Glacier melting a key clue to tracking climate change
Glaciers now occupy the center stage in the debate over causes and impacts of climate change.
The world has become far too hot for the aptly named Exit Glacier in Alaska.Skip to next paragraph
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Like many low-altitude glaciers, it's steadily melting, shrinking two miles over the past 200 years as it tries to strike a new balance with rising temperatures.
At the Kenai Fjords National Park south of Anchorage, managers have learned to follow the Exit and other glaciers, moving signs and paths to accommodate the ephemeral rivers of blue and white ice as they retreat up deeply carved valleys.
"Some of the stuff is changing fast enough that we now have signs on moving pedestals," said Fritz Klasner, natural resource specialist at Kenai Fjords.
The vast amounts of water stored in glaciers play crucial roles in river flows, hydropower generation and agricultural production, contributing to steady run-off for Ganges, Yangtze, Mekong and Indus rivers in Asia and elsewhere.
But many are melting rapidly, with the pace picking up over the past decade, giving glaciers a central role in the debate over causes and impacts of climate change.
That role has come even more sharply into focus after recent attacks on the U.N.'s climate panel, which included a wrong estimate for the pace of melting for Himalayan glaciers in a major 2007 report.
The report said Himalayan glaciers could all melt by 2035, an apparent typographical error that stemmed from using literature not published in a scientific journal.
Climate skeptics seized on the error and used it to question the panel's findings on climate change.The evidence for rapid glacial melting, though, is overwhelming.
The problem is no one knows exactly what's occurring in the more remote Himalayas and parts of the Andes. Far better measurements are crucial to really understand the threat to millions of people downstream.
"There is no serious information on the state of the melting of the glaciers in the Himalayan-Tibetan complex," Kurt Lambeck, President of the Australian Academy of Science, told a climate science media briefing in late February.
The high altitude and remoteness of many glaciers in the Himalayas and Andes is the main reason.
DATA IN A DEEP FREEZE
In Europe and North America, glaciers are generally more accessible and there are more trained people to study them. Switzerland's Aletsch glacier, the largest in the Alps, has been retreating for about 150 years. But the glacier, which feeds the River Rhone, still stores an estimated 27 billion tonnes of ice, according to www.swissinfo.ch.