African ice under wraps

From:
http://www.nature.com/nsu/031117/031117-8.html

African ice under wraps
Secrets locked in Kilimanjaro's ice cap need urgent protection.
24 November 2003

BETSY MASON

The celebrated ice cap on Africa's loftiest peak could vanish within
20 years, taking with it a unique scientific resource. Now a
Zimbabwean scientist believes that the ice can be saved — by covering
it with a giant tarpaulin.

Tanzania's ice-crowned Mount Kilimanjaro is not only a top tourist
attraction and a national symbol. Its frozen cap, gradually deposited
over millennia, also records the history of East Africa's climate.

"If it goes, we'll lose some really precious information about the
climate of the recent past," says climatologist and Zimbabwe native,
Euan Nisbet of Royal Holloway University of London.

An expedition to Kilimanjaro in 2000 found just 2.2 square kilometres
of ice on the summit — 80% less than covered it in 1912.1 The peak
will be bare rock by 2020 if the ice continues to disappear at this
rate, says expedition leader Lonnie Thompson, a geologist at Ohio
State University in Columbus.

Thompson's team collected ice cores that preserve an archive of
African climate over the past 11,700 years — the only record of its
kind.

Although it's tempting to blame the ice loss on global warming,
researchers think that deforestation of the mountain's foothills is
the more likely culprit. Without the forests' humidity, previously
moisture-laden winds blew dry. No longer replenished with water, the
ice is evaporating in the strong equatorial sunshine.

Quick fix

Reforestation is the best long-term solution, but trees won't grow
fast enough to save the ice, argues Nisbet. A temporary band-aid is
needed. "The most obvious and simple solution would be to hang a white
drape over it to reflect sunlight and reduce wind," he says.

A white, synthetic drape hung over the 30-metre cliff-like edges of
the ice sheet, where most of the evaporation is occurring, might just
do the trick, Nisbet says.

But other scientists are sceptical. "This is probably not something
that would buy us much time," says Thompson. "My feeling is that the
glaciers will be lost no matter what we do. Nature is a huge force and
it's very hard to stop once it's in motion."

"It's feasible that we could bring about the glacier's demise even
more quickly," warns climatologist Doug Hardy of the University of
Massachusetts Amherst.

Although the tarpaulin would reflect most of Sun's energy away from
the ice, warmth would penetrate it and be trapped inside. The cover
could then act as a blanket, speeding up the melting.

With an estimated 50–100 tonnes of tarpaulin needed to cover the ice's
edges, not to mention the effort required to place it on the mountain,
the resources might be better spent on collecting more ice cores,
Hardy says.

But there is more at stake for impoverished Tanzania and Africa than
just a record of climate, says Nisbet. "The ice of Kilimanjaro is an
icon for all of Africa," he says. "Tanzania has tried very hard to
protect its natural assets, and it deserves a bit of help if something
can be done."

References

1. Thompson, L. G. et al. Kilimanjaro ice core records: evidence of
Holocene climate change in tropical Africa. Science, 298, 589 - 593,
(2002). |Link|