Recent research shows that the mass loss of lake-terminated glaciers in the Himalayas has been greatly underestimated, due to the limitations of satellites in detecting underwater changes in glaciers. This has important implications for the region’s future projections of glacial loss and water resources.

The research was published in the journal Nature Geology Chinese Academy of Sciences, Graz University of Technology in Austria, St. Andrews University and the global collaboration of scientists from Carnegie Mellon University in the United States. situation

The researchers found that the previous estimate underestimated the total mass loss of lake-terminating glaciers in the Greater Himalayas by 6.5%. The most significant underestimate of 10% occurred in the central Himalayas, where glacial lake growth was fastest. The example of Galong Co is of particular interest in this region, with an overestimation of 65%.

This surveillance was largely due to the limitations of satellite imagery in detecting underwater changes, leading to an information gap in our understanding of the full extent of glacier loss. From 2000 to 2020, the number of preglacial lakes in the region increased by 47%, their area increased by 33% and their volume by 42%. This expansion resulted in a loss of glacial mass of about 2.7 Gt, equivalent to 570 million elephants, or more than 1,000 times the total number of elephants in the world. This loss was not explained in previous studies because the satellite data used can only measure the water surface of the lake, but not the underwater ice that has been replaced by water.

“These findings have important implications for understanding the impact of flooding from regional water sources and glacial lakes,” said lead author Zhang Guoqing of the CAS Tibetan Plateau Research Institute.

By accounting for the mass loss of lake-end glaciers, the researchers can more accurately predict the annual mass balance of these glaciers compared to land-end glaciers, further emphasizing the accelerated mass loss of glaciers in the Greater Himalayas.

The study also highlights the need to understand the mechanisms that cause glacial mass loss and the underestimated global loss of lake-terminated glacier mass, which is estimated to be about 211.5 Gt, or about 12%, between 2000 and 2020.

“This highlights the importance of including underwater mass loss from lake-terminated glaciers in future mass change estimates and glacier evolution models, regardless of study region,” said corresponding author Tobias Bolch, from the Graz University of Technology.

Co-author David Rawnes at Carnegie Mellon University noted that as glaciers with significant mass loss may disappear, over the long term, mass loss from lake-terminated glaciers may continue to be the main driver of total mass loss in the 21st century. . faster than current estimates.

“With a more accurate account of glacial mass loss, researchers will be able to better predict the future availability of water resources in a sensitive mountainous region,” said co-author Yao Tandong, co-chairman of the Third Polar Circle (TPE). ), an international science program for interdisciplinary research on the relationships between water, ice, climate and humanity in the region and beyond.