Snows Of Kilimanjaro Shrinking Rapidly, And Likely To Be Lost


This is one of a growing number of isolated remnants of ice spires  
that were once full glaciers in the crater of Mount Kilimanjaro in  
Africa. (Credit: Photo by Lonnie Thompson, Ohio State University)
ScienceDaily (Nov. 3, 2009) — The remaining ice fields atop famed  
Mount Kilimanjaro in Tanzania could be gone within two decades and  
perhaps even sooner, based on the latest survey of the ice fields  
remaining on the mountain.

The findings indicate a major cause of this ice loss is very likely to  
be the rise in global temperatures. Although changes in cloudiness and  
precipitation may also play a role, they appear less important,  
particularly in recent decades.

The first calculation of ice volume loss indicates that from 2000 to  
2007, the loss by thinning is now roughly equal to that by shrinking.

These predictions, published in the journal Proceedings of the  
National Academy of Sciences, are among the latest dramatic physical  
evidence of global climate change.

Paleoclimatologist Lonnie Thompson, professor of earth sciences at  
Ohio State University, and his colleagues amassed a trail of data  
showing the rapid loss of ice atop Africa's highest mountain:

•  85 percent of the ice that covered the mountain in 1912 had been  
lost by 2007, and 26 percent of the ice there in 2000 is now gone;

•  A radioactive signal marking the 1951-52 "Ivy" atomic tests that  
was detected in 2000 1.6 meters (5.25 feet) below the surface of the  
Kilimanjaro ice is now lost, with an estimated 2.5 meters (8.2 feet)  
missing from the top of the current ice fields;

•  The presence of elongated bubbles trapped in the frozen ice at the  
top of one of the cores shows that surface ice has melted and  
refrozen. There is no evidence of sustained melting anywhere in the  
rest of the core that dates back 11,700 years;

•  Even 4,200 years ago, a drought in that part of Africa that lasted  
about 300 years and left a thick (about 1-inch) dust layer, was not  
accompanied by any evidence of melting. These observations confirm  
that the current climate conditions over Mount Kilimanjaro are unique  
over the last 11 millennia.

"This is the first time researchers have calculated the volume of ice  
lost from the mountain's ice fields," said Thompson, a research  
scientist with Ohio State's Byrd Polar Research Center. "If you look  
at the percentage of volume lost since 2000 versus the percentage of  
area lost as the ice fields shrink, the numbers are very close."

While the loss of mountain glaciers is most apparent from the retreat  
of their margins, Thompson said an equally troubling effect is the  
thinning of the ice fields from the surface.

The summits of both the Northern and Southern Ice Fields atop  
Kilimanjaro have thinned by 1.9 meters (6.2 feet) and 5.1 meters (16.7  
feet) respectively. The smaller Furtwangler Glacier, which was melting  
and water-saturated in 2000 when it was drilled, has thinned as much  
as 50 percent between 2000 and 2009.

"It has lost half of its thickness," Thompson explained. "In the  
future, there will be a year when Furtwängler is present and by the  
next year, it will have disappeared . The whole thing will be gone!"

Thompson's team drilled six cores through Kilimanjaro's ice fields in  
2000 and published their findings in the journal Science two years  
later. That work established a detailed baseline against which more  
recent data can be compared.

Thompson said the changes occurring on Mount Kilimanjaro mirror those  
on Mount Kenya and the Rwenzori Mountains in Africa, as well as  
tropical glaciers high in the South American Andes and in the Himalayas.

"The fact that so many glaciers throughout the tropics and subtropics  
are showing similar responses suggests an underlying common cause. The  
increase of Earth's near surface temperatures, coupled with even  
greater increases in the mid- to upper-tropical troposphere, as  
documented in recent decades, would at least partially explain the  
observed widespread similarity in glacier behavior," he said.

Along with Thompson, Ellen Mosley-Thompson, Henry Brecher and Bryan  
Mark, all with the Byrd Polar Research Center, and Douglas Hardy from  
the University of Massachusetts all contributed to the study.

The research was sponsored primarily by the Paleoclimate Program of  
the National Science Foundation with additional support from the  
Climate, Water and Carbon (CWC) Program at Ohio State University.

Adapted from materials provided by Ohio State University. Original  
article written by Earle Holland.

s. e. anderson is author of "The Black Holocaust for Beginners"
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