Photo: Courtesy / Zac Robinson
Mountain glaciers, such as those of mount Saint Elias, in the Yukon, show the signs of the most early and the most dramatic loss of ice.
Climate change accelerates the melting of glaciers in British Columbia, the Yukon and Alberta, raising the threat of rising waters, and the formation of deserts, warn scientists.
The magnitude of the transformation of this area is spectacular, is David Hik, a professor of ecology at Simon Fraser University.
“Probably 80% of the mountain glaciers in Alberta and British Columbia will disappear in the next 50 years “, avance-t-il.
Of the glacier, and Peyto, which is located in the Rocky mountains and a part of the Banff national park, has lost nearly 70 % of its mass over the past five decades, illustrates Mr. Hik.
“It is a small glacier, but it is a typical case “, he says.
The mountains provide important insights into the future and can show us what we can expect.
— Zac Robinson, a professor at the University of Alberta
While the planet is warming at an increasing pace, the fragmentation of some of the ice caps will continue in the Rocky mountains, exposes Zac Robinson, who teaches at the University of Alberta.
Glaciers form when snow accumulates in the winter, not to be completely melted the next summer.
As the temperature climbs more quickly than expected, a rapid melting of the snow combined with lower rainfall results in a decline in glaciers, both in length and in volume, ” says Mr. Robinson.
According to the first Report on the state of the mountains, co-authored by MESSRS. Hik and Robinson, Canada has more covers glaciers than any other country, apart from the polar ice caps of Antarctica and Greenland.
Out of the approximately 200 000 square kilometres of hedges, more than a quarter is located in the west of the country, and the rest, in the arctic archipelago, according to the report published in may by the alpine Club of Canada.
Sensitive to climate change
Because of their sensitivity to warming, the mountain glaciers show signs of the earliest and most dramatic loss of ice. According to Mr. Robinson, the mount St. Elias, in the Yukon, are experiencing the most pronounced loss.
“The glaciers of the Yukon located in the chain of Saint-Élie have lost about a quarter of their ice cover since the 1950s “, he says.
Scientists have studied glaciers by a number of methods, including the analysis of old photographs and remote sensing.
According to the observations of Mr. Hik, the rate of melting of the ice vary from one place to another between 25 and 70 % “in the last six to seven decades” — rates similar to those recorded in the Alps and the Andes.
One of the first effects of the melting of the glaciers is an increase in the level of the sea, ” he says.
Over the past 50 years, the melting glaciers of the St. Elias range has already led to an increase in sea levels of 1.1 mm.
“It may not seem like much, but if you take the mount Saint Elias range, the Rocky mountains, the high mountains of the Arctic, the Himalayas-Hindu Kush, and the Andes and the Alps, and if you put all these contributions together, it counts for one of the largest increases in the sea level during the last decade. “
Arid and craters of dust
In addition to increasing water levels lead to coastal erosion and cause flooding, the melting also creates arid zones and craters of dust.
“In places like the river Kluane in the Yukon, there was much more dust, because the valley in which the river flows is almost dry, for an example there.
But the region continues to experience the katabatic winds — that is to say, that come from the glacier — and those are powerful enough to lift the dust from the beds of creeks.
This dust can harm vegetation by depositing on the trees and the plants and reducing photosynthesis, ” said Mr. Hik.
The melting also modifies the way the water flows and accumulates, creating lakes, wetlands, or even conditions similar to those of a desert.
These changes also affect the flora of the region. The tree line moves in height, while the willows and birch-trees thrive at elevations higher and higher.
Zac Robinson argues that it is important to study the mountains, since they act as sentinels, responding quickly and intensely to climate change.
“The mountains provide important insights into the future and can show us what we can expect. “