The glaciers of Central Asia have long resisted the melting observed elsewhere in the world. These ice giants, nicknamed "the third pole", now appear to be weakened by a recent change in their environment.
Since 2018, observations show an acceleration of ice melt in the Pamir Mountains of Tajikistan. Initial evidence suggests that this melting is directly linked to a sharp decrease in snowfall. This development worries scientists, as it not only threatens the water supply of millions of people, but could also alter regional and even global climate balances.
The end of an "anomaly"
For decades, some glaciers in the Pamir and Karakoram ranges have resisted global warming. This phenomenon, called the "Pamir-Karakoram anomaly", has long been a mystery to researchers. The exceptional stability of these glaciers is explained by their semi-arid environment and their significant snow cover, which partially protected them from melting.
The establishment of a monitoring station on the Kyzylsu glacier, at an altitude of 3,400 meters (11,150 feet), has made it possible to collect new precise data. The records cover the period 1999-2023 and have been combined with climate models to better understand the changes. They show that the glacier reached a critical threshold around 2018, with a marked decrease in snow cover.
The immediate consequence is an accelerated melting of the glacier. This change affects the health of the ice and the regulation of watercourses, highlighting that the "anomaly" observed for decades could be coming to an end. However, the exact origin of the reduction in precipitation remains uncertain and may not be solely related to global warming.
Observations and local implications
Scientists had to overcome the isolation and political instability of the region to install their instruments. Since 2021, they have been collecting detailed data on snow and water flow, which has made it possible to reliably model the behavior of the glacier.
Local communities, such as the shepherds of the Pamir, actively participate in the observations. They report changes observed on the ground, confirming the acceleration of melting and providing valuable feedback for researchers. This collaboration strengthens the measurements and makes it possible to maintain monitoring despite logistical difficulties.
The Kyzylsu feeds the Amu Darya basin, a river essential for agriculture and the local ecosystem. Although increased melting temporarily provides more water, the future remains worrying, as the decrease in snow cover gradually reduces the glacial reserves available for downstream populations.
Article author: Cédric DEPOND