Earth's Core, Magnetic Field Changing Fast, Study Says

Kimberly Johnson
for National Geographic News June 30, 2008 Rapid changes in the churning movement of Earth's liquid outer core are weakening the magnetic field in some regions of the planet's surface, a new study says.

"What is so surprising is that rapid, almost sudden, changes take place in the Earth's magnetic field," said study co-author Nils Olsen, a geophysicist at the Danish National Space Center in Copenhagen.

The findings suggest similarly quick changes are simultaneously occurring in the liquid metal, 1,900 miles (3,000 kilometers) below the surface, he said.

The swirling flow of molten iron and nickel around Earth's solid center triggers an electrical current, which generates the planet's magnetic field.

The study, published recently in Nature Geoscience, modeled Earth's magnetic field using nine years of highly accurate satellite data.

Flip-Flop

Fluctuations in the magnetic field have occurred in several far-flung regions of Earth, the researchers found.

In 2003 scientists found pronounced changes in the magnetic field in the Australasian region. In 2004, however, the changes were focused on Southern Africa.

The changes "may suggest the possibility of an upcoming reversal of the geomagnetic field," said study co-author Mioara Mandea, a scientist at the German Research Centre for Geosciences in Potsdam.

Earth's magnetic field has reversed hundreds of times over the past billion years, and the process could take thousands of years to complete.

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