Ladakh’s giant ‘rivers of ice’ are slowing as the mountains warm, Pg2

Key Highlights:

• Glaciers in Ladakh's Zanskar region are slowing down, moving 2.4 meters per year slower per decade on average.
• A study published in The Cryosphere journal found this slowdown occurred between 1992 and 2023.
• The pace of surface thinning in these glaciers increased from 0.22 m/year (2000-2005) to 0.57 m/year (2015-2020).
• This phenomenon is attributed to climate change, causing glaciers to thin and reduce their flow.
• The slowdown has significant long-term implications for water security in the Indus basin.

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Detailed Insights:

• The Zanskar region glaciers are vital freshwater reservoirs, sustaining rivers, agriculture, and local communities in an arid environment.
• Glaciers receive most of their snowfall from mid-latitude westerly disturbances during winter.
• As glaciers thin, the driving stress decreases, which in turn slows down the ice transport from higher to lower elevations.
• This reduced ice transport means lower parts of the glacier receive less replenishment, accelerating shrinkage.
• The study highlights that glacier thinning is not just a consequence of warming but also alters the glacier's ability to move.
• While initial melting may temporarily increase runoff (peak water), long-term glacier water storage is declining.
• Similar glacier slowdowns have been reported globally in regions like the European Alps, Alaska, and the Tibetan plateau.
• The study emphasizes the need for more ground-based measurements to validate satellite data and improve glacier models.

Scientific/Technical Concepts Involved:

• Glacier Flow: The constant movement of ice from high accumulation zones to lower elevations due to gravity and internal deformation.
• Glacier Thinning: The reduction in a glacier's thickness, primarily due to increased melting and reduced ice accumulation.
• Driving Stress: The force exerted by the weight of the ice that causes a glacier to flow downhill.
• Peak Water: A hydrological phenomenon where meltwater runoff from glaciers initially increases due to warming, then declines significantly as glacier mass diminishes.