| Summary: | size of Manhattan broke off Greenland’s northwestern coast and began drifting out to the sea. At nearly 100 square miles, this was the largest iceberg to appear in Arctic waters since 1962 and a fresh indicator that Greenland’s frozen landscape is undergoing significant changes. 1 Originally part of the much larger Petermann glacier, which flows down from Greenland’s interior into a coastal fjord, the iceberg detached for unknown reasons. It could be that ordinary glacial dynamics were at work, and indeed, Petermann glacier “calves ” (breaks off) icebergs routinely, although generally not ones so large as this. But the unusual size of the iceberg also might signal a response to global warming, and that’s what worries scientists. Accelerated melting of the glaciers and other frozen masses that make up Earth’s cryosphere has become a widespread phenomenon. Apart from what’s happening in Greenland, coastal glaciers also are thinning off West Antarctica, where an enormous ice sheet containing enough water to raise sea level by more than 20 feet has attracted growing concern. Meanwhile, a vast percentage of the world’s land-based glaciers also are in retreat, according to Richard Armstrong, a senior research scientist at the National Snow and Ice Data Center (NSIDC) at the University of Colorado, Boulder. “There’s a lot of regional variation, so there are some exceptions to the trend, ” Armstrong says. “But in general, the Earth is warming, and glaciers are shrinking in most areas. ” Likewise, the human health implications of the world’s changing ice cover vary regionally. Melting water streams from an iceberg in Ilulissat Icefjord, Greenland. The iceberg calved from Sermeq Kujalleq (in Danish: Jakobshavn Isbrae), one of the world’s fastest-moving and most active glaciers. Sermeq Kujalleq nearly doubled its calving
|
|---|