Srinagar, Aug 19: The western Himalaya, including Jammu & Kashmir, Ladakh and Himachal Pradesh could see winter temperatures rise by as much as 7.18°C by the end of this century, while spring snow loss could reach 95.9 kg per square metre under a high-emission scenario, according to a new study.
The projections place the western Himalayan sector ahead of the central and eastern Himalaya in both warming and snow loss, with researchers finding that the region consistently emerges as the most climate-sensitive of the three sectors examined.
What makes the projections particularly stark is the difference between the possible futures: if emissions are sharply reduced, western Himalayan winter warming by the end of the century is projected at 2.55°C. If emissions remain high, it rises to 7.18°C, a difference of about 4.6°C.
The study, published in the Journal of Earth System Science, draws on 120 years of observed temperature data, from 1901 to 2020, and eight global climate models to assess changes in temperature and snow across the Indian Himalayan region through 2100.
The projections are not based only on what may happen decades from now. The researchers found that the Himalayan region has already warmed by close to 1°C compared with the first three decades of the 20th century.
In winter, the western Himalaya had warmed by 1.06°C by the period up to 2014, compared with 0.96°C in the central Himalaya and 1.09°C in the eastern Himalaya.
The western sector recorded an even stronger warming signal in spring, with temperatures rising 1.08°C, against 0.83°C in both the central and eastern Himalaya.
The researchers noted that warmer-than-normal years have increasingly become the norm across the three sectors over the past two to three decades, with much of the observed warming occurring in recent years.
“The western Himalaya consistently emerges as the most sensitive stretch — it warms the most and loses the most snow under every pathway we tested. That has direct consequences for the states that sit in it,” said Protyusha Mukhopadhyay, lead author of the study.
The study projects that the west-east gap will become more pronounced during the century.
Under the high-emission pathway, winter temperatures during 2081–2100 could be 7.18°C higher in the western Himalaya, compared with 6.71°C in the central Himalaya and 5.82°C in the east, relative to the early-20th-century baseline.
Spring temperatures in the western sector could rise by 6.91°C, compared with 6.41°C in the central Himalaya and 5.16°C in the eastern Himalaya.
The researchers said the faster warming of winter is particularly important because winter is the season when snow is expected to accumulate.
“Less snow on the ground would mean a darker surface, which absorbs more heat, which melts more snow,” said Parthasarathi Mukhopadhyay, corresponding author of the study.
The snow projections provide another measure of how sharply the western Himalaya could change.
The study projects that, under the lowest-emission pathway, spring snow in the western Himalaya could decline by 24.2 kg per square metre by 2040, 27.4 kg by 2060 and 32 kg by the end of the century.
Under the highest-emission pathway, however, the projected decline by the end of the century rises to 95.9 kg per square metre.
The researchers said the latter figure points towards an almost complete loss of seasonal snow in some pockets of the region.
The central Himalaya is projected to lose between 17.0 and 34.9 kg per square metre of spring snow by century-end, depending on the emissions pathway, while the eastern Himalaya’s projected loss ranges between 5.5 and 11.1 kg.
Winter snow loss in the western Himalaya is projected to range from 9.5 kg per square metre under the lowest-emission pathway to 53.2 kg under the highest.
Another finding could have implications for the region’s snowpack: night-time temperatures are rising faster than daytime temperatures across the western Himalaya.
Winter minimum temperatures in the western sector have risen by 1.23°C, compared with 0.87°C for maximum temperatures.
In spring, the corresponding increases are 1.25°C and 0.91°C.
The pattern is important because colder nights allow snow and ice to refreeze. Warmer nights reduce that recovery period and can alter the timing of snowmelt and the arrival of meltwater downstream.
“Rising night-time temperatures are the quieter half of this story, and arguably the more consequential one,” said Swagata Payra, a co-author of the study.
The study finds that the climate futures remain relatively similar over the next two to three decades, but begin to diverge considerably later in the century.
For western Himalayan winters, the difference between a low-emission and high-emission pathway is 4.6°C by century-end.
For spring snow, the high-emission pathway produces roughly three times the loss projected under the low-emission pathway. For winter snow, the difference is more than five times.
“The models agree on where we are headed over the next two to three decades. What remains open is the second half of the century, and that is determined by emissions,” Mukhopadhyay said.
The three Himalayan sectors covered by the research contain more than 15,000 glaciers and feed the Indus, Ganges and Brahmaputra river systems, on which roughly 1.5 billion people depend.
The researchers, however, caution that models still do not adequately capture how water moves through the high mountains. They have called for stronger ground and satellite monitoring, high-resolution modelling, early-warning systems, sustainable water management and region-specific climate adaptation measures.
