Ice Dam to Break Prematurely on Argentine Glacier

[Sally Furniss]

A huge ice dam on Argentina's Perito Moreno glacier will break apart for the first time in the southern hemisphere winter, likely as a result of global warming, scientists and environmentalists said Monday.



The 60-meter (yard) high wall of ice holding back a portion of Lake Argentina breaks apart spectacularly in cycles of one year to several years, but always in summer, and is one of Patagonia's top tourist attractions.


"This is the first time the glacier breaks up in winter. It could be related to global warming as rising temperatures affects ice friction," said Los Glaciares National Park director Carlos Corvalan.


The Perito Moreno glacier, one of the world's largest, measuring 275 square kilometers (106 square miles) and five kilometers (three miles) wide at its mouth, is located 2,800 kilometers (1,740 miles) southeast of Buenos Aires.

A view of a natural tunnel formed in one of the sides of the Perito Moreno glacier in a process of an unexpected rupture during the southern hemisphere's winter months, near the city of El Calafate, in the Patagonian province of Santa Cruz, southern Argentina, July 7, 2008. [Photo: Agencie

http://english.cri.cn/2906/2008/07/08/1461s378193.htm

 

[Sally Furniss]

Re: Ice Dam to Break Prematurely on Argentine Glacier

The Perito Moreno Glacier (

50?29′S 73?03′WCoordinates:

50?29′S 73?03′W) is a glacier located in the Los Glaciares National Park in the south west of Santa Cruz province, Argentina. It is one of the most important tourist attractions in the Argentine Patagonia.
The 250 km? ice formation, of 30 km in length, is one of 48 glaciers fed by the Southern Patagonian Ice Field located in the Andes system shared with Chile. This icefield is the world's third largest reserve of fresh water.

Satellite image of the Glacier. Note the colour difference between both sides of the lake.


The Perito Moreno Glacier is one of only three Patagonian glaciers that are not retreating. Periodically the glacier advances over the L-shaped "Lago Argentino" ("Argentine Lake") forming a natural dam which separates the two halves of the lake when it reaches the opposite shore. With no escape route, the water-level on the Brazo Rico side of the lake can rise by up to 30 meters above the level of the main lake. The enormous pressure produced by this mass of waters finally breaks the ice barrier holding it back, in a spectacular rupture event. This dam/rupture cycle is not regular and it naturally recurs at any frequency between once a year to less than once a decade.

The glacier on the shore 2 weeks before the 2004 rupture


The terminus of the Perito Moreno Glacier is 5 km wide, with an average height of 60 meters above the surface of the water, with a total ice depth of 170 meters. It advances at a speed of up to 2 m per day (around 700 m per year), although it loses mass at approximately the same rate, meaning that aside from small variations, its terminus has not advanced or receded in the past 90 years. At its deepest part, the glacier has a depth of approximately 700 m.

Large piece of ice collapses as the glacier advances


The glacier first ruptured in 1917, taking with it an ancient forest of array?n (Luma apiculata) trees. The last rupture occurred in March 2006, and previously in 2004, 1988, 1984, 1980, 1977, 1975, 1972, 1970, 1966, 1963, 1960, 1956, 1953, 1952, 1947, 1940, 1934 and 1917. It ruptures, on average, about every four to five years, but the next rupture will be in march-april of 2008 (see the external links to see it live). http://en.wikipedia.org/wiki/Perito_Moreno_Glacier

 

[tropical]

Re: Ice Dam to Break Prematurely on Argentine Glacier

"... in a process of an unexpected ..."

of an very expected,

and at 2050 very finished process.