Know Climate Change

Science behind Climate Change


Changes in Cryosphere

Global warming is causing shrinkage in mountain glacier volume, decrease in snow cover, changes in the permafrost and frozen ground, reduction in the Arctic sea ice extent, coastal thinning of the Greenland ice sheet, and reduction in the seasonally frozen ground, river, and lake ice cover. These changes in ice cover contribute to an increase in sea levels.

The following graph depicts decadal variations in Northern Hemisphere snow cover for March-April.

Northern Hemisphere snow cover for March-April
Source: IPCC

You can view an animation depicting projected sea-ice extent at Hadley Centre

Ice sheets are known to respond to changes over very long time scales. Ice shelves lose mass by calving icebergs and melting at the base into the ocean. A warming of about 1 °C in the oceans can increase the melting of the base of an ice shelf at a rate of 10 m/year. These are, however, broad estimates, indicative of the reduction in the ice content. Records of previous ice ages indicate that ice sheets have shrunk in response to warming and increased in volume in response to cooling.

How does Cryosphere affect Climate?

The main components of the cryosphere are snow, river and lake ice, sea ice, glaciers, ice caps, and frozen ground. An important property of snow and ice cover is that it has high reflectivity, or the albedo effect. Nearly 90% of the solar radiation gets reflected by the cryosphere. Increase in temperature causes an increase in the melting of snow and ice cover, reducing their rate of reflectivity, thereby enhancing the absorption of radiation in the melted areas, thus resulting in increasing the warming rates.