Glaciers in retreat:

Andrew on May 31, 2015

Glaciers around the world are in retreat. Of the 250 alpine glaciers studied, the Taku Glacier in Alaska was the only glacier not retreating until, in 2019, it began retreating as well. At 1,500 metres thick, it’s one of the world’s thickest mountain glaciers, now retreating by up to 390 billion tons of snow and ice a year.

(This is a big deal. Mighty glacier finally succumbs to climate change: The Age: 8 Nov 2019)

The glacier altitude feedback cycle

This feedback occurs because the average temperature at the top of a mountain is lower than at sea level, and this is relevant because we have some thick ice sheets, for example:

  • up to 4,900 meters deep in Antarctica,
  • up to 3,000 metres in Greenland, &
  • up to 1,500 meters for mountain glaciers.
More glacial surface meltingA drop in the altitude of the glacier surface
*A rise in average temperature at the glacier surface

When the “glacier altitude feedback” is dominant: (1) more glacial surface melting causes (2) a drop in the altitude of the glacial surface, causing (3) higher temperatures at these lower glacial surfaces, which causes (4) more glacial surface melting, and (5) the cycle repeats.

This feedback cycle indirectly increases global temperatures as it (1) decreases the area of reflective glacial ice, and so (2) increases the absorption of the sun’s energy and (3) warms the planet.

The Extreme Ice Survey

The Extreme Ice Survey collects visual evidence of the impact of global warming on our planet, such as time-lapse photos of glacier contraction.  Outside of the Antarctic, 95% of the world’s glaciers are retreating. See:

  • the film “Chasing Ice”, produced in cooperation with National Geographic. It won an Emmy award as an outstanding nature program, or
  • the TED talk by James Balog in July 2009.

Related pages

Updated 28 March 2022