Thursday, June 13, 2013

Climate Change Contributes To Shifting Poles

Geographic North & South\




Melting Ice: “Scientists suspect that melting ice has tilted the North Pole towards Greenland,” Nature reports.Photo Credit: Patrick Robert; Corbis
Source: Nature


An article, by Richard A. Lovett, in Nature says that scientists have recorded that both
the North and South poles are shifting more than usual, a result attributed to climate change.
Global warming is changing the location of Earth’s geographic poles, according to a study in Geophysical Research Letters1.Researchers at the University of Texas, Austin, report that increased melting of the Greenland ice sheet — and to a lesser extent, ice loss in other parts of the globe — have helped to shift the North Pole several centimetres east each year since 2005. “There was a big change,” says geophysicist and lead author Jianli Chen.
Between 1982 and 2005, the pole drifted southeast towards 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 towards Greenland at a rate of more than 7 milliarcseconds per year.Scientists have long known that the locations of Earth’s geographic poles are not fixed. Over the course of the year, they shift seasonally as Earth’s distributions of snow, rain and humidity change. “Usually [the shift] is circular, with a wobble,” says Chen.
But 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 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 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 ice caps 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.
This information on polar shift can help scientists determine more accurately the amount of ice loss around the areas of the poles, since they have established a correlation between the two. That ice loss has been accelerating since 2005 is not good news; this shows that climate change is a real threat to the earth's health and stability.

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You can read the rest of the article at [Nature]