Global warming melts away as cause of glacial retreat

March 12, 2004

One of the icons of global warming - the retreat of Mount Kilimanjaro's glaciers - may not be due to rising temperatures after all.

A study has found the disappearance of ice from Africa's tallest peak is more likely to be the product of a decline in snowfall over the past 120 years rather than an increase in melting.

Furthermore, the scientists responsible for the research predict that the glaciers on the mountain's flanks could survive the century, though the rapidly shrinking icecap will probably be gone within 50 years.

The loss of Kilimanjaro's icefields, which are just 18 per cent of the size they were when first mapped in 1912, has been popularly portrayed as evidence of man-made global warming.

Environmental campaign organisation Greenpeace links the Tanzanian mountain's plight to the impact of increased greenhouse gas emissions on climate.

But the study, published in the International Journal of Climatology , has found no evidence of temperature rise in the region. Moreover, the summit plateau never gets above freezing.

The team, led by Georg Kaser, professor of tropical glaciology at the University of Innsbruck, Austria, and Douglas Hardy of Massachusetts University, US, has pinpointed a sharp drop in atmospheric moisture in the 1880s and a subsequent prolonged dry period in the region as being behind the decline.

The reduced amount of snow falling on and "topping up" the glaciers has been outstripped by the amount of ice that evaporates, leading to a net loss of mass.

Thomas Molg, a postdoctorate researcher in Professor Kaser's group, noted that while the summit glaciers were dead and would probably be gone within 50 years, those on Kilimanjaro's slopes were still moving and their retreat was likely to slow to a stop.

Dr Molg said that the fall in east African precipitation might be linked to variations in the surface temperature of the Indian Ocean.

"So there is a possibility that glacier retreat on Kilimanjaro is indirectly linked to some kind of global warming," he said.

David Collins, professor of physical geography at Salford University and director of the Alpine Glacier Project, said that the retreat of many of the world's ice fields was due to a combination of factors including lower precipitation, long-term climate trends, as well as rising temperatures.

"Times are generally hard for glaciers," Professor Collins said.


* More floods, droughts, heat waves and forest fires worldwide

* Collapse of Antarctic ice shelves

* Spread of tropical diseases such as malaria

* Sea level rises threaten low-lying countries

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