The dramatic ice retreat from 1950 to today

About 99% of all fresh water is found in the large polar and subpolar ice caps of Antarctica and Greenland: the situation is at the minimum

by Lorenzo Ciotti
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The dramatic ice retreat from 1950 to today
© Uriel Sinai / Stringer Getty Images

Despite their proximity and their importance to human populations, mid-latitude and tropical mountain and valley glaciers amount to only a small percentage of the ice on Earth.

About 99% of all fresh water is found in the large polar and subpolar ice caps of Antarctica and Greenland. These immense continuous continental-scale expanses of ice, 1.9 mi or more thick, cover much of the polar and subpolar Earth's mass. Similar to rivers flowing from a huge lake, numerous outlet glaciers transport ice from the edges of the ice fields to the ocean.

In the Arctic there has been a progressive retreat of the Arctic sea ice over the last 30 years as highlighted by satellite remote sensing data. In Greenland, regression of outlet glaciers has been observed, resulting from an increase in glacial flow velocity and destabilization of the mass balance of the ice shelf that was its source. The net volume loss and therefore marine contribution of the Greenland Inlandsis has doubled from 90 km3 to 220 km3 per year in recent years.

Iceland is home to Vatnajokull, the largest ice cap in Europe. The Breioamerkurjokull glacier is one of the outlet glaciers of Vatnajokull, and receded by approximately 1.2 mi between 1973 and 2004. At the beginning of the 20th century, the Breiðamerkurjökull extended 250 m (820 ft) into the ocean, but in 2004 its termini retreated 1.9 mi inland.

Greenland
Greenland© Gary M. Prior / Staff Getty Images
 

The Canadian Arctic Islands have a number of notable ice caps, including Penny and Barnes on Baffin Island, Bylot on Bylot Island, and Devon on Devon Island. All these ice caps have been slowly thinning and retreating. Those at Barnes and Penny on Baffin Island thinned annually from 1995 to 2000 by more than 3.3 ft at the lowest elevations.

The Antarctic climate is intensely cold and arid. Most of the freshwater reserve (in the form of ice) is contained in the large glacial expanses that cover the continent of Antarctica. The major examples of the drastic retreat of glaciers on the continent are the loss of large portions of the Larsen Shelf on the Antarctic Peninsula.

Ice shelves are not stable when melting occurs at the surface, and the collapse of the Larsen Ice Shelf was caused by warmer seasonal melt temperatures that caused the surface to melt, resulting in pools of shallow water forming above it. deep.

The Larsen platform lost 2500 km² of its area from 1995 to 2001. Over a 35-day period, starting on January 31, 2002, approximately 3250 km² of the platform area disintegrated. Its size is now 40% of its previous minimum stable extent.