December 8, 2011

Gunn Glacier Retreat, lake expansion, New Zealand

Posted by Mauri Pelto

Gunn Glacier is a small cirque glacier that lies beneath Mount Gunn. A lake has formed recently and is continuing to expand. The 2000 based map of the area published in , does not show a lake, but does at the terminus indicate a small water body surrounded by snow.  By 2015 the lake is shown in New Zealand Topo replacing much of the glacier area.


Topographic Map from 2000

moutn gunn map update

Current Topo map.

The New Zealand NIWA has monitored the snowline of New Zealand glaciers over the last 15 years and monitored the volume and area loss of these glaciers including Tasman and Donne Glacier, other like Murchison Glacier are also retreating. On Gunn Glacier the key factor is that four of the last 11 years NIWA has observed that the glacier has lost nearly all of its snowcover indicating a glacier without a persistent accumulation zone, (Pelto, 2010). The glacier area has been reduced by 40% from its 1972 mapped area. The 2006 imagery in Google Earth indicates a number of new icebergs adrift in the lake. The lake is now 300 meters across. A view of the cirque indicates a number of bare rock patches on upper sections of the glacier (bottom image), indicating a lack of a consistent accumulation zone. This glacier is thin and without a consistent accumulation it cannot survive (Pelto, 2010). TBy 2012 the glacier has retreated significantly losing more than 25% of its total area. The continued expansion of rock areas amidst the glacier and of the lake will lead to the loss of this glacier in the next two decades with a continuation of current climate.

gunn glacier 2006

Gunn Glacier in 2006 Google Earth image.  Red arrows the 2006 terminus position yellow arrows 2012. 

gunn glacier 2012

Gunn Glacier in 2012 Google Earth image.  Red arrows the 2006 terminus position yellow arrows 2012.