Wednesday, May 15, 2013

The North Pole - It's a Moving Target

The north pole is on the move and, according to scientists, it's moving because of climate change and the loss of Arctic ice.

From 1982 to 2005, the pole drifted southeast toward northern Labrador, Canada, at a rate of about 2 milliarcseconds —or roughly 6 centimetres — per year. But in 2005, the pole changed course and began galloping east toward Greenland at a rate of more than 7 milliarcseconds per year.

...underlying the seasonal motion is a yearly motion that is thought to be driven in part by continental drift. It was the change in that motion that caught the attention of [U. Texas geophysicist Jianli] Chen and his colleagues, who used data collected by NASA’s Gravity Recovery and Climate Experiment (GRACE) to determine whether ice loss had shifted and accelerated the yearly polar drift.

GRACE’s twin probes measure changes in the Earth’s gravity field, which can be used to track shifts in the distribution of water and ice.  Chen’s team used GRACE data to model how melting icecaps affect Earth’s mass distribution. They found that recent accelerated ice loss and associated sea-level rise accounted for more than 90% of the post-2005 polar shift.

The results suggest that tracking polar shifts can serve as a check on current estimates of ice loss, says Erik Ivins, a geophysicist at NASA’s Jet Propulsion Laboratory in Pasadena, California. When mass is lost in one part of a spinning sphere, its spin axis will tilt directly toward the position of the loss, he says — exactly as Chen’s team observed for Greenland. “It’s a unique indicator of the point where the mass is lost,” says Ivins.

But, of course, we don't have to concern ourselves with this because it's about science and ice and stuff and that has nothing to do with pipelines and supertankers and bitumen and the things that matter.

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