COLUMBUS, Ohio -- A team of Ohio State University researchers is warning that some of the most compelling evidence yet for recent global warming may be found in the tropics and subtropics, rather than in the polar regions where early signs of warming are anticipated.
Ice caps in alpine regions throughout the tropics and subtropics are melting at a phenomenal rate, while, last year, other scientists discovered that the freezing point in the upper atmosphere has been gaining altitude. These findings may be among the best evidence to date that the planet is experiencing a recent and rapid warming.
Ellen Mosley-Thompson, a professor of geography at Ohio State, told researchers attending the annual meeting of the Association of American Geographers in Fort Worth on April 3 that the climatic and environmental changes will have massive impacts on human populations around the globe.
Consider the evidence:
· The edge of the Qori Kalis glacier that flows off the Quelccaya ice cap high in the Peruvian Andes Mountains was retreating at a rate of four meters (13 feet) annually between 1963 and 1978. By 1995, that rate had grown to 30 meters (99 feet) each year.
· The freezing level in the Earths atmosphere -- the height where the air temperature reaches 0 degrees C -- has been gaining altitude since 1970 at a rate of 4.5 meters (nearly 15 feet) each year.
· Ice cores taken from the Dunde ice cap in eastern Tibet have shown that the last 50 years were the warmest in recorded history. A similar ice core record from the Huascaran ice cap in Peru has shown a strong warming over the last 200 years.
"Most of the evidence for warming that we see in these high alpine ice caps is in regions that are already water stressed," Mosley-Thompson said. "These tropical areas are where most of the planets population lives and where subsistence agriculture is incapable of feeding the population. And in the future, the greatest increase in population will occur here."
For years, scientists have argued whether the evidence for changes in world climate were being hidden behind normal climate variations. The Ohio State team now believes that the evidence is getting stronger at the same time our ability to decipher it has improved dramatically.
They cited the loss of ice volume in the tropical and subtropical ice caps, in the Antarctic Peninsula, and in the Russian Arctic, along with increased snowfall over East Antarctica, as further evidence of change.
Mosley-Thompson said that in spite of this evidence, little will probably be done to address the probable underlying causes of these changes until the people who make environmental policy decisions recognize the immediacy of the problem.
"Were making massive changes to the climate on an unprecedented scale in some parts of the globe," she said. "This kind of discussion has to find its way into the general conversation."
Mosley-Thompsons co-author on the paper was Lonnie Thompson, professor of geological sciences at Ohio State. Both are researchers with the Byrd Polar Research Center at the university.