analysis using glacier/lake sizes and OSL dating of paleo shores suggest that paleo glaciers played a crucial role in the observed paleo lake shrinkage. Recent ~40 year lake dynamics was monitored by tracking thousands of Tibetan lakes using hundreds of satellite images. The results reveal that the overall total lake area has increased by ~26% between 1976 and 2009. The detected lake dynamics exhibit a strong spatial pattern generally but with local variations. The climate change and its regional glacier variations explain the general trend and the regional patterns of lake dynamics, respectively. The glacier mass monitored by GRACE satellites suggests a thinning trend over the past 12 years in the south while a gaining along the northern rim of the plateau. Basin-based analysis identifies glacial impacts on lake dynamics and explains many local variations. It can be concluded that glaciers play an important role in detected paleo as well as recent lake changes, and will continue to play a critical role in Tibetan lake dynamics in near future.