Colombia’s disappearing glaciers

Colombia has lost 50 percent of its glaciers in the last fifty years. Today, six glaciers remain nestled among the highest peaks of the three mountain ranges that traverse the country.

Scientists are scrambling to monitor and explain the rising atmospheric temperatures and changing weather patterns that have forced Colombia’s high-altitude glaciers into quick retreat.

“In the last six years there’s been total disequilibrium,” says Jorge Luis Ceballos, a research scientist at Colombia’s national institute of hydrology, meteorology and environmental studies (IDEAM). “If these conditions persist, it’s probable that they will disappear completely in the next 30 or 40 years.”

Ceballos and a team from the federally-funded IDEAM have installed five meteorological stations across Colombia’s highest peaks to monitor air temperatures, solar radiation and other factors that could be driving the retreat of the remaining glaciers.

Colombia’s glaciers are some of the few worldwide that are equatorial—Ecuador, east Africa and New Guinea host the others—which Ceballos says makes them particularly sensitive. “The high fragility of these zones make these ecosystems highly vulnerable to small climatic changes,” he says. Which is why he’s intent on monitoring atmospheric changes at these high-altitudes and mapping the area and volume of the remaining glaciers.

“But glacial melting is not as straightforward as people like to think,” says Stefan Hasenrath, a glaciologist and emeritus professor at the University of Wisconsin who has done fieldwork on equatorial glaciers in Ecuador, New Guinea and East Africa. He stresses that the notion that warming temperatures are the only reason for equatorial glaciers’ retreat at high altitudes is incorrect.

His research on cloud cover on Mount Kilimanjaro points to an important factor: solar radiation. Above a certain altitude, solar radiation is the driving factor of glacial retreat because warmer air simply contains more water vapor. At high altitudes this would fall as precipitation and presto, more glacial cover.

Another concept to appreciate is how melting happens at high altitudes. At air temperatures well below zero, Hasenrath points out, the only way melting can occur is through evaporation.

Though this takes a lot of energy, diminished cloud cover lets enough solar radiation through to drive this evaporation and glacial retreat, according to Hasenrath. At lower elevations, of course, temperatures can climb above zero and melting can occur traditionally.

One of the Colombian glaciers that Ceballos is continually hiking to altitudes of more than 15,000 feet to monitor is Ritacuba Negro in El Cocuy National Park, 250 miles northeast of Bogota. The alpine tundra—known as the paramo—is surrounded by snowy peaks and dotted with frailejones, squat thick-trunked shrubs named for their friar-like appearance.

The tundra at Ritacuba Negro used to host a large glacier. Ceballos’ evidence? A watercolor painting drawn in 1851 by the Italian geographer Agustin Codazzi. The glacier has since retreated to a point a five-hour hike away from the point denoted in the painting. IDEAM estimates this glacier’s retreat at 20-25 meters a year.

Fortunately for Colombians, most do not rely on glaciers for drinking water—save for a few villages near Cocuy—Ceballos points out, unlike regions lying near the Himalayas. Which may be keeping glaciers somewhat distant in their consciousness. “Glaciers are looked at in Colombia as something very remote, static and still,” sighs Ceballos.

“Glaciers are an alarm that has been going off for decades,” says Ceballos. “They tell us that in the high mountains of the Andes, strong and rapid changes are occurring.” And the disappearance of these glaciers could impact the paramo, the forests and other ecosystems, he says, although the extent of this impact is unknown without further monitoring.

The good news is, in an effort to fund more basic science, the Colombian government is financing Ceballos monthly trips to his country’s remaining glaciers.

Source | sciencefriday.com

Advertisements