Glaciers are an important factor affecting the Earth's environment, and scientists are studying the changes in global glaciers caused by global climate change. Chinese scientists found in the second Qinghai Tibet scientific expedition that from 2000 to 2020, the loss of underwater ice mass in the Himalayan region was underestimated by approximately 2.7 billion tons. This achievement was jointly completed by the scientific expedition team of the second Qinghai Tibet scientific expedition "Dynamic Changes and Impacts of Asian Water Towers", researcher Zhang Guoqing of the Environmental Change and Multilayer Process Team of the Qinghai Tibet Plateau Institute, Chinese Academy of Sciences, and was published online in the international academic journal Nature Geoscience on April 3. Zhang Guoqing introduced that digital elevation model (DEM) is widely used to estimate the global glacier mass loss, but this method can only observe the glacier surface and water surface, and cannot reveal the glacier mass loss occurring below the water surface of the pre ice lake. The Himalayan region is home to tens of thousands of ice lakes. Against the backdrop of global warming, glaciers are accelerating their melting and retreat, and pre glacial lakes connected to glaciers are rapidly expanding, accounting for about 12% of the total number of ice lakes in the region. However, previous research has focused more on changes in ice lake area and water volume. When estimating changes in ice volume of glaciers, traditional geodetic methods have not taken into account the loss of underwater ice mass caused by ice lake expansion, resulting in significant losses in the Himalayan region The loss of glacier mass on a global scale is underestimated In this scientific examination, Chinese scientists, in collaboration with researchers from Graz University of Technology in Austria, St. Andrews University in the UK, and Carnegie Mellon University in the United States, used remote sensing data from multiple years of ice lakes to conduct detailed mapping and classification of ice lakes in the Himalayan region. Combined with underwater topographic measurement data of typical ice lakes, the water volume changes of Himalayan ice lakes were estimated in detail, Quantified the loss of glacier mass below the surface of glacial lakes caused by climate change. The research results indicate that from 2000 to 2020, the number of pre glacial lakes in the Himalayan region increased by approximately 47%, the area expanded by 33%, and the water volume increased by 42%. The increase in the water volume of ice lakes has led to an underestimation of approximately 2.7 billion tons of underwater ice mass loss in the Himalayan region from 2000 to 2020, accounting for approximately 6.5% of the total mass loss of pre glacial lakes. Among them, the central Himalayan region is the most underrated, with approximately 1.2 billion tons, accounting for 10%. Located in the Boqu River basin in the central Himalayas, Galongcuo covers an area of approximately 5 square kilometers, with a maximum depth of 200 meters and a loss of up to 65% of underwater ice mass. At the same time, the study also preliminarily estimated the global underwater ice loss in pre glacial lakes, with a loss of approximately 210 billion tons, accounting for 12% of the global total ice lake contact glacier mass loss. Zhang Guoqing said: "As the Himalayan ice lakes become larger and deeper, the underwater ice loss is still an important factor affecting the future total ice mass loss and the risk assessment of related ice lake outburst floods. Our research provides a method to quantify the underwater ice mass loss, reduces the uncertainty of estimating the total ice mass loss, provides important data for glaciology models, and more accurately simulates the past and future ice mass balance, and evaluates glaciers and ice The lake disasters and changes in water resources provide important scientific basis (Outlook New Era Network)