Bhubaneswar: Third Pole (TP) primarily receives rainfall during summer and snowfall during winter and spring as its major forms of precipitation. Changes in snow depth and precipitation in the TP pose a serious threat to the socioeconomic sustainability in South Asia region, revealed a recent study.

TP is Earth’s largest highland area holding vast reserves of glacier ice and snow cover. These resources are crucial for sustaining the flow of water that supports South Asia’s water security and socioeconomic stability, nourishing three major Asian rivers — the Indus, Ganga, and Brahmaputra — which depend on snowmelt water from the Central Himalayas.

Winter snow depth reaches ≥1 m deep, while in summer it reduces to ≤0.2 m. During spring, the central and western Himalaya and Karakoram ranges often experience an elevated snowmelt and snow water equivalent. These are the regions with most glaciers in the TP, the study stated.

Snowmelt in the western Himalaya during spring is on the rise (>0.5 × 10−3 mm yr−1), aligning with the observed temperature increase (0.04–0.06 °C yr−1) in the region. Additionally, there has been a noticeable increase in the annual mean glacier melt in TP, with water equivalent thickness decreasing by -1 to -5 cm w.e. yr−1. The most significant reductions (-3 to -5 cm w.e. yr−1) are observed in the eastern and central Himalaya, based on estimates spanning from 2003 to 2020, a panel of researchers explained in the Journal ‘Nature Communications’.

Additionally, projections from the Coupled Model Intercomparison Project Phase 6 (CMIP6) by the end of the 21st century indicate a notable reduction in snow depth and a rise in temperature across the TP under all shared socioeconomic pathways (SSPs), the scholars said.

Snow and melting glaciers play crucial roles in the hydrology of TP and surrounding nations. “We used monthly mean precipitation data at a spatial resolution of 0.25° × 0.25° from GPCC for the period 1980-2020,” the researchers added.

The rising temperature trend and melting of snow and glaciers in TP therefore pose a significant threat to the regional climate, water security, and livelihoods of the people in South Asia. The analysis reveals significant spatial variability in snow depth, snowmelt, and snow water equivalent derived from the Global Land Data Assimilation System (GLDAS) in TP, the panel opined.

Worth mentioning, the Third Pole, also known as the Hindu Kush-Karakoram-Himalayan (HKKH) system, spreads over the western and southern edges of the Tibetan Plateau, covering a vast area of over 4.2 million square kilometers (1.6 million square miles) across nine countries. It borders ten nations, including Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal, Pakistan, and Tajikistan.

This region is dubbed the 'Third Pole' because its extensive glaciers and snowfields hold more frozen water than anywhere else on the planet except for the polar caps of the Arctic and Antarctic. Hosting the world’s highest peaks, including all 14 mountains towering over 8,000 meters (26,000 feet), it serves as the source of ten major rivers and plays a crucial role as a global ecological buffer.