Western Greenland's Jakobshavn Glacier, dubbed the world's fastest-flowing glacier is featured in this video segment adapted from NOVA scienceNOW. Scientists attempt to explain why this glacier is moving at a rate that far exceeds the average speed of glaciers and is contributing to a rise in global sea level. Their explanation revolves around the recent discovery that increased meltwater caused by global warming flows down holes in the glacier. Once it reaches the underlying rock, the theory goes, this water actually lubricates and lifts the glacier, allowing it to glide downhill with decreased resistance.
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