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Polar Wander Linked to Climate Change

According to the authors1 space geodetic observations of Polar motion indicate that the average annual pole position began to drift towards the east around 2005, which was an abrupt departure from the direction it had been drifting over the past century. The Gravity Recovery and Climate Experiment (GRACE) took satellite gravity measurements which indicated that about 90 % of this change results from accelerating polar ice sheet melting, as well as melting mountain glaciers and related sea level rise. It is indicated that the close relationship between mass redistribution and long-term polar motion, established using data from GRACE, that polar motion data that is accurately measured offers an additional tool for monitoring ice melting on a global scale and sea level rise, which should be useful for bridging the gap that is anticipated between GRACE and follow-up satellite gravity missions.

Lovett2

According to Lovett2 the geographic poles of the Earth are being changed by global warming, as reported on by the study by Chen et al.1 of the University of Texas. The results demonstrate that the North Pole was helped to shift several centimetres to the east per year since 2005 by increased Greenland ice melt, and though to a lesser extent, also in other parts of the world.

The pole had drifted to the southeast towards Labrador, Canada, at about 2 milliarcseconds, roughly 6 cm, per year, then in 2005 the pole changed course and accelerated to more than 7 milliarcseconds per year towards Greenland.

Rosen3

The Earth has 2 north poles, the magnetic north pole to which compass needles point, and the true geographic North Pole, the axial pole around which the Earth rotates. The wandering of the magnetic north pole have been known of for a long time, at the present its northern end is situated to the northwest of Greenland, but now there have been surprising reports about the movement of the geographic North Pole, which is less well known than the movements of the magnetic pole, It has been found that it is now heading for the centre of the Greenland Ice Sheet.

For more than 100 years geodetic measurements of the axial North Pole have been collected, and these measurement show that small seasonal wobbles are superimposed on a slow, about 6 cm per year, southward migration of the axial position. The short-term variations have been attributed to seasonal changes of the pattern of wind and ocean circulation, and these change the drag forces that are acting on the surface of the spinning Earth. It has been believed that the slow drift is most likely due to the rebounding of the Canadian bedrock following the demise of the Laurentide Ice Sheet that occurred at the close of the last glacial phase more than 10,000 BP. The orientation of the rotational axis of the Earth moves to regain balance when the mass distribution on the Earth's surface changes, as occurs when extensive continental ice sheets disintegrate, by tipping towards the site of the loss of mass. It has now been reported that the position of the geographic North Pole has veered sharply to the east at Almost 27 cm/year since 2005 (Chen et al., 2013)1.

The acceleration of ice loss from the Greenland Ice Sheet over the last decade is suggested by the researchers to be the trigger for the abrupt direction change. This hypothesis is supported by the ice mass measurements by the GRACE  satellite. The majority of the polar motion is explained by the observed rates of ice loss from Greenland, after accounting for other known factors. The authors1 also highlight the reciprocal nature of their conclusion, given extreme precision of the identification of polar location, and they also suggest their study reaffirmed the recent acceleration of ice melting over polar ice sheets and mountain glaciers.

Sources & Further reading

  1. Chen, J. L., C. R. Wilson, J. C. Ries, and B. D. Tapley. "Rapid Ice Melting Drives Earth's Pole to the East." Geophysical Research Letters 40, no. 11 (2013): 2625-30.
  2. Lovett, Richard A., 4 Oct 2013, Polar Wander Linked to Climate Change, Nature, News.
  3. Rosen, Julia, October 2013, Polar Melting affects Earth's Axis of Rotation, Earth.

Links

  1. Rapid Ice Melting Drives Earth's Pole to the East
Author: M. H. Monroe
Email:  admin@austhrutime.com
Last updated  06/10/2013
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                                                                                           Author: M.H.Monroe  Email: admin@austhrutime.com     Sources & Further reading