Earth's poles may switch
Jan 29, 1999
The Earth's magnetic field may flip towards the end of the next millennium according to Danish geophysicists, exposing the Earth to harmful cosmic radiation in the process. In the past century, the magnetic north pole has moved over 1000 km towards the geographical north pole, and over the past decade the strength of the magnetic field has fallen by 1%. New measurements made in Greenland by the Danish Meteorological Institute (DMI) show that the magnetic north pole is moving northwards at 20 km a year - 2 km a year faster than 12 months ago.
"This is certainly the quickest movement since we started measurements in Greenland in 1928, " says Torsten Neubert, who heads DMI's Solar-Terrestrial Physics Department. Neubert thinks that this acceleration points to a switching of the magnetic poles, perhaps within the next thousand years, something that could have dire consequences. "In the period up to a reversal, the Earth's magnetic field would lose its strength and would no longer be able to protect the Earth from radiation coming from space - we could be exposed to violent cosmic radiation, " says Neubert. Such radiation would affect navigation as well as the production of semiconductors.
However, not all geophysicists are convinced. "I wouldn't say that the northward movement of the magnetic pole is a sign that the field is about to reverse, " says a sceptical Jeremy Bloxham, an Earth and planetary scientist at Harvard University in the US. He thinks that the pole would have to be travelling towards the equator in order to flip. Neubert admits that the case for a switch in the magnetic field is unproven and says that the field is a chaotic system and therefore difficult to predict.
The new Danish Ørsted satellite may make prediction a little easier by looking at the whole of the Earth's magnetic field, rather than just the poles. Due to be launched in the coming weeks, it should give researchers more accurate data on the orientation and strength of the field. Bloxham, however, believes that more accurate data will not point to a reversal. "I think the chances are that it will not happen, " he says. "It's a highly erratic process - there have been intervals of tens of millions of years without reversals." But Neubert is looking forward to a reversal. "It would be an exciting time, " he says.