According to a new study, the Earth's geomagnetic field that scientists have warned about for hundreds and years isn't about suddenly turning over.
Now, it appears that the magnetic North Pole will continue to be in the north, while the magnetic South Pole will stay south for at least a few thousand more years.
Andreas Nilsson, geoscientist at Sweden's Lund University, stated in an email that "In the geoologic time perspective" we are currently in a period with a very strong geomagnetic fields. "So we still have a lot of work to do before the polarity reverses."
Nilsson was the principal author of the National Academy of Sciences' research that examined a significant weakness in the geomagnetic field called the South Atlantic Anomaly (or SAA).
The study shows that the Earth's magnetic fields have been steadily declining since the 1840s when the first geomagnetic observatories were established. However, the SAA weaknesses have grown over time.
Scientists have speculated that the strength of the geomagnetic field is declining just before it reverses in its direction. This has been suggested by layers of rock that were laid over many millions of years and that show previous reversals.
New research shows that large geomagnetic anomalies were previously observed, but only in geological times.
These anomalies usually disappear a few hundred year later, and Nilsson stated that there is no indication that the SAA will be different.
Nilsson and his collaborators studied the changes in Earth's magnetic field over the past 9,000 years. They looked at iron in volcanic rocks, sea sediments, and even burned archaeological artifacts.
These include clay pots that were fired in ancient kilns thousands years ago and which may contain small amounts iron ore called magite. Nilsson stated that the magnetite lost its alignment during the firing process and that the geomagnetic fields magnetized the grains again when they cooled. This resulted in a record about the strength of the field.
The current state of Earth's magnetic field, according to the study, is very similar to the one that existed in 600 BC. This was when two major weaknesses were present over the Pacific Ocean.
However, the anomalies over the Pacific have disappeared over the next 1,000 years and it's probable that the SAA will also disappear, Nilsson stated -- probably in 300 years. This will leave a stronger and evener geomagnetic field.
Although it wouldn't be catastrophic for the geomagnetic field, it would be very inconvenient.
Scientists believe the field is created by the flow of molten steel at the Earth's core (1,800 miles below the surface). It protects against dangerous solar radiation and makes magnetic compasses function.
Geomagnetic field reverses 10 times in just 2.6 million years, according to geological studies. This was the Brunhes Matuyama reversal, which occurred around 780,000 years ago.
However, the process is tied to the movements of the molten core and scientists don't know when the next reversal will take place.
Adrian Muxworthy, an Imperial College London professor of Earth magnetism and who was not involved in the study, stated that "The Earth's magnetic fields reverse on average every 300-400 thousand years." "But it's chaotic. It's not a regular thing. It has happened for periods of up to 30,000,000 years. But it isn't a regular phenomenon.
He said that geological records from previous reversals have shown that it can take between 500 and 2,000 years for Earth's magnetic fields to fully reverse. They grow gradually weaker in one direction and stronger in the other.
Muxworthy points out that, while modern navigation systems like the Global Positioning System, (GPS) rely on orbiting satellites for their positioning, the navigational satellites still rely upon the geomagnetic fields for their alignments.
He said that it is possible that satellites located in low orbits, which are projected by the Earth’s magnetic field, could be damaged by higher amounts of solar radiation during field reversals. However, they could be made heavier to protect them.
The geomagnetic field at its weakest would be around 20 percent of the current level. This would cause increased solar radiation at surface which, though unlikely to have any significant impact on life, would increase the strength of the geomagnetic fields.
A complete field reversal would have the curious side effect of making auroras all over the planet.
Muxworthy stated that "it would actually be quite thrilling." "Just like we get the Northern Lights and the Southern Lights now, we'd be able to see them at any latitude, even over the Equator."
Nilsson warns that although his South Atlantic Anomaly study suggests that it will disappear without any trouble in a few hundred year, there is still the possibility that the Earth's magnet field will begin to reverse, even though scientists don't see any evidence that it will.