BOULDER, Colo., May 31 (UPI) -- If Ernest Hemingway had written a short story called, let's say, "The Snows of Dinwoody Glacier," then the controversy about the retreating snows of Kilimanjaro might not be so resonant.
Thanks to Papa, however, equatorial Africa's landmark volcanic peak has become a focal point of the disappearing glaciers in the tropics. The northern ice field on the Tanzanian mountain may be gone in as little as 20 years -- even though it has survived for the last 11,000.
Is it another leading indicator of global warming? Or, are other factors at work that make it an anomaly?
"What you see in the tropics is a very uniform picture," Lonnie Thompson, distinguished professor in geological sciences at Ohio State University, told UPI's Climate. "Every glacier that we have any data on is retreating -- and some are accelerating."
It is not just the snows of Kilimanjaro that are disappearing, but also the snows of Quelccaya in Peru and of Glaciar Piedras Blancas in Patagonia, as well as the snows of Alaska, the Himalayas, Glacier National Park in Montana and nearly everywhere else around the world.
"Our best evidence for the current loss of tropical glaciers is mainly due to rising temperatures, and those temperatures are higher in many areas than they have been for more than 5,000 years, with the major increase occurring in the past 50 years," Thompson said. "Glaciers operate on thresholds and as such are extremely sensitive to global climate change."
Kilimanjaro symbolizes this not because its situation is remarkably different, but because of the importance of being immortalized by Hemingway. According to Thompson, the total area of ice on Kilimanjaro has declined from about 12 square kilometers (4.6 square miles) in 1910 to 2.5 square kilometers (about 1.0 square miles) in 2000. At that rate, all the ice will be gone by 2020. The northern ice field of the glacier has retreated 0.9 meters (about 3 feet) a year between 2000 and 2004.
The pattern is repeated around the globe. The terminus of Qori Kalis Glacier in Peru has retreated about 1,000 meters (3,281 feet) between 1960 and 2000.
Thompson has measured the terminus of Qori Kalis periodically since 1972.
"In the first period of measurement up to 1978, the terminus was retreating at 4.7 meters (15.4 feet) per year," he said. "When you come up to the most recent period of measurement, from 2000 to 2002, this terminus was retreating at 200 meters (131 feet) per year, or more than 40 times faster."
As with all things climate related, however, there are other possibilities at least for Kilimanjaro.
"A drastic drop in atmospheric moisture at the end of the 19th century and the ensuing drier climatic conditions are likely forcing glacier retreat on Kilimanjaro," according to a paper published earlier this year by the Royal Meteorological Society, written by Georg Kaser at the University of Innsbruck, Austria, and others.
Another hypothesis is land-use changes at the mountain's base have affected the glaciers.
Thompson acknowledged land-use patterns might be having some effect, but added the glacier almost certain is being whittled by global warming.
"We have from Kilimanjaro temperature and precipitation measurements made at the base of the mountain," he said. The data came from biologists studying baboons there who have measured daily maximum and minimum temperatures and precipitation since 1971.
"Precipitation has actually gone up slightly over that time period," Thompson said. "Temperatures have risen 3 degrees Celsius (5.4 degrees Fahrenheit). That has to be related to land use changes in the park -- either grazing or changes in forest cover, but there is no evidence that it is getting drier."
What is happening on Kilimanjaro is exactly what is happening on Mount Kenya and on other glaciated peaks around the world, he said. "You have to look at the balance of evidence. If Kilimanjaro was behaving somehow differently than those other sites, you could call it local effects."
The recession of tropical glaciers also is an important piece of evidence in a major temperature-measurement discrepancy. Remote sensing of the troposphere by satellites has not shown the same pace of warming as measurements of Earth's surface temperatures. This issue has been a major source of contention between the climate scientists who perceive severe warming and those who question the seriousness of the problem.
Climate models predict the troposphere and the surface will warm in tandem, but satellite measurements by a University of Alabama-Huntsville team have concluded they are not doing so. However, a re-analysis of the data by a University of Washington team -- led by atmospheric researcher Qiang Fu -- found a closer fit, but that work has not been accepted by the UAH team.
Many high-mountain glaciers are located in the zone of contention. Because temperatures in the tropics vary little from season to season, they can provide a stable record that can be used to verify one trend or another.
"Tropical glaciers give you a measurement of what's happening high up in the atmosphere," Raymond Pierrehumbert, a geology professor at the University of Chicago, told Climate.
Kilimanjaro, for instance, reaches 5,895 meters (19,340 feet). The Quelccaya ice cap in the Andes -- of which Qori Kalis is a part -- (reaches) 5,670 meters (18,898 feet).
"The receding glaciers are a lot easier to explain if you have increased warming with height," Pierrehumbert said. "If the models in the Fu version of the satellite data are right, that makes it a lot easier to explain the glaciers' receding."
About Kilimanjaro specifically, "a lot remains to understood," he said. "The others besides Kilimanjaro strongly support a more clear-cut case for the amplification of warming with height. The loss of glacial mass is a complex process. It is often not the result of melting, but of sublimation, where the ice is converted directly to vapor, but once melting starts to occur, it can be a runaway process. Once started, it takes 7.5 times less energy to melt ice than to sublimate it."
Thompson said his group placed a satellite-link weather station on Kilimanjaro in 2000 that measures hourly temperature changes.
"The big picture is that the temperatures on the summit are rising," he said. "That's a short time period, but it's the only measurement we've got. Last year, there were eight days that temperatures rose (to) over 0 degrees C (32 degrees F), where melting can take place."
"The people who use Kilimanjaro as an example to say there is no warming are misquoting the research," Pierrehumbert added.
So perhaps the snows of Kilimanjaro may next be for whom the bell tolls.
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Climate is a series examining the science behind and potential impact of global climate change, by veteran environmental reporter Dan Whipple. E-mail: [email protected]
