At the start of the 20th century, the magnetic North Pole sat on the edge of the Canadian Arctic, nearly as far south as 70ºN. The intervening century has seen it gradually move further north, crossing into the Arctic Ocean just before the turn of the millennium. Over this time it has also been speeding up, from around 15 kilometres annually, to now more than 50 kilometres annually. At present it sits closer to the geographic North Pole than at any point since it was first measured by James Clark Ross back in June 1831, and it is rapidly progressing towards Russia.
The precise cause of this change is extremely complicated, triggered by the unpredictable movements of vast streams of fast-moving liquid iron within the planet’s outer core. While these developments are unlikely to affect most people’s daily lives, in major industries that require robust orientation data, such as shipping and the military, the adverse consequences can be significant. As a result, the British Geological Survey (BGS) and the National Oceanic and Atmospheric Administration (NOAA) recently agreed to release an update to the 2015 version of the World Magnetic Model – which tracks the global magnetic field – a year early, as requested by the UK Ministry of Defence and the US Department of Defence.
‘This out-of-cycle release is unusual but was prompted because the map had exceeded the error of one degree average difference at high latitudes,’ explains Dr Ciaran Beggan, geophysicist at the BGS. ‘At the moment the difference between the 2015 prediction for today and where the pole is according to the new release is around 40 kilometres. By 2020 that will be 53 kilometres. This makes a difference at high latitudes, particularly if you are near the magnetic North Pole. But it would probably take more than a decade for the global map to become noticeably poor for most users. Even then it would be only wrong by a few degrees in general.’
Despite the fast-moving pole, and the need for this recent update, Beggan predicts it will be unlikely for the frequency of the updates to change going forwards, since it can take several months or even a year for each new model to be incorporated into military equipment. ‘What is actually quite strange is that the magnetic South Pole has hardly moved at all in the past 40 years,’ he adds. ‘No one is sure why that’s the case either.’
This was published in the March 2019 edition of Geographical magazine
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