14 DAY TRIAL // Is Earth's magnetic field about to reverse? It has been steadily weakening over the last century and a half and some scientists started to worry about it. If that happens, Earth will temporarily lose its protection from solar winds.
But a new study based on the data collected by past explorers such as Captain Cook shows that the concerns are probably unfounded. The weakening in the magnetic field seems to be a mere fluctuation and not a long-term trend.
The method of directly measuring Earth's magnetic field was invented in 1837 by the mathematician Carl Friedrich Gauss. However, explorers kept highly rigorous logs and used the sun and stars to judge the accuracy of their compasses. This enables scientists to deduce the Earth's magnetic field in their days.
Moreover, archaeological finds also provide information: pottery and bricks contain minerals which preserve the direction of the magnetic field that existed at the time when they were heated. These artifacts give scientists a rough idea of Earth's magnetic field strength and direction.
Researchers at the University of Leeds in the United Kingdom led by geophysicist David Gubbins took all this information into account and managed to put together a magnetic history of the Earth dating back to the 16th century. And they found almost no change in Earth's magnetic field strength between 1590 to 1840 - in contrast to the 10% decline that's happened since 1840.
However, previous field reversals (inferred from examining paleontological and archaeological remains) are known to have been preceded by sharp dips in magnetic intensity. Gubbins notes that the overall level of field strength today is higher than it has been prior to past flips, so an imminent reversal is unlikely. It simply doesn't decrease fast enough to be a sign of magnetic reversal. This decrease is more likely a sign of a mere random fluctuation.