Physical and biogeochemical responses of Tibetan Plateau lakes to climate change

Abstract

The lakes, rivers and glaciers of the Tibetan Plateau (TP) — a vital water resource for East Asia — are undergoing substantial environmental change. In this Review, we examine trends in the size and the physical and biogeochemical properties of TP lakes. Lake area and volume have consistently increased since 1995, with most rapid expansion in northern lakes. Between 1986 and 2022, the total area of lakes larger than 1 km2 increased from 37,109 km2 to 46,980 km2, and water storage increased by 169.7 km3, driven by warming and enhanced precipitation. In large lakes (≥10 km2), average surface temperatures increased by 1.33 °C, water transparency increased by 1 m, and salinity decreased from 48.76 to 23.76 psu. Responses in lake biogeochemistry include enhanced microbial diversity and trophic status, despite minimal additional nutrient inputs and consistent rates of productivity. Although TP lakes appear to be a net source of CO2 to the atmosphere (1.60, 6.87 and 1.16 Tg C yr−1 in the 2000s, 2010s and the 2020s, respectively), long-term CO2 source-sink dynamics remain uncertain. TP lake area is projected to increase by 9,000 km2 by 2050 under SSP5-8.5 and will continue to influence and enhance regional precipitation. Improved prediction of TP lake hydrology and biogeochemistry will aid sustainable management of water resources across the TP. Climate change affects Tibetan lakes through its influence on precipitation, glacial meltwater flux, and permafrost degradation. This Review discusses the observed response of the physical and biogeochemical properties of lakes, including salinity and trophic complexity, to changes in lake size and looks towards future priorities in lake monitoring and modelling.