LONDON: Glaciers nestling under the shadow of Diran and Rakaposhi, two towering peaks in the Karakoram Range of northern Pakistan, remain impervious to global warming and have even grown slightly in recent years, suggests a new study.
Bucking regional and global trends that indicate ice loss, French glaciologists have confirmed that glaciers in Himalayan Karakoram have remained impervious to global warming and climate change.
The results have implications for local water supplies and glacial hazards and, the team says, underscore the value of high resolution monitoring in accurately determining regional scale glacial changes, the journal Nature Geoscience reports.
Additionally, the results “show that we need to be careful as glaciologists when we are extrapolating measurements made on a few small glaciers”, says Etienne Berthier, glaciologist at the Universite de Toulouse in France and study co-author.
Berthier says the next plan is to take a closer look at regional climate models and meteorological data “to better understand the origin of this anomaly”, according to a Toulouse statement.
They also hope to expand their geodetic surveying to the rest of the Himalayas, which, he says, would provide a “comprehensive and consistent dataset to really look at the difference between glaciers”.
Using spaceborne data to study a 5,615 sq km section of the Karakoram Range of northern Pakistan and western China, the researchers found an increase in ice thickness of 0.11 (plus or minus 0.22) metres of water equivalent (w.e.) per year between 1999 and 2008.
Although small in magnitude, the value is significant because it diverges from best estimates of glacial ice volume change globally and over the entire Himalayan mountain range, which suggest a loss of about 0.4 to 0.8 metres per year.
Given the uncertainty in the measurement, “it’s not 100 percent sure” that there was really a mass gain, says Tobias Bolch, glaciologist at the University of Zurich in Switzerland.
But, says Bolch, who was not involved in the study but co-authored a recent review article on the current state of Himalayan glaciers in the journal Science, “what is clear is there is no significant mass loss”.
The results imply that the Karakoram glaciers might have lowered global sea levels over the period studied, albeit by only 0.006 mm per year. But previous estimates assuming the Karakoram glaciers had behaved like others in the Himalayas that had been better characterized suggested that their expected ice loss would have raised sea level by roughly 10 times as much.