AMHERST - If there is a poster child for global warming, it may be the vanishing snows of Kilimanjaro, which were predicted to disappear as early as 2015 in a widely-publicized report a decade ago.

However, the famed snowcap is stubbornly persisting on the African peak and may not fully vanish for another 50 years, according to a University of Massachusetts scientist who had a hand in the prediction.

The 2001 forecast was indirectly part of key evidence for global warming offered during the 2006 documentary “An Inconvenient Truth,” which warned of the threats of rising global temperatures. In it, former vice president Al Gore stated, “Within a decade, there will be no more snows of Kilimanjaro” due to warming temperatures.

"Unfortunately, we made the prediction. I wish we hadn't," says Douglas R. Hardy, a UMass geoscientist who was among 11 co-authors of the paper in the journal Science that sparked the pessimistic Kilimanjaro forecast. "None of us had much history working on that mountain, and we didn't understand a lot of the complicated processes on the peak like we do now."

“The glaciers are still shrinking, and in the next decades they will almost certainly disappear, but it will probably be on the order of three or four decades, maybe five,” Hardy said recently. “But we don’t know for sure. It might be in only two.”

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Mount Kilimanjaro, immortalized in Ernest Hemingway's 1936 short story, "The Snows of Kilimanjaro," sits on the plain of Tanzania, creating the highest point on the continent at 19,341 feet. An inactive tropical volcano, the mountain lies just 220 miles south of the equator. Yet, because of its great elevation, the temperatures on its peak are bitterly cold and glaciers flow down its slopes.

No one contests that the glaciers have retreated. Photographs show they have shrunk in area by more than 80 percent since 1912. In fact, glaciers from the Alps to the Andes have retreated dramatically since 1900.

However, in February 2001, at the annual meeting of the American Association for the Advancement of Science in San Francisco, Lonnie G. Thompson, a geoscientist from Ohio State University and the lead author of the paper that would appear in Science the following year, presented the preliminary findings of the researchers, who had extracted ice cores from Kilimanjaro's glaciers to assess their retreat.

The prediction, made amid growing alarm and controversy about global warming, garnered headlines around the world, largely because of the literary fame of the mountain.

Even though Thompson and Hardy warned at the time that their data was not complete enough to say exactly why the Kilimanjaro glaciers were retreating, the prediction galvanized those who believed drastic action needed to be taken to halt rising global temperatures.

“Science is and always has been a work in progress,” Thompson said. “As scientists, we publish the data based on our best understanding of that data at the time. That is the way science works.”

“When we went to Kilimanjaro to conduct this research in 2000, there had not been any studies conducted on those ice fields for 30 years,” he said.

Hardy says that since their initial visit to the mountain, the researchers have made periodic return trips to collect data. They found that although the glaciers cover less and less area, they are not losing thickness at the pace expected, and it is the thickness that will allow the glaciers to persevere for longer.

“Since 2000, we’ve lost about 30 percent of the ice area as of 2009, but the thickness of at least the main glacier, the northern ice field, hasn’t changed a great deal. It was 50 meters thick then and now it’s on the order of 45 meters thick,” he said.

Lack of long-term data concerning the thickness of the glaciers is what undermined their forecast, Hardy said. “Before 2000, we had no reference for how to treat the thinning other than by looking at historical photographs.”

H. Sterling Burnett, a senior fellow and head of environmental programs at the National Center for Policy Analysis, a conservative think tank based in Texas, said the Kilimanjaro prediction “is just one in a number of global warming scare stories that scientists have had to recant or at least modify in the face of substantial counter evidence.”

"Unfortunately, we made the prediction. I wish we hadn't."

- Douglas Hardy, UMass geoscientist

“The Kilimanjaro predictions were suspect at the time they were made. Critics noted that there was abundant evidence that the snow caps on Kilimanjaro had been in retreat decades before greenhouse gas emissions began to rise dramatically in the middle of the century,” he said.

“This doesn’t prove that humans aren’t contributing to global climate change, but it should call into question the confidence we can have in such claims,” Burnett said.

He worries that “costly, big government programs” to quell global warming will do more harm than good, “especially since the costs of these programs are felt now, and fall hardest upon the poor and those least able to absorb higher prices and lower employment in order to maybe stave off a small portion of distant-in-time harms.”

Representatives for Al Gore declined to comment on this article.

Thompson said that despite the recalibration of their prediction, the larger issue has to remain in sight.

“The real message here is that these ice fields will disappear. Whether it is in 10 years or 30 years is not the issue. The fact they will disappear within a few decades, as will many glaciers throughout the tropics, is the real concern,” he said.

“The opinions of global warming doubters will change on a dime depending on whether it is cold winter or a hot summer. The only opinion that matters is nature’s. Nature has a way of humbling us all. It still remains to be seen just who that will be” in the end, Thompson said.