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North Pole shifts due to global warming

 

The North Pole has shifted east because of ice sheet loss caused by rising temperatures, a new study published in Geophysical Research Letters has found, according to the scientific journal Nature.

The pole drifted southeast toward northern Labrador, Canada, at a rate of about 6 centimeters per year between 1982 and 2005. But since 2005, the direction and speed of the pole's journeychanged. It started moving rapidly east towardsGreenland at a rate of more than 21 centimeters per year.

There has been huge ice sheet loss in the polar regions due to global warming.

The study was carried out by scientists from the University of Texas, Austin, using data collected by NASA's Gravity Recovery and Climate Experiment (GRACE).

Earth's two geographic poles do not have a fixed location. As the distribution of snow, rain and humidity changes every year, the poles too wobble around, usually in a circular manner. Besides this seasonal drift, there is a long range movement which scientists believe is driven by continental drift - the movement of land plates relative to each other.

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, Nature said. The researchers led by Jianli Chen, a geophysicist, used GRACE data to model how melting icecaps affect Earth's mass distribution. They found that more than 90% of the post-2005 polar shift was because of increasing ice loss and sea-level rise.

The explanation for this is that when mass is lost in one part of a spinning sphere, its spin axis will tilt directly toward the position of the loss, according to Erik Ivins, a geophysicist at NASA's Jet Propulsion Laboratory in PasadenaCalifornia quoted by Nature. This is exactly what was observed in the case of the North Pole.

These findings have opened the way to estimate long term ice loss by studying polar drift. Scientists can locate the north and south poles to within about 0.9 millimeters by using Global Positioning System measurements to determine the angle of the Earth's spin. Since polar shifts have been recorded for almost a century, Nature says, it is possible to study ice losses for that period. Direct records of ice loss in Polar regions do not go back that much in time.

Times of India (15-05-2013)