The existence of the Ruwenzoris, hidden for most of the year behind curtains of dense fog, was long debated by mapmakers and explorers of ancient Greece and Egypt.
Many doubted the legends about ice in the tropics, extending even to modern times.
In 1888 Thomas Heazel Parke, a medic marching across central Africa with the explorer Henry Morton Stanley, reported that he had looked up and "distinctly saw snow on the top of a huge mountain." Stanley dismissed Parke's account.
But a year later Stanley himself spied the glaciers through a parting of the clouds and quickly took credit as the first Westerner to confirm the ancient tales.
Those glaciers have since receded from an area of 1,600 acres (650 hectares) in 1906 to 870 acres (352 hectares) in 1955 to a mere 366 acres (148 hectares) in 2008, according to estimates by WWF, the Congolese Institute for Nature Conservation, and the Uganda Wildlife Authority.
"At this rate they will be gone in 30 years," WWF-expedition leader Languy said.
That would put in a crimp in tourist revenue to the region. More than 1,200 hardy tourists visited the glaciers last year, most coming from the Ugandan side of the border.
A Human Hand?
But why are the Ruwenzori glaciers shrinking?
According to a 2006 article in the journal Geophysical Research Letters, an increase in air temperature of about 1 degree Fahrenheit (0.5 degree Celsius) per decade is the culprit.
This finding implies the glaciers are dwindling due to human-caused climate change—the release of carbon dioxide and other greenhouse gases that are trapping heat near Earth's surface.
But other glacier experts, led by Thomas Mölg at the University of Innsbruck, Austria, say that a lack of accurate temperature readings make those findings unreliable. The mountains were inaccessible to researchers for much of the 1970s and 1980s due to civil strife in Congo and Uganda.
Molg suggests that a natural decrease in humidity, a trend that started in the late 1800s, is a greater factor in the steady erosion of the Ruwenzori glaciers.
"I wouldn't rule out that human activity is having an impact on the Ruwenzori," said Philip Mote, a research scientist at the University of Washington.
"But I would warn against the glib association that if something is changing it must be due to a human cause," said Mote, who co-authored a 2007 article in the magazine American Scientist asserting that, unlike disappearing glaciers in Europe and North America, the dwindling glaciers on Mount Kilimanjaro in Tanzania likely are not the result of global warming.
(Related: "Kilimanjaro's Glaciers May Last Longer Than Predicted" [May 1, 2007].)
Lonnie Thompson, an expert on Andean glaciers at Ohio State University, noted that, "throughout the tropics, all the glaciers are receding."
Whether the cause is decreased humidity or increased temperature, the results are the same, Thompson added.
"In the Andes precipitation has increased in the last hundred years," he said, "but the glaciers are still retreating."
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