Ecuadorean and French scientists take samples from the Antisana glacier. In the background, to the left, rises Cotopaxi, one of the world's highest active volcanoes.
Credit: Courtesy of Bernard Francou/IRD
As Humans Advance, Andean Glaciers Recede
By Gonzalo Ortiz
The huge reserves of freshwater frozen in the Andes Mountains have been rapidly diminishing since the mid-20th century due to the "flawed model of energy consumption," says at least one scientist.
QUITO, Jun 7 (Tierramérica).- The spectacular glacier number 15 of Altisana, one of the Ecuadorean capitals' sources of potable water, lost at least 36 percent of its original mass in the last 50 years.
The Antisana is a snow-capped peak of the eastern branch of the Andes range, whose three humps can be seen from Quito on clear days. It is located at the same latitude as the capital, 50 kilometers to the east.
Because of its strategic importance, it is the most studied of these Andean peaks. The glacier's length is measured each year and its mass each month, as part of tracking efforts by France's Institute of Research for Development (IRD) and Ecuador's National Meteorology and Hydrology Institute (INAMHI) and Quito's Metropolitan Sewage and Potable Water Agency (EMAAP-Q).
Cotopaxi, one of the world's highest active volcanoes, whose snow-covered cone can also be seen from Quito, lost 40 percent of its glacial mass between 1976 and 2006, said Bernard Francou, IRD representative in Ecuador, in a Tierramérica interview.
The studies by IRD and its local counterparts have shown that the same thing is happening to Ecuador's glaciers as to those of the Real branch of the Andes, in Bolivia, and the Blanca range, in Peru and Colombia. They have lost 30 percent of their mass, on average.
In the case of glacier fields below 5,400 meters above sea level, the deterioration is greater, as is the case of Chacaltaya and Charquini in Bolivia, Broggi, Yanamarey and Pastoruri in Peru, and Carihuairazo in Ecuador, which are predicted to disappear altogether within 10 to 20 years.
Bolívar Cáceres, head of the Ecuador glacier project that INAMHI has been operating since 2000, told Tierramérica that they are "monitoring the balance of mass, energy and dynamic of the glaciers, two on Antisana (Los Crespos and No. 15) and on Carihuairazo."
Cáceres believes there has to be a more detailed study of the changes associated with climate variations "and its possible relation to global warming, which is not yet well understood."
Environmental engineer Margarita Arias, who is writing her master's thesis on the Antisana glacier, told Tierramérica she is using mathematical models to determine which of the meteorological variables -- temperature, wind speeds, sunshine, etc. -- has the greatest effect in causing the glacier to shrink.
Although we know it is related to climate change, "what we are trying to determine is its influence in an exact way," Cáceres said.
After many studies, Francou's conclusion, with the usual caveats that scientists make, is that "the increase in the atmospheric temperature, and its effect on the altitude of the snow/rain limit, is the most likely cause of the glaciers' higher line of equilibrium."
The shrinking of the glaciers is one of the markers of climate change, said Francou, a leading international expert on the issue and author of many widely read scientific books and articles.
Things have changed radically throughout the tropical Andes in the last 35 years, even if the ice masses have been shrinking since the end of the "Little Ice Age," he said.
Paleoclimatologists have thus dubbed the cold period that began in the 14th century and ended in the mid-19th century, and in the case of the equatorial Andes in particular, ending around 1880.
"The dramatic loss of glaciers in recent decades is produced by human activities, the consequence of the flawed model of energy consumption that today's civilization clings to," said Francou, who collaborated on the reports of the Intergovernmental Panel on Climate Change (IPCC).
Francou and his colleagues are conducting research using a variety of methods, including "ice archives," which are ice core samples to test for chemical and isotopic markers.
IRD and Andean scientists have taken deep samples from Ecuador's Chimborazo (6,280 meters above sea level), the Illimani (6,360 meters) and the Sajama (6,550 meters) in Bolivia, and shallower perforations in the Ecuadorean glaciers Antisana, Cotopaxi and Cayambe.
Studying the ice core samples from deep within the glaciers, the scientists have been able to reconstruct the climate of the last 20,000 years to design climate models for the present and future.
To understand the history of the glaciers in the recent centuries, in addition to these "ice archives," additional sources are utilized, such as old maps and observations recorded since the 18th century by scientists, explorers and even painters -- although these are seen with a critical eye.
Glaciologists today base their measurements on the deposits that the glaciers leave and on precise mapping of the changes in the surface, using aerial photographs.
Combining these methods, they found that the permanent snow line of the equatorial Andes remained constant at altitudes of 4,750 to 4,800 meters from the early 18th century to the early 20th century, then gradually receded so that by 1975 it was located between 4,900 and 4.950 meters above sea level.
Since then, glacier loss has accelerated sharply. Today the permanent snow line is at 5,100 meters. The few glaciers that have survived below that altitude on some mountains in Ecuador are condemned to disappear within the next decades, according to the scientists.
But Francou resists speculating about what will happen to the larger glaciers, which are generally located higher than 5,100 meters.
"To know that would require relating mathematical models on the climate trends of the future with a model of its dynamic response. That would require a base of glaciological information that does not yet exist about any of the Andes mountains," he explained.
"As such, any sort of speculation or peremptory declaration that ends up in the press about the disappearance of the glaciers within such-and-such period has no scientific basis," said the expert.
Nevertheless, he accepts that the simple extrapolation of climate trends of the last 35 years into the next few decades indicates that "it is fatal for many glaciers, especially the smaller ones, which are the most imbalanced in relation to the current climate."
"But the climate is our responsibility!" he exclaimed. "We have to do everything we can to reverse this trend... Each person, from where they can. That is why the press is so important."
* IPS correspondent.