UPSC Mains 2017 GS1 Q8: How the Cryosphere Affects Global Climate

The cryosphere is all the frozen water on Earth: ice sheets, glaciers, sea ice, permafrost, and seasonal snow cover.

Ice and snow reflect 80-90% of incoming sunlight, a property called albedo. This keeps a large share of solar energy from being absorbed at all.

As ice melts, it exposes darker ocean or land that absorbs more heat. This drives further warming and further melting, a self-reinforcing cycle called the ice-albedo feedback loop.

Melting land ice, like glaciers and ice sheets, adds new water to the ocean and raises sea level. Melting sea ice, already floating, does not raise sea level directly.

Permafrost holds organic carbon built up over thousands of years. As it thaws, decomposition releases this carbon as methane and CO2, adding new greenhouse gases to the atmosphere.

Meltwater from the Greenland ice sheet adds freshwater to the North Atlantic. Enough freshwater could weaken the Atlantic Meridional Overturning Circulation, the current system that redistributes heat globally.

A weakened AMOC could paradoxically cool parts of Western Europe even as the global average temperature keeps rising, since the current normally carries warm water north along that coastline.

The Arctic is warming roughly two to four times faster than the global average, a phenomenon called Arctic amplification, driven largely by the region’s own ice-albedo feedback.

Mountain glaciers, like those across the Himalaya, feed major river systems downstream. Their retreat threatens long-term freshwater security for the large populations that depend on those rivers.

Define the cryosphere, then work through its climate effects: albedo feedback, sea-level contribution, permafrost carbon release, ocean-circulation disruption, and Arctic amplification, closing with its role in regional freshwater supply.