Constantly renewing glacial lakes in the Kyrgyz Range, northern Tien Shan

Abstract. Glacial lakes in the Kyrgyz Range of the northern Tien Shan, Kyrgyz Republic, Central Asia are monitored due to concern over possible glacial lake outburst floods (GLOFs) after recent glacier shrinkage in the area. To evaluate the status of these lakes, we investigated the number of glacial lakes and the lake area from 1968 to 2021 using Corona KH-4, Landsat (7 to 10), Sentinel-2, and PlanetScope satellite images. We found that the number of glacial lakes increased by 30 % from 417 in 1968 to 543 after 2000. However, some lakes vanished. In particular, 305 of the original 417 glacial lakes vanished by 2000, whereas 431 of the 543 glacial lakes identified between 2000 and 2021 formed after 2000. In addition, the total lake area significantly increased from 0.87 km² in 1968 to 5.21 km² in 2021. New glacial lakes rapidly formed because the glacier area has decreased by 32 % over the past 50 years, and the places from which glaciers retreated have changed into glacier-moraine complexes (GMCs) on which new lake basins appeared and expanded. Thus, the renewal of glacial lakes in the Kyrgyz Range is the outcome of glacier shrinkage and ice melting within GMCs.