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POSTED 23 FEB 2001 Ice in tropical regions is melting fast, according to research by geologist Lonnie Thompson, and the liquidation is accelerating. In 2000, Thompson found that the icecap on Kilimanjaro in East Africa has lost 82 percent of its area in 88 years.

A close-up of the icecap shows ice with some rock poking through. ABOVE: The icecap on Kilimanjaro, at the border of Kenya and Tanzania near the equator, seen in 1912.
Kilimanjaro photos courtesy Lonnie Thompson, Ohio State University

BELOW: Kilimanjaro's ice cap lost 82 percent of its area by 2000.
Brown mountain against a blue sky, streaks of white mark the ice caps on Kilimanjaro.

Just since 1989, one-third of the area has disappeared. Thompson, a professor of geology at Ohio State University, thinks the ice cap will be gone within a decade or two.

Kilimanjaro is at just 3 degrees south latitude, but it's so high --- the peak is 5,896 meters -- that snow can fall and gather into an icecap.

To freeze not
Thompson and his associates have found similar melting on glaciers in many parts of the globe. In Tibet, the largest plateau on Earth, measurements of oxygen isotopes indicate that the air has never been this warm -- at least since the glaciers formed. Temperatures are now increasing by 0.16 degrees Celsius per decade.

In the Peruvian Andes, glaciers are melting faster and faster as the years pass. From a series of photos, Thompson calculated that a glacier coming down from the Quelccaya ice cap is retreating by 155 meters per year. Between 1960 and 1978, the annual pace was less than five meters.

Glacier occupies the entire center of the picture; glacier flows down from icecap at the top of picture. ABOVE: The Qori Kalis glacier in Peru, shown in 1978.
Glacier photos courtesy Lonnie Thompson, Ohio State University.

BELOW:The Qori Kalis glacier in Peru in 2000.
A lake has formed in front of the glacier, and the glacier has retreated toward the back of the picture.

If the Peruvian glaciers melt away, the streams they supply will cease driving Peru's hydroelectric generators. That could force Peru to burn more fossil fuels for electricity, creating more carbon dioxide and then more global warming. That kind of vicious cycle could melt other ice in other places.

The melting of tropical glaciers may be due to one manifestation of global warming -- the warming ocean surface, which would loft more water vapor high into the atmosphere, carrying the latent heat that caused the evaporation. When the water vapor condenses into snow, that heat is released, melting high-altitude ice.

The ice melts
While proof of the relationship between carbon dioxide in the atmosphere and global warming remains elusive, the overall picture grows ever clearer -- and frightening.

Many climatologists say 1998 was the warmest year on record.

In the last century or so, Earth's lower atmosphere has warmed by half a degree Celsius.

After another century, the climate could be five degrees Celsius hotter. That blast-furnace pace of heating could be faster than any previous warm-up in the planet's history.

On Feb. 16, 2000, 3,000 climate scientists in the International Panel on Climate Change issued their strongest warning: "Projected climate changes during the 21st century have the potential to lead to future large-scale and possibly irreversible changes in Earth systems, resulting in impacts on continental and global scales."

map of world, with Kilimanjaro, Tibet, and Qori Kalis highlighted

Glaciers in these tropical locations are melting fast.

Overall, the future of tropical glaciers is highly liquid, Thompson told a meeting of the American Association for the Advancement of Science in February: "In the tropics, any glacier we have measurements on is retreating, and retreating faster than before."

-- David Tenenbaum







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