THE ASTUTE BLOGGERS

"Reuters": A photo of Mount Kilimanjaro stripped of its snowcap for the first time in 11,000 years will be used as dramatic testimony for action against global warming as ministers from the world's biggest polluters meet today. Gathering in London on Tuesday for a two-day brainstorming session on the environment agenda of Britain's presidency of the Group of Eight rich nations, the environment and energy ministers from 20 countries will be handed a book containing the stark image of Africa's tallest mountain, among others.

"This is a wake-up call and an unequivocal message that a low-carbon global economy is necessary, achievable and affordable," said Steve Howard of the Climate Group charity which organised the book and an associated exhibition. "We are breaking climate change out of the environment box. This crisis affects all of us. This is a global challenge and we need real leadership to address these major problems -- and these ministers can give that leadership," he told Reuters.

The pictures include one of Kilimanjaro almost bare of its icecap because of global warming, and coastal defences in the Marshall Islands threatened with swamping from rising sea levels.

... reports of glacial recession on Kilimanjaro first emerged in 2002, the story was quickly picked up and trumpeted as another example of humans destroying nature. It's easy to see why: Ice fields in the tropics—Kilimanjaro lies about 220 miles (350 kilometers) south of the Equator—are particularly susceptible to climate change, and even the slightest temperature fluctuation can have devastating effects.

"There's a tendency for people to take this temperature increase and draw quick conclusions, which is a mistake," said Douglas R. Hardy, a climatologist at the University of Massachusetts in Amherst, who monitored Kilimanjaro's glaciers from mountaintop weather stations since 2000. "The real explanations are much more complex. Global warming plays a part, but a variety of factors are really involved."

According to Hardy, forest reduction in the areas surrounding Kilimanjaro, and not global warming, might be the strongest human influence on glacial recession.

"Clearing for agriculture and forest fires—often caused by honey collectors trying to smoke bees out of their hives—have greatly reduced the surrounding forests," he says. The loss of foliage causes less moisture to be pumped into the atmosphere, leading to reduced cloud cover and precipitation and increased solar radiation and glacial evaporation.

Evidence of glacial recession on Kilimanjaro is often dated from 1912, but most scientists believe tropical glaciers began receding as early as the 1850s.

Stefan L. Hastenrath, a professor of atmospheric studies at the University of Wisconsin, Madison, has found clues in local reports of a dramatic drop in East African lake levels after 1880. Lake evaporation indicates a decrease in precipitation and cloudiness around Kilimanjaro.

"Less cloud coverage lets more sunlight filter through and hit the glaciers," Hastenrath said. "That increase in sunlight then provides more energy for evaporation of the glacier."

Hastenrath found further evidence in sailing expedition reports from the same period. "Ships along the East African coast recorded very fast equatorial winds around 1880," he said. "Just like today, swift westerlies are always linked with drier seasons in East Africa, so it's very likely Kilimanjaro had a dry period around this time."

Along with a higher risk of evaporation, a drop in precipitation also makes for a dark glacial surface, made up of old, dirty snow. A darker glacial surface absorbs more solar radiation than fresh, white snow (like a blacktop playground baking in the sun).

Global warming began to take effect in East Africa by the early 20th century.

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