The Heat Is Online

Melting of Earth's Glaciers Accelerates

The vast majority of the earth’s glaciers have been melting for at least two decades. The most recent measurements indicate that the so-called rate of "glacial retreat" is accelerating rapidly. "Between one-third and one-half of existing mountain glacier mass could disappear over the next hundred years," the IPCC declared in 1995,

One indication is that the volume of the world’s 500,000 small glaciers, such as those found in the Alps, has shrunk markedly in the last century -- and some scientists suspect that water from the melting mountain ice has raised sea levels by nearly half an inch since 1960. Glaciologist Mark Meier, of the University of Colorado, noted that small glaciers have lost more than 10 percent of their total mass in this century -- while Alpine glaciers have lost almost 50 percent of their ice due to rising global temperatures. Presenting his findings at a 1995 conference of the International Union of Geodesy and Geophysics, Meier theorized that water loss from small glaciers has accounted for a significant portion of the observed sea level rise over the last twenty years.

Halfway around the world, Australian researchers discovered recently that glaciers in Indonesia have receded at a rate of 45 meters a year over the past twenty years. Comparing current measurements to photos and maps from the 1930s, researchers James Peterson of Monash University in Melbourne and Geoffrey Hope of the Australian National University calculated that the rate at which the mid-latitude glaciers are retreating have accelerated from 30 to 45 meters a year between 1971 and 1993, according to an article in a June, 1995, issue of New Scientist.

Nor is the glacial retreat confined to warmer regions. Strong indications of warming have been found in ice core drilling in glaciers on the Tibetan Plateau, which indicate that the last fifty years appear to be the warmest in the last 12,000 years. That assessment comes from two of the world’s leading glaciologists, Drs. Lonnie G. Thompson and Ellen Mosley-Thompson at Ohio State University. The greatest rate of retreat they discovered is occurring in the largest glacier in the Peruvian Andes. The speed with which it retreated between 1963 and 1983 has tripled between 1983 and 1991 with a seven-fold increase in the rate of loss of its volume of ice. Between 1963 and 1987, moreover, the total Ice cover on Mt. Kenya in Africa decreased by 40 percent.

Noting the local impacts of the glacial retreat, the authors wrote: "The loss of these valuable hydrological stores may result in major economic and social disruptions in those areas dependent upon the glaciers for hydrologic power and fresh waters."

The glacial ice cores, moreover, provide an invaluable record of past temperature changes in the earth’s climate. But in a paper titled "Glaciological Evidence for Recent Warming at High Elevations," Thompson and Mosley-Thompson wrote, that record is becoming obliterated by the warming of the atmosphere. In that 1995 report, they explained that ice cores "from diverse locations, such as Antarctica, Greenland, the Tibetan Plateau and the Andes...have been [used] to produce a high resolution global perspective of climate for the past 1000 years...Unfortunately, due to the unprecedented warming occurring at high elevations in the tropics and subtropics, many of these valuable archives are in imminent danger of being lost."

Citations: "Meltdown warning as tropical glaciers trickle away," New Scientist, June 24, 1995. Also: "Late Glacial Stage and Holocene Tropical Ice Core Records from Huascaran, Peru," by Lonnie G. Thompson and Ellen Mosley-Thompson, Science, Vol. 269, July 7, 1995. Also: "Glaciological Evidence for Recent Warming at High Elevations, p. 209-210. Prepared by L. Thompson and E. Mosley-Thompson for 76th American Meteorological Society Annual Meeting: Symposium on Environmental Applications.