Kilimanjaro is on the Verge of Losing its Multi-Climate Appeal

In 2002, Lonnie Thompson and his colleagues from Ohio State University shocked the scientific community with their prediction that the ice fields capping the Kilimanjaro Mountain would disappear between 2015 and 2020. Returning to the mountain last week, researchers have sadly found that their prediction is coming true even faster than expected.

For Thompson, a professor of geological sciences, this third expedition was all too much like visiting a sick friend in failing health. "The change there is so dramatic," he said. "We can see it both in the field and from aerial photographs of the mountaintop. I would say it is on track to disappear, and the rate of ice loss may even be accelerating."

In order to compute how fast the ice is disappearing scientists have to compare past data records with current records. Such studies found that between 1912, when the mountain was mapped for the first time, and 2000 about 82 percent of the glacial ice had melted.

Thompson team made its shock 2002 assessment by comparing aerial photos from the year 2000 with those from 1962. This showed that the tops of the ice fields had lowered by at least 17 meters since 1962 - an average reduction in height of about a half-meter each year.

Photo credit: Lonnie Thompson, Ohio State University

This expedition didn't bring any good news for Tanzania. "There has been no accumulation of new ice forming on any of those ice fields since 2000," he said. "With the new aerial photographs, we will be able to calculate for the first time, not only the area of ice loss, but also the volume of water lost, since the last photos were taken in 2000."

The impact of the melting of Kilimanjaro in Tanzania is now being assessed. The ice fields so near the equator are a major tourist attraction but the potential decrease in tourism might be only a minor problem compared to the problem of water supply.

The water the population living around the base of the mountain uses for drinking and irrigation comes from two sources: the melting water flowing from the glaciers, and precipitation in the rainforests.

"What isn't clear", Thompson said, "is the proportion of the water that comes from each source and the age of the spring and well water currently being consumed. If most comes from the rainforests, then the impact is lessened, but if glaciers provide the larger portion, the loss of the ice fields could be catastrophic."

In order to discover the relative importance of each source of water the scientists will test the water for tritium, a rare radioactive isotope of hydrogen detectable in the water. Above-ground tests of nuclear weapons in the 1950s and 1960s dramatically increased the normal levels of tritium in water.

"If the water samples have high levels of tritium, it means that more of the spring water is younger and likely comes from the rain forest," he said. "But if the water is low in tritium, it means that the water is older, and that more of it originated from Kilimanjaro's ice fields. And if the ice fields vanish, so might a large portion of the source of spring water."

In addition, the scientists will also conduct chemical tests of the water from glaciers and will also use radiocarbon dating.

"What will happen to the water supply for these people when the glaciers disappear?" Thompson asked, "And disappear they surely will."


Photo credit: NASA World Wind.