The Himalayas are fast receding under the impacts of global warming. In contrast, the glaciers of central Karakoram have remained unchanged or even increased slightly over the last few decades – a phenomenon puzzling glaciologists and providing climate deniers with a rare straw to clutch at.
Researchers have made a significant leap towards solving the mystery of why few pockets of glaciers in the Karakoram Range are resisting glacial melt due to global warming – defying the trend of glaciers losing mass across the globe, with the Himalayas being no exception. They have attributed this phenomenon called ‘Karakoram Anomaly’ to recent revival of western disturbances over the Himalayas.
Himalayan glaciers are of paramount importance in the Indian context, especially for the millions who dwell downstream, relying on these perennial rivers for their day-to-day water needs. They are fast receding under the impacts of global warming, and stifling stress on the water resources is inevitable in the coming decades.
In contrast, the glaciers of central Karakoram have remained unchanged or even increased slightly over the last few decades. This phenomenon has been puzzling glaciologists and providing climate deniers with a very rare straw to clutch at.
Climatic anomaly
Dr. Pankaj Kumar, is an associate professor at the Indian Institute of Science Education and Research (IISER) Bhopal. He was not alone in finding this phenomenon peculiar – because the behaviour seemed confined to a very small region, with only Kunlun range being another example of showing similar trends in the entire Himalayan range.
A recent study he has conducted explains this defiance of the impacts of global warming in certain pockets as opposed to other glaciers of the region.
In a paper published in the American Meteorological Society’s Journal of Climate, Pankaj Kumar and his group claims that the recent revival of western disturbance (WD) has been instrumental in triggering and sustaining the Karakoram Anomaly since the advent of the 21st century. The study was supported by the Climate Change Programme of the Department of Science and Technology.
It is for the first time that a study brought to the front the importance that enhanced WD-precipitation input during the snow accumulation period plays in modulating the regional climatic anomaly.
Role of snowfall
Aaquib Javed, a Ph.D scholar working under Kumar and lead author of the study says that “Westerly disturbances are the primary feeder of snowfall for the region during winters. Our study suggests they constitute about around 65 per cent of the total seasonal snowfall volume and about 53 per cent of the total seasonal precipitation, easily making them the most important source of moisture.” Javed points out that “the precipitation intensity of westerly disturbances impacting Karakoram has increased by around 10 per cent in last two decades, which only enhances their role in sustaining the regional anomaly.”
The group applied a tracking algorithm (developed at the University of Reading) to three separate global reanalysis datasets to track and compile a comprehensive catalogue of westerly disturbances impinging the Karakoram-Himalayan region over the past four decades. The analysis for the tracks passing through the Karakoram reveals the role of snowfall as a crucial factor in mass balance estimations.
Ray of hope
This is the first time that the impact of precipitation in feeding the anomaly has been highlighted. Previous studies highlighted the role of temperature in establishing and sustaining the anomaly over the years. Researchers have also quantified the impact of precipitation in feeding the anomaly.
Calculations by the scientists reveal that contribution of westerly disturbances, in terms of snowfall volume over the core glacier regions of Karakoram have increased by about 27 per cent in recent decades. In the meanwhile, precipitation received from non-WD sources have significantly decreased by around 17 per cent, further strengthening their claims.
“The anomaly provides a very bleak (prognosis), but nonetheless a ray of hope towards delaying the inevitable,” says Dr Kumar. “After recognising the importance of WDs in controlling the anomaly, their future behaviour might very well decide the fate of Himalayan glaciers as well,” he points out.
Image: Wikimedia – The Kulum range.
