Reader View from the Solent writes:
Global warming shifts the Earth’s poles. North Pole heads for Greenland
“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. (which amounts to 21cm or ~8 1/4″- Anthony)
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.
With global warming introducing that extra wobble, it is easy to create a model to project what effect global warming will have on the Earth in the future. /sarc – Anthony