A pair of papers in Science this week refines the understanding of the acceleration of glacier flow from lubrication by meltwater. The bottom line:
Now a two-pronged study–both broader and more focused than the one that sounded the alarm–has confirmed that meltwater reaches the ice sheet’s base and does indeed speed the ice’s seaward flow. The good news is that the process is more leisurely than many climate scientists had feared. “Is it, ‘Run for the hills, the ice sheet is falling in the ocean’?” asks glaciologist Richard Alley of Pennsylvania State University in State College. “No. It matters, but it’s not huge.” The finding should ease concerns that Greenland ice could raise sea level a disastrous meter or more by the end of the century. Experts remain concerned, however, because meltwater doesn’t explain why Greenland’s rivers of ice have recently surged forward.
A remarkable excerpt:
The meltwater monitoring caught a 4-kilometer-long, 8-meter-deep lake disappearing into the ice in an hour and a half. As theorists had supposed, once the lake water was deep enough, its weight began to wedge open existing cracks, which only increased the weight of overlying water on the crack tip and accelerated cracking downward. Once the main crack reached the bottom of the ice, heat from churning water flow melted out parts of the fracture, and drainage took off. The lake disappeared in about 1.4 hours at an average rate of 8700 cubic meters per second, exceeding the average flow over Niagara Falls. That’s almost four Olympic pools a second.
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1 thought on “Glacier News”
I just noticed this interesting new paper on the GIS response speed during the last two deglaciations. I suppose the good news is that it’s not proof as such of a decadal response.
Good site, BTW. I read everything.