Oceans Currents Behind Earth's Magnetism

Earth’s Magnetic field, long thought to be generated by molten metals swirling around its core, may instead be produced by ocean currents, according to controversial new research published last week.

It suggests that the movements of such volumes of salt water around the world have been seriously underestimated by scientists as a source of magnetism.

If proven, the research would revolutionize geophysics, the study of the Earth’s physical properties and behaviour, in which the idea that magnetism originates in a molten core is a central tenet. Earth’s magnetic field is vital for life, extending tens of thousands of miles into space and protecting the planet against radiation that would otherwise burn away the atmosphere and oceans. Image shows how Earth's Magnetic field saves Earth from Solar Wind..

However, its origin was a mystery until early last century when Albert Einstein said understanding the phenomenon was one of science’s most important tasks. This provoked a debate which concluded with scientists agreeing that magnetism must originate in the Earth’s core. “Everyone accepted this, but in reality there has never been any proof,” said Gregory Ryskin, associate professor of chemical and biological engineering at Northwestern University in Illinois. “It is just an idea we have accepted for a long time without questioning it enough.”

His research suggests that Earth’s magnetism is actually linked to ocean movements. The salt in seawater allows it to conduct electricity, meaning it generates electrical and magnetic fields as it moves. The findings, published by Britain’s Institute of Physics last week, are likely to cause a fierce scientific debate.

Existing theories explain Earth’s magnetism by suggesting that the centre of the planet comprises a white-hot solid iron ball about 1,500 miles in diameter, surrounded by an outer shell of liquid metal a further 1,400 miles thick. As the liquid iron in that shell is heated by the inner core it becomes less dense and rises upwards, to be replaced by cooler material from above. The resulting swirls of molten metal create electric currents that in turn produce the planet’s magnetic field, the conventional theory suggests.

Changes in ocean circulation may also, Ryskin said, explain the curious reversals shown by Earth’s magnetic field, in which the north and south magnetic poles have suddenly flipped over. This last happened 780,000 years ago. If Gregory Ryskin is right, then Climate Change, predicted to alter the strength and course of ocean currents, could also alter the planet’s magnetic field.
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