Scientists solve the curious case of Himalayan glaciers resisting global warming
Researchers
have taken a significant leap toward 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 (WDs).
Himalayan
glaciers are of paramount importance in the Indian context, especially for the
millions of dwellers living downstream who rely 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
surprisingly remained unchanged or slightly increased in the last few decades.
This phenomenon has been puzzling glaciologists and providing climate deniers
with a very rare straw to clutch at.
Dr Pankaj Kumar, Associate Professor at the Indian
Institute of Science Education and Research (IISER) Bhopal, found this peculiar
because the behaviour seems to be confined to a very small region, with only
Kunlun ranges being another example of showing similar trends in the whole of
Himalaya.
A recent study conducted under his supervision has
postulated a new theory to explain 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, his group claimed that
the recent revival of western disturbance 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 forth the importance that enhanced
WD-precipitation input during the accumulation period plays in modulating
regional climatic anomaly.
Aaquib Javed, a PhD student of Dr Kumar and lead author
of the study, said, “WDs are the primary feeder of snowfall for the region
during winters. Our study suggests they constitute about around 65% of the
total seasonal snowfall volume and about 53% of the total seasonal
precipitation, easily making them the most important source of moisture. The
precipitation intensity of WDs impacting Karakoram has increased by around 10%
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 catalog of WDs
impinging the Karakoram-Himalayan region in the last four decades. The analysis
for the tracks passing through the Karakoram reveals the role of snowfall as a
crucial factor in mass balance estimations.
While previous
studies have highlighted the role of temperature in establishing and sustaining
the anomaly over the years, it is for the first time that the impact of
precipitation in feeding the anomaly has been highlighted. The researchers have
also quantified the impact of precipitation in feeding the anomaly.
Calculations by the scientists reveal that contribution
of WDs in terms of snowfall volume over the core glacier regions of Karakoram
have increased by about 27% in recent decades, while precipitation received
from non-WD sources have significantly decreased by around 17%, further
strengthening their claims.
“The anomaly provides a very bleak but nonetheless a ray
of hope towards delaying the inevitable. After recognising the importance of
WDs in controlling the anomaly, their future behaviour might very well decide
the fate of Himalayan glaciers as well,” Dr. Kumar pointed out.
Publication link: https://doi.org/10.1175/JCLI-D-21-0129.1