Linkages of the dynamics of glaciers and lakes with the climate elements over the Tibetan Plateau

Abstract

Future climate warming is expected to have a significant effect on the operation of Earth and Ecological systems. A key concern in the future is water resource availability. In regions such as the Tibet Plateau (TP) lakes and glaciers appear to be highly sensitive to climate forcing and variations in the size and extent of these system will have profound socio-economic and environmental consequences in South and Central Asia. Although the variety of glaciers and lake son the TP is a heavily researched and discussed topic the interaction between glaciers/lakes and climate change has not be thoroughly investigated. Here we present, through a review of existing studies and original remote sensing analysis, a reconstruction of changes in the spatial coverage of glaciers and lakes on the TP from 1990 to 2015 along with an analysis of climate data for the same period. The results revealed that these systems responded to changes in both temperature and precipitation but the nature of this response, and the controlling factor, was spatially diverse. During this interval the total number of lakes increased from 868 to 1207, thus a large number of new lakes (n = 339) formed. The total water surface area of the lakes increase from 38,823.3 km2 in 1990 to 48,793.0 km2 in 2015, at a rate of 383.5 km2 yr-1. Over this period intensive glacial shrinkage occurred, primarily driven by increasing average temperature, except in the Karakoram Mountains where a slight increase in glacier extent was explained by low and stable temperatures along with increasing precipitation. The expansion of lakes in the central and northeastern TP can, therefore, be explained by a trend of increasing precipitation and the accelerated melting of glaciers associated with rising temperatures, both of which contributed to the enhanced total basin runoff. The shrinkage of lake areas along the Himalayan Mountains is accounted for by low precipitation coupled with high evaporation and limited basin space. The lakes within the Qaidam Basin express a complex pattern of response in association with fluctuating precipitation and strong evaporation. The pattern of shrinking glaciers and expanding lakes indicate that water-cycle processes on the TP have been accelerating during the past 25 years. Under current climates, and future climate change, the shrinkage of glaciers and the enlargement of lakes may be expected to continue to accelerate until a “tipping point” is reached when the meltwater of declining glaciers can no longer sustain the enhanced lake levels. Such a scenario would have severe socio-economic and ecological consequences for this region making the continued study of water-cycle activity across the TP an urgent priority.