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Glaciers in the Himalayas are melting fast, but a new report has revealed that a remarkable phenomenon in the world’s highest mountain range could help mitigate the effects of the global climate crisis.
When warming temperatures hit certain high-altitude ice masses, it sets off a surprising reaction that blows strong cold winds down the slopes, according to the study published Dec. 4 in the journal Nature Geoscience.
The warming climate creates a larger temperature gap between the surrounding air above the Himalayan glaciers and the cooler air that is in direct contact with the surface of the ice masses, explained Francesca Pellicciotti, professor of glaciology at the Institute of Science and Technology of Austrian and lead author of the study. .
“This results in increased turbulent heat exchange at the glacier surface and stronger cooling of the surface air mass,” she said in a news release.
As the dry, cool surface air becomes cooler and denser, it sinks. The air mass flows down the slopes into the valleys, creating a cooling effect in the lower areas of the glaciers and neighboring ecosystems.
With ice and snow from the mountain range feeding into 12 rivers that provide fresh water to nearly 2 billion people in 16 countries, it is important to know whether the Himalayan glaciers can maintain this self-preserving cooling effect and the region facing a likely rise. in temperature in the next few years.
Melting glacier
A June report previously covered by CNN showed that glaciers in the Himalayas melted 65% faster in the 2010s compared to the previous decade, suggesting that rising temperatures are already having an impact in the area.
“The main impact of rising temperatures on glaciers is an increase in ice loss, due to increased melting,” said Fanny Brun, a research scientist at the Institut des Géosciences de l’Environnement in Grenoble, France. She was not involved in the study.
“The main mechanisms are the lengthening and intensification of the molting season. They form glaciers that thin and retreat, resulting in deglaciated landscapes that tend to further increase air temperatures due to (go). absorb more energy at the surface,” said Brun.
That absorption of energy at the surface is determined by something called the albedo effect. Light or “white” surfaces such as clean snow and ice will reflect more sunlight (high albedo) compared to “dark” surfaces such as land exposed when glaciers, soil and oceans disappear (low albedo). In general, Brun said this phenomenon is interpreted as a positive feedback loop, or a process that improves change, but overall is poorly studied and difficult to quantify.
At the base of Mount Everest, however, it seemed strange that measurements of the overall average temperature were stable instead of increasing. Close analysis of the data revealed what was really happening.
“While the minimum temperatures have been steadily increasing, the maximum summer surface temperatures have been steadily falling,” said Franco Salerno, co-author of the report and a researcher for Italy’s National Research Council, or CNR.
However, even these cooling winds are not enough to fully combat the rising temperatures and melting glaciers due to climate change. Thomas Shaw, who is part of the ISTA research group with Pellicciotti, said that the reason for these glaciers melting quickly is however complex.
“The cooling is local, but it may not be enough to overcome the greater impact of climate warming and fully preserve the glaciers,” said Shaw.
Pellicciotti explained that the general lack of data in high-altitude areas around the globe led the study team to focus on using unique ground observation records at one station in the Himalayas.
“The process we highlighted in the paper could be globally relevant and could happen on any glacier in the world where conditions are met,” she said.
The new study provides a strong impetus to collect more high-altitude, long-term data that is desperately needed to prove the new findings and their broader implications, Pellicciotti said.
Data warehouse
Located at a glaciated elevation of 5,050 meters (16,568 feet), the International Pyramid Laboratory/Observatory climate station is located along the southern slopes of Mount Everest. The observatory has recorded detailed meteorological data for almost 30 years.
It is those granular meteorological observations that Pellicciotti, Salerno and a team of researchers used to conclude that warming temperatures are fueling what are known as katabatic winds.
The cold winds, which create air flowing downhill, usually occur in mountainous regions, including the Himalayas.
“Katabatic winds are a common feature of Himalayan glaciers and their valleys, and have probably always occurred,” Pellicciotti said. “However, what we observe is a significant increase in the intensity and duration of katabatic winds, and this is due to the fact that the temperature of the surrounding air has increased in a warming world.”
Another thing the team noticed was ground-level ozone concentrations associated with lower temperatures. This evidence shows that katabatic winds work as a pump that can transport cold air from the higher elevation and the atmospheric layers down to the valley, explained Pellicciotti.
“According to the current state of knowledge, Himalayan glaciers are doing better than average glaciers in terms of mass loss,” said Brun.
Glacier loss in Asia vs Europe
Brun explained that the glaciers in the Central Himalaya have thinned, on average, by about 9 meters (29.5 feet) in the past twenty years.
“This is much lower than glaciers in Europe, which have thinned about 20 meters (65.6 feet) over the same period of time, but this is more than other regions in Asia (for example in the Karakoram region), or in the Arctic region,” said Brun.
How long these glaciers are able to cope locally with the impacts of global warming may be critical to effectively addressing our changing world.
“We believe that katabatic winds are the response of healthy glaciers to global warming and that this phenomenon could help preserve the permafrost and the surrounding vegetation,” said study co-author Nicolas Guyennon, a researcher at the National Council for Research in Italy.
However, further analysis is needed. The aim of the study team is to identify the glacial characteristics that favor the cooling effect. Pellicciotti said that more long-term ground stations to test this hypothesis elsewhere are almost absent.
“Even if the glaciers can’t preserve themselves forever, they may preserve the environment around them for a while,” she said. “Therefore, we call for a more multidisciplinary research approach to bring together efforts to explain the effects of global warming.”
A separate report in 2019 found that even in the most optimistic scenario, in which average global warming was limited to 1.5 degrees Celsius (2.7 degrees Fahrenheit) above pre-industrial temperatures, the Himalaya region would lose at least one-third of its glaciers.
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