Global Warming and Lake Ice
23 FEB 2001
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.
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
The icecap on Kilimanjaro, at the border of Kenya and Tanzania near
the equator, seen in 1912.
Kilimanjaro photos courtesy Lonnie Thompson, Ohio
Kilimanjaro's ice cap lost 82 percent of its area by 2000.
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.
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.
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 Qori Kalis glacier in Peru, shown in 1978.
photos courtesy Lonnie Thompson, Ohio
Qori Kalis glacier in Peru in 2000.
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.
While proof of the relationship between carbon dioxide in the atmosphere
and global warming remains elusive, the overall picture grows ever clearer
-- and frightening.
climatologists say 1998 was the warmest year on record.
the last century or so, Earth's lower atmosphere has warmed by half
a degree Celsius.
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.
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."
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