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Bleak outlook for ice
The news on the cryosphere hasn’t been good at this year’s EGU meeting, with poor prognoses for mountain glaciers, Arctic ice shelves and permafrost.
The situation seems particularly bleak for the ice shelves in Canada’s far north. Luke Copland of the University of Ottawa, Canada, has been studying the northern coast of Ellesmere Island. Records from an expedition to the region in 1906 indicate that the ice shelves had an area of 10,000 square km. But by early 2008 there were only five ice shelves left, with a total area one-tenth of the figure a century ago. And by September of 2008 the Markham ice shelf had disappeared, leaving four ice shelves with a total area of just 750 square km.
Copland says there are several reasons for the changes, including the increase in winter temperatures of one degree C per decade, which prevents the ice shelves from rebuilding over the winter, the decreased extent of sea ice, which used to protect the outside edges of the shelves from tides and waves, and very warm summers and high winds in 2005 and 2008. He reckons it would take centuries to rebuild the ice shelves even if we stabilize temperatures at current levels and he would be surprised if the Arctic ice shelves survive.
Smaller and thinner than those in the Antarctic, these northern hemisphere ice shelves have become disconnected from the glaciers that created them. This has allowed freshwater pools around 40 m deep and known as epishelf lakes to build up behind the ice shelves on top of oceanic water, creating unique ecosystems. These ecosystems will disappear if the remaining Arctic ice shelves go.
Meanwhile Wilfried Haeberli of the University of Zurich, Switzerland, reported how he believes it’s a realistic scenario that all mountain glaciers could have disappeared by 2050. The Pyrenees have lost 90% of their ice cover over the last few decades, for example. This will have big implications for water as rivers such as the Rhone and Rhine gain most of their water from glacier melt in July and August. “Most of my students will experience the loss of most of the European glaciers by the middle of the century,” said Haeberli. “There is practically no hope for glaciers in the mountains.”
