Washington, DC — Like canaries in coalmines, which once signaled the existence of life-threatening gases before human miners could perceive them, tropical glaciers are a warning for our civilization. That is the message of a growing body of research on climate change that has focused on melting glaciers and ice caps on mountains in Africa and South America.
Lonnie G. Thompson, a prize-winning researcher at Ohio State University, has been leading ice cap studies for two decades. His research offers a response to climate-change skeptics, who argue that the earth has experienced vast fluctuations in climate in the past and that there is no proof that human actions are responsible for the current increase in global temperatures.
In a paper presented at the 2001 annual meeting of the American Association for the Advancement of Science, Thompson revealed that some 82 percent of the massive ice field on Tanzania's fabled Mount Kilimanjaro has disappeared since it was first mapped in 1912.
This week, in the October 18 issue of the journal Science, Thompson and 10 colleagues have published the results of a study of six ice corps from Kilimanjaro, which document climate and environmental variability over nearly 12,000 years. The period of the greatest historically recorded drought in tropical Africa, some 4,000 years ago, was so severe that it has been considered instrumental in the collapse of a number of civilizations, including the Old Kingdom of Egypt. That drought was known to extend into the Middle East and western Asia, and Thompson's research in the Andes of northern Peru indicates that it may have been much more extensive.
Nevertheless, the findings of Thompson's team suggest that the current pace of climate change in eastern equatorial Africa is without precedent in its implications for human civilization. The melting of tropical glaciers is, according to Thompson, "an indicator of massive changes taking place and a response to the changes in climate." The evidence of the retreat and loss of these large bodies of ice are part of the evidence that has convinced him that global warming has begun to make an irreversible mark on the planet.
The ice of high-altitude glaciers is likely to be severely damaging to the areas above which they tower. "The loss of these frozen reservoirs threaten water resources for hydroelectric power production in the region, and for crop irrigation and municipal water supplies," Thompson says.
What the governments of those countries are doing, he says, "is cashing in on a bank account that was built over thousands of years but isn't being replenished. Once it's gone, it will be difficult to re-form." Loss of those water sources will likely result in a substantial increase in the use of fossil fuels, resulting in the addition to the atmosphere of the greenhouse gases that intensify global warming.
Other recently published research has documented a 40-percent shrinkage of the ice cap on Mount Kenya since 1963. In September the government of Kenya issued what the Nation newspaper in Nairobi called a "red alert", warning that streams from the mountain's slopes were drying up. The paper reported that Kenya's Central Provincial Water Engineer Tom Ogola revoked all water "abstraction" permits, warning of a severe shortage of water everywhere. "Most water is being consumed on the slopes by farmers," Ogola said. "Conflicts could occur if water does not reach the downstream communities."
Thompson sees the potential impact on local communities as broader than the crisis of water supplies. He points to African concerns that the loss of Kilimanjaro's ice cap will be devastating to the tourist trade that brings thousands of people to the region each year and fuels Tanzania's economy.
But he also sees the problem as an urgent challenge to scientists and policy makers globally to tackle the issue of global warming. "We need to take the first steps to reduce carbon dioxide emissions," he says. "We are currently doing nothing."