Abrupt increase in thermokarst lakes on the central Tibetan Plateau over the last 50 years

Thermokarst lakes are an important ecosystem component in permafrost terrains; therefore, quantifying changes in these lakes is important for evaluating the water balance and carbon budget on the Qinghai-Tibet Plateau (QTP). In this study, we utilized high spatial resolution aerial and satellite images from 1969, 2010, and 2019 to quantify changes in thermokarst lakes > 0.1 ha across four regions on the central QTP. The results indicated an overall significant increase in the lake number (+158%) and surface area (+123%) for all study regions over the last five decades, despite variations in change in these trends among the different landform types. Changes in individual lake processes indicated that the above lake changes were mainly characterized by a significant increase in the number of small lakes and area enlargements of large lakes, whereas thermokarst lake drainage only occurred in some gentle slope areas. By analyzing the potential factors that drive changes in thermokarst lakes in the study region, we found that persistent climate warming and the increasing of precipitation were the most likely explanations for the observed results. With continued climate warming and permafrost degradation, we expect a persistent increase in the number and surface area of thermokarst lakes; however, the probability of lake drainage may also increase with lake expansion.

Automated summary

This study investigated the changes in thermokarst lakes on the Qinghai-Tibet Plateau using high spatial resolution images. The results showed a significant increase in the number and surface area of thermokarst lakes over the last fifty years, with variations in change among different landform types. The increase in small lakes and expansion of large lakes were the main changes observed, while lake drainage occurred in some gentle slope areas. Climate warming and increased precipitation were identified as the most likely factors driving these changes.