Himalayas lost glaciers equal to weight of 570 million elephants in 20 years

Researchers have for the first time documented the mass loss of glaciers in the Himalayas that had remained invisible as it was happening below the surface of the glacier. The glaciers have lost enough mass equal to around 570 million elephants put together.

The lake-terminating glaciers have been underestimated due to the inability of satellites to see glacier changes occurring underwater. This loss was not considered by previous studies as the utilized satellite data can only measure the lake water surface but not the ice underwater replaced by water.

The study published in the journal Nature Geoscience the largest underestimation occurred in the central Himalayas, where glacial lake growth has been the most rapid.

“Our estimates reduce uncertainties in total glacier mass loss, provide important data for glacio-hydrological models, and therefore also support the water resources management in this sensitive mountain region,” researchers said in the paper. A particularly interesting case is Galong Co in this region, with a high underestimation of 65%.

“These findings have important implications for understanding the impact of regional water resources and glacial lake outburst floods. By accounting for the mass loss from lake-terminating glaciers, we can more accurately assess the specific annual mass balance of these glaciers compared to land-terminating ones, which further highlights the accelerated glacier mass loss across the greater Himalaya,” lead author Guoqing Zhang from the Institute of Tibetan Plateau Research, said in a statement.

From 2000 to 2020, proglacial lakes in the region increased by 47 per cent in number, 33 per cent in area, and 42 per cent in volume. This expansion resulted in an estimated glacier mass loss of around 2.7 Gt equivalent to 570 million elephants or over 1000 times the total number of elephants living in the world.

Researchers highlighted the need to understand the mechanisms driving glacier mass loss and the underestimated mass loss of lake-terminating glaciers globally.

“In the long run, we expect mass loss from lake-terminating glaciers to continue being a major contributor to total mass loss throughout the twenty-first century as glaciers with significant mass loss may disappear more rapidly compared to existing projections,” David Rounce, co-author from Carnegie Mellon University said.