Shifts in Earth's Magnetic Field Driven by Oceans?

June 22, 2009

The flow of seawater across Earth's surface could be responsible for small fluctuations in the planet's magnetic field, a controversial new study says.

If so, the research would challenge the widely accepted theory that Earth's magnetic field is generated by a churning molten core, or dynamo, in the planet's interior.

"If I am correct, then the dynamo theory is in bad shape, and all kinds of things about core dynamics also fall apart," said study author Gregory Ryskin, an associate professor of chemical and biological engineering at Northwestern University in Illinois.

Ryskin's study has attracted fierce criticism from other geophysicists, with some experts dismissing the idea as "junk" science.

"I strongly believe the new hypothesis is just nonsense," said geophysicist Robert Parker of the University of California, San Diego.

Such reactions were not entirely unexpected.

"This article is controversial and will no doubt cause vigorous debate, and possibly strong opposition, from some parts of the geomagnetism community," Tim Smith, senior publisher of the New Journal of Physics, which published Ryskin's findings, said in a statement.

Earth's Dynamo

Earth's magnetic field extends thousands of miles into space and shields surface life from the solar wind—a potentially harmful stream of charged particles emanating from the sun.

(Read "Magnetic-Shield Cracks Found; Big Solar Storms Expected.")

According to the well-known dynamo theory, Earth has a solid inner core that spins inside an outer core of molten iron. The rotating, electrically conductive liquid core is what generates the planet's magnetic field.

Unlike the static field around a bar magnet, Earth's magnetic field is constantly shifting direction. As navigators discovered centuries ago, the direction of North on a compass varies slightly depending on location.

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