Himalayan glaciers react, blow cold winds down their slopes

Himalayan glaciers react, blow cold winds down their slopes
by Robert Schreiber
Berlin, Germany (SPX) Dec 05, 2023

An international research team, led by Professor Francesca Pellicciotti of the Institute of Science and Technology Austria (ISTA), has unveiled a remarkable response of Himalayan glaciers to global warming. Published in Nature Geoscience, their study shows that these glaciers are cooling the air around their surfaces, producing cold winds that may help in preserving the glaciers themselves and the surrounding ecosystems.

The Unexpected Stability of Temperatures at Mount Everest
Initially, scientists observed an elevation-dependent warming effect in mountainous regions, where peaks experienced accelerated warming. However, data from a high-altitude climate station at the base of Mount Everest in Nepal presented an anomaly: surface air temperature averages remained stable, defying expectations of a rise. This observation sparked curiosity among researchers.

Decoding Glacier Responses at Pyramid International Laboratory/Observatory
Located at 5050 meters on the southern slopes of Mount Everest, the Pyramid International Laboratory/Observatory has been a critical site for understanding these phenomena. Here, researchers, including Professor Pellicciotti and CNR's Franco Salerno and Nicolas Guyennon, observed a counterintuitive process. They noted that while minimum temperatures rose steadily, the summer surface temperature maxima were dropping. This was attributed to the glaciers increasing their temperature exchange with the surface air, intensifying turbulent heat exchange and subsequently cooling the air mass in contact with the glacier.

Understanding the Katabatic Winds Across the Himalayas
Beyond ground observations, the team employed ERA5-Land reanalysis, a global climate model, to confirm that this cooling effect, characterized by katabatic winds, was not limited to Mount Everest but prevalent across the entire Himalayan range. These winds are a direct consequence of three decades of global temperature rise. The study aims to identify key glacier characteristics that facilitate this reaction.

Glacier Stability and Environmental Preservation
The researchers are also exploring whether similar phenomena are occurring in the glaciers of the Pamir and Karakoram mountains. These areas, to the northwest of the Himalayas, are known for their stable or growing glaciers. The team hypothesizes that the flatter slopes in these regions might cause the cold winds to cool the glaciers themselves rather than affecting the surrounding environment.

Emerging Concerns: Glacier Tipping Point and Water Security
While these cooling winds might indicate a short-term defensive mechanism against global warming, they also pose long-term concerns. Glaciers in the Himalayas, which are accumulation-ablation glaciers, are experiencing a shift in the altitude at which precipitation occurs. This shift potentially reduces key mass inputs to the glaciers, thereby affecting their long-term stability. This phenomenon is crucial, as glaciers play a vital role in maintaining water security in their ecosystems.

Conclusion and Future Research
In conclusion, Professor Pellicciotti emphasizes the need for multidisciplinary research to fully understand the effects of global warming on glaciers. Although these glaciers may not preserve themselves indefinitely, their current reactions could temporarily protect the surrounding environment. This study highlights the complex and dynamic nature of glacier responses to climate change, urging further investigation into these critical natural resources.

Research Report:Local cooling and drying induced by Himalayan glaciers under global warming