WHEN GIANTS FALL
The glaciers are a constituting part of the Patagonian North and South Ice Fields, whose combined territories comprise an area of 17.000 square kilometres.
At both sides of the Andean Ridge, a major number of glaciers are going through serious problems. The rate of the thinning and loss of mass from their surfaces has more than doubled during the decade of the nineties, therefore increasing the levels of water that melts into the sea. This is the resulting report of a thorough research performed by a scientist from the NASA along with his pairs from Chile, who analysed the data forwarded to them by this scientific agency of the United States of America.
In the last five decades, these reservoirs of potable water have experienced a strong and steady retreat of their front lines, along with a reduction of their ice surfaces. But in the lapse between the years of 1995 and 2000, the rates of thinning turned critical -particularly on glaciers like the Upsala in Santa Cruz- which resulted in a comparative rising of the sea levels of one tenth of a millimetre by year.
On the other hand, considering the period elapsed between the years of 1975 and 2000, the amount of decrease in the volumes of the ice fields of Patagonia had merely accomplished an equivalent augmenting of the sea levels of 0,04 millimetres.
The glaciers shared by Argentina and Chile had subsequently retreated in the period between 1995 and 2000 at a rate twice as fast as during the past 25 years, as concluded by the mentioned scholars.
The actual causes are related to the negative balance in the masses of the glaciers, as they gather a lesser amount of snow than the one they give up by the process of melting or by the crumbling of the ice fields which are produced by the raising of the global temperature levels and the diminishing of the amounts of precipitation in the Southern territories of Chile and Argentina.
To use a realistic example, the areas located to the South of the City of Comodoro Rivadavia presented a rise in its average temperatures which ranged from 0,4 to 1,4 centigrade degrees at both sides of the Andes, showing a pattern that seems to increase towards the South.
Whereas the temperature rates on the higher grounds (More than 1300 m.a.s.l.) also presented a rising of temperatures of about 0,5 centigrade degrees during the last 25 years, this actually implied a smaller amount of falling snow to feed the glaciers, which as a result suffered a increase in their normal production of crumbling ice heaps and the subsequent loss of mass.
But the researchers bear little doubts concerning the side effects of what constitutes a world wide problem: the rising of the average temperatures of the planet.
"In order to stop the increasing rate of the thinning of the glaciers, the only possible action left is to reduce the emission of the hothouse gasses, as has been conclusively forewarned by the Tokyo Protocol" assure the researchers Casassa and Rivera. But the question that remains to be answered is how much of this global heating is due to natural and unavoidable causes.
Furthermore, they sustain that "the main cause for the recession of the glaciers of the Patagonia has to be the resulting negative balance off achieved mass, due to the recent changes in the climate". The glaciers of the Patagonia embrace an area which is smaller than those of Alaska (90 thousand square kilometres), nevertheless being responsible for almost 90 per cent of the global amount of the sea level increase occasioned by mountain glaciers, compared with a mere 30 per cent accounted by those of Alaska.
According to the researches carried out at the Chilean Investigation Centre, only a few glaciers have presented no receding changes on their fronts, and only three had managed to show an advance: the Perito Moreno, the Trinidad and the Pïo XI. Besides the tendency to retreat showed by the fronts of the glaciers, these researchers documented a serious loss of ice surfaces which they calculated of around 500 square kilometres between the years of 1945 and 1968.
Meanwhile, a group of scientists from the Research Centre of Conicet-Argentina, had also called attention over the El Martial Glacier, one of the main tourist attractions of Ushuaia.
According to the study completed by Jorge Strelin and Rodolfo Iturraspe, this glacier had lost some 70 hectares of ice during the last 100 years.
Between the years of 1898 and 1970, the Martial Glacier reduced its area by 26 hectares compared to its original extension. This retreat became more rapid during the period between 1970 and 2000, during which the area shrunk by 44 hectares. These numbers attain more relevance if we notice that the present extension of the glacier is only 23 hectares.
This thinning of the ice of the glaciers, as in the Upsala in Santa Cruz or the Martial, is most probably going to bring serious troubles to every nearby ecosystem.
"The sweet water volumes that presently melt and drift into the sea (Causing the rising of its levels), turn salty, that is, they cease being potable. If the mass of ice that is lost is superior to the one that is renewed by snow fall, then the resulting balance of the glaciers in the region becomes negative", asserts Jorge Strelin.
The scientist is of the opinion that the impact of the deterioration of the Patagonian Ice Fields could bring a "strong aridity in the zones next to the glaciers, with the subsequent disappearance of the existing animal and plant species".
For a period of 41 years, the great majority of the glaciers have experienced a retreat, while only a few are still unharmed and two others show a slow progress. The impressive Perito Moreno Glacier, frequently oscillating with a net income of 4,1 square kilometres over 39 years has actually shown no variations. The Pío XI Glacier in Chile, the biggest of South America, engrossed its area by 1,45 square kilometres (288m) during the same period of time. The most dramatic loss occurred in the O'Higgins Glacier, diminishing by 1,21 square kilometres, being by far the largest deficit in all of Patagonia.
The information used to make this document was obtained from:
Eric Rignot of the NASA.
Andrés Rivera, researcher from the Universidad de Chile.
Gino Casassa, researcher from the Centro de Estudios Científicos in Valdivia, Chile.
Jet Propulsion Lab from the Technological Institute of California, USA.
Pedro Skvarca and Hernas de Angelis, researchers from the Instituto Antártico Argentino.