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Coast glaciers surgeAuthor: Paul Madgwick The West Coast's twin glaciers are surging forward again in spite of the global warming that is melting glaciers elsewhere in the world.
The ice advance at the Franz Josef Glacier and Fox Glacier is so great that the movement of up to 1m a day at Franz and 70cm at Fox is almost visible to the naked eye. "It's pushing a pile of rocks in front of it like a slow-moving bulldozer blade, so you can certainly see evidence of the advance," Franz Josef Glacier Guides director Mark Mellsop said. Across the hill at Fox Glacier, Alpine Guides managing director Mike Browne, a glacier guide for 31 years, said the advance had been especially noticeable in the past three months and was quickly swallowing up the steps and staircases cut into the ice for the guided walks. "On a pretty regular basis we're having to cut a completely new line because the old one has moved downhill," he said. For both glaciers, it is the biggest ice advance since the last major push in the mid-1990s. The anecdotal evidence of the advance has now been backed by aerial surveys by the National Institute of Water and Atmospheric Research (Niwa), which show that all the glaciers in the Southern Alps gained more ice than they lost in the 12 months to February. Niwa principal scientist Dr Jim Salinger said this year's gains were caused by more snow in the Alps, particularly from late winter to early summer last year. Over the past three years the glaciers have gained in mass, halting the declines seen between 1998 and 2002. "This past year was the seventh-largest gain since we started aerial surveys in 1977," Salinger said. He said the recent gains did not compensate for the large retreats over the past century, which were linked to a 0.7deg C increase in the regional mean temperatures. However, the West Coast glaciers have fared better in a warming climate than many other glaciers around the world. The World Glacier Monitoring Service has reported an average annual loss of 0.5m in ice thickness since 1980 for glaciers that have been monitored continuously, and said that left no doubt about the accelerating change in the world's climate. But Salinger said the New Zealand glaciers were unusual because they had their source in areas of extremely high rainfall. West of the main divide in the Southern Alps is drenched in more than 10m of rain each year. The glaciers advanced during most of the 1980s and 1990s, when the area experienced about a 15 per cent increase in precipitation, associated with more El Nino events. In most of the rest of the world (with the exception of parts of Norway), glaciers tend to be in areas of lower precipitation, so rising temperatures are affecting the glaciers there more directly and sooner. Browne said the Fox Glacier at the terminal face had grown in bulk both sideways and upward. Recent GPS measurements by a university student showed a 3m gain in ice depth in three months. "It's getting noticeably steeper at the front, which is a sign of an advancing glacier," Browne said.
http://www.stuff.co.nz/stuff/0,2106,3394705a7693,00.html
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Scientists say the difference is because of a snow gain in the Southern Alps and the Coast's rainfall.