An ice island four times the size of Manhattan that broke off Greenland is not clear evidence of global warming, but is part of a broader "disturbing picture," scientists told a Congressional committee.
The biggest such event in the Arctic in nearly 50 years, the ice island's separation from the tip of Petermann glacier is part of a normal process, and the glacier is losing the majority of its mass where ice meets water, said Andreas Muenchow, Professor of Ocean Science and Engineering at the University of Delaware.
Muenchow said he had expected an ice chunk to break off from the Petermann Glacier, one of the two largest remaining ones in Greenland, because it had been growing in size for seven or eight years.
He said it was there is not enough data available to judge whether the event occurred due to global warming because records on the sea water around the glacier have only been kept since 2003.
Although the ice island's formation cannot be viewed as definite evidence of global warming, it is part of a greater phenomenon of warming that is causing ice sheets to melt, said University of Maryland Senior Research Scientist, Robert Bindshadler.
Scientists have said the first six months of 2010 have been the hottest globally on record. Many scientists say elevated levels of man-made greenhouse gases are pushing temperatures higher.
Committee Chair Edward Markey called for governments around the world to unite to curb further climate change. "A crime against nature is being committed in Greenland and in the Antarctic, and all of humanity will suffer," he said.
The ice island could fuse to land, break up into smaller pieces, or slowly move south where it could block shipping, Muenchow said.