Chilled Heights: Unveiling the Local Cooling Phenomenon on Mount Everest in a Warmer World

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Kathmandu, Dec. 20: Mount Everest’s weather station has been found to be recording local cooling due to the effects of glaciers, an unusual phenomenon that contradicts with the overall trend of global warming.

The findings published recently in the scientific journal Nature Geoscience shocked scientists when they revealed unexpectedly cool temperatures on the slopes of the highest peak. It goes against climate expectations and raises questions about the unique climate dynamics of Mt. Everest.

Altogether 19 scientists from different parts of the world, including Dr. Sudeep Thakuri, Associate Professor at Tribhuvan University, Nepal, uncovered the unexpected phenomenon that differs from the global warming story, shedding light on a unique glacier effect on local temperature.

The study team was led by Dr. Franco Salerno from Italy’s National Research Council in Milan.

The team had used hourly temperature data since 1994 at the Lobuche Pyramid International Laboratory–Observatory (Pyramid Lab) on Mt. Everest’s slopes, situated at an altitude of 5,035 metres above sea level. This station has the longest weather dataset at elevations that support glaciers.

Dr. Thakuri, who is also a thematic expert in climate change and water, said that the research team observed a significant shift in weather patterns about 15 years ago, with maximum summer temperatures decreasing at a rate of about 0.04 degrees Celsius per year. This trend was consistent with observations from other nearby weather stations at higher elevations, which also indicated a cooling pattern during summer time, he added.

According to Dr. Thakuri, in the study, data was used not only from Pyramid Lab, but also from the other five weather stations from the Tibetan side and the climate reanalysis to observe the regional trends more comprehensively.

“We acknowledge the global temperature rise, but there’s hope that certain regions with preserved local glaciers are cooling. This trend is not only observed in Nepal but also in the eastern and western parts of the Himalayas where glaciers are preserved,” he said.

“The cooling effect is attributed to warmer temperatures at higher elevations, where glaciers exchange heat with the atmosphere. This exchange triggers instability, causing the air above glaciers to cool and flow downhill, resulting in a cooling effect around the Pyramid Lab and its surroundings,” Dr. Thakuri informed.

According to Dr. Thakuri, this unique mechanism may temporarily counteract some of the effects of global warming in glacier regions. The findings highlight the complexity of climate dynamics, emphasising the need for ongoing research to fully understand the interplay of factors influencing temperature trends worldwide.

The study unveils a previously unnoticed process in the interaction between glaciers and climate at high elevations. It highlights a glacier-induced effect on local temperature associated with global warming, leading to a daytime temperature decrease near the glacier masses. The research, focusing on

the Himalayas, suggests the potential widespread occurrence of similar glacier effects in mountain chains globally.

The proposed model helps explain why we are seeing both local cooling and increased melting of glaciers in the Himalayas, Thakur said. “Though the air higher up is getting warmer, the study found that the air right above the glacier surface is getting cooler. This cooling effect boosts downhill winds, affecting lower glacier areas and the surrounding land where the glacier melts.”

Unexpectedly, the local cooling not only protects lower glacier areas from warming but also brings down the point where winds from different directions meet. This leads to less rainfall at higher elevations, negatively affecting the balance of glacier mass.

The study also highlights potential effects on mountain ecosystems, as increased cooling in early warm seasons may influence snowmelt rates and extend the snow season

While the study focused on the Himalayas, the research highlighted the process may be globally relevant.

“Future investigations should explore its existence in other regions and consider morphological and climatic factors controlling it, calling for expanded research to comprehend the factors determining katabatic processes (wind that carries high-density air from a higher elevation down), their cooling impact, and their ability to alter glacier mass balance across diverse climates and regions,” according to Dr. Thakuri.

Source: The Rising Nepal