20210531-世界银行-Glaciers_of_the_Himalayas_Climate_Change,Black_Carbon,and_Regional_Resilience_142页_13mb

Glaciers of the Himalayas: Climate Change, Black Carbon, and Regional Resilience

A Report Exploring Glacier Dynamics, Water Resources, and Policy Responses in the Himalaya–Karakoram–Hindu Kush Region

1. Introduction and Overview

This report examines the critical role of glaцiers in South Asia's water systems, focusing on how climate change and black carbon (BC) deposition are accelerating their melt. The Himalaya, Karakoram, and Hindu Kush (HKHK) mountain ranges contain nearly 55,000 glaciers, storing freshwater comparable to the world’s poles. These glaciers feed the Indus, Ganges, and Brahmaputra river basins, supporting millions of people through agriculture, hydropower, and water resources. The study highlights the combined impact of greenhouse gases and anthropogenic BC—generated from sources like diesel emissions, biomass burning, and brick kilns—on regional water availability and poses a threat to South Asia's development.

2. Glacier Melt Drivers

• Climate Change: Rising temperatures reduce glacier mass across the region, with warming trends strongest at higher elevations. By 2050, glaciers could lose 39–52% of their current mass under RCP 4.5 scenarios.
• Black Carbon: BC deposits reduce glacier albedo, increasing solar absorption and air temperatures. BC from regional emissions (e.g., residential combustion, brick kilns, and diesel vehicles) contributes to up to 50% of glacier melt acceleration. Policies to reduce BC could slash deposition by up to 73% (23% under current policies and 50% with additional measures).

3. Impacts on Water Resources

• Short-Term Gains, Long-Term Losses: Initial increases in glacial melt could offset water deficits, but sustained melting will exacerbate water scarcity. By mid-century, 700–800 million South Asians may face water stress.
• Hydrological Shifts: Changes in runoff timing disrupt agriculture, hydropower generation, and flood patterns. Glacial lake outburst floods (GLOFs) threaten downstream communities.
• Sectoral Effects: Water shortages impact energy (e.g., hydropower), tourism (degraded glacier-related attractions), and livelihoods of rural populations dependent on seasonal flows.

4. Solutions and Recommendations

• Policy Actions:
  • Accelerate BC reduction through cleaner cookstoves, vehicle emissions standards, and brick kiln upgrades.
  • Promote renewable energy and fuels to lower BC emissions.
• Water Management: Strengthen basin-based institutions and efficient water use to mitigate scarcity.
• Infrastructure: Develop storage projects to stabilize water availability amid changing flows.
• Regional Cooperation: Share data on BC emissions, flood risks, and best practices to address cross-border challenges.

5. Regional Cooperation

Climate change and BC pollution require collaborative strategies across South Asia’s HKHK region. By harmonizing policies and fostering knowledge exchange, countries can adapt to glacial retreat and safeguard shared water resources. Joint efforts to monitor BC and manage GLOFs are critical to ensuring regional resilience.

6. Conclusion

The report underscores that reducing BC alongside mitigating climate change is vital to protect South Asia's water towers. If unchecked, regional glacier loss could cripple economies and amplify social vulnerabilities millions of people. Achieving resilience demands rapid, unified action from policymakers, researchers, and communities.