Glacier Disappearance Projected To Peak Mid-Century

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Context  

A study published in Nature Climate Change projects a sharp increase in the global loss of glaciers, with the peak disappearance rate—up to 4,000 glaciers per year—expected between 2014 and 2055, depending on the level of warming.

What is Glacier Retreat?

Glacier retreat (or glacial retreat) is the process where a glacier shrinks in size and its lower edge—the terminus—recedes upvalley. 

This happens when a glacier's "mass balance" is negative, meaning it loses more ice through melting, evaporation, or calving than it gains through new snowfall. 

Core Drivers of Accelerated Melt 

Global Warming & Greenhouse Gas Emissions: The burning of fossil fuels, industrial processes, and deforestation have increased atmospheric concentrations of carbon-di-oxide and methane. 

• These gases trap heat, raising global average temperatures and disrupting the seasonal balance between snow accumulation and melting.

Ocean Warming: Oceans absorb about 90% of Earth's excess heat, which rapidly melts and destabilizes marine-terminating glaciers and ice shelves.

Albedo Reduction:

• Black Carbon (Soot): Pollution from biomass burning and fossil fuels deposits soot on ice surfaces, which absorbs solar radiation instead of reflecting it.
• Feedback Loops: As white ice melts, it exposes darker land or water, which absorbs more heat and further accelerates the melting process.

Shifting Precipitation Patterns: Climate change is replacing snowfall with rainfall at high elevations. Less snow means glaciers lose more mass than they gain, resulting in a negative "mass balance."

Extreme Weather Events: Anomalous heatwaves—such as those recorded on the Tibetan Plateau in early spring 2022—can cause rapid, unexpected melt even at high altitudes traditionally expected to remain frozen. 

Region-Specific Factors 

• Himalayas ("Third Pole"): Rapid melting is exacerbated by local air pollution (black carbon) and infrastructure development in mountain regions.
• Greenland: Melting is strongly influenced by the "Jakobshavn Effect," where warm ocean currents at calving fronts cause inland instability.
• Antarctica: The "buttressing" effect of ice shelves is failing; as they thin due to warm deep-water circulation, land-based glaciers behind them flow faster into the sea.
• Mountain Glaciers (Alps, Andes): Smaller ice masses are highly susceptible to rising air temperatures and have neared or passed "peak water," causing a permanent decrease in meltwater runoff.

Impacts on Environment and Human Life

Threat to Water Security: Glaciers are natural 'Water Towers'.

• Approximately 1.9 billion people in Asia depend on meltwater from the Himalayan glaciers for drinking water, irrigation, and industry. (Source: World Bank, 2023)
• Initially, rapid melting causes increased river flows and flooding. However, as glaciers shrink past a 'peak water' point, river flows will drastically decline, leading to severe water scarcity downstream.

Increased Risk of Disasters:

• Melting glaciers lead to the formation of unstable Glacial Lakes, often dammed by loose moraine debris.
• A breach of these dams can cause catastrophic Glacial Lake Outburst Floods (GLOFs).
• Case Study (Sikkim GLOF, 2023): A GLOF from the South Lhonak Lake in Sikkim created devastating flash floods in the Teesta River basin. 
• It caused over 100 deaths and disappearances and washed away major infrastructure, including parts of the Teesta-III hydropower dam. This event highlights the growing GLOF threat in the Himalayas.

Sea-Level Rise: Glacier melt is a major contributor to rising sea levels, which threatens coastal communities, economies, and ecosystems worldwide.

Impact on Hydropower & Agriculture: Reduced and unpredictable river flows threaten hydropower generation and the agricultural sector, which are the lifelines for millions in downstream regions.

Hindu Kush Himalaya (HKH) 'Third Pole' Crisis

The HKH region is a climate change hotspot, warming at a rate faster than the global average.

• Future Projections: Under current emission scenarios, the region could lose up to 80% of its glacier volume by 2100. Even if the Paris Agreement goals (1.5°C) are met, a loss of 30-50% is projected. (Source: ICIMOD)
• Water Crisis Signal: The winter of 2023-24 saw snow persistence in the HKH region at its lowest level in 22 years, indicating a serious water crisis for river basins people. (Source: ICIMOD)

Source: DOWNTOEARTH