
Changes in Earth’s magnetic field from January to June 2014 as measured by the Swarm constellation of satellites. These changes are based on the magnetic signals that stem from Earth’s core. Shades of red represent areas of strengthening, while blues show areas of weakening over the 6-month period.
Credit: ESA/DTU Space
The biggest weak spots in the magnetic field - which extends 370,000 miles (600,000 kilometers) above the planet's surface - have sprung up over the Western Hemisphere, while the field has strengthened over areas like the southern Indian Ocean, according to the magnetometers onboard the Swarm satellites - three separate satellites floating in tandem.
The scientists who conducted the study are still unsure why the magnetic field is weakening, but one likely reason is that Earth's magnetic poles are getting ready to flip, said Rune Floberghagen, the ESA's Swarm mission manager. In fact, the data suggest magnetic north is moving toward Siberia.
"Such a flip is not instantaneous, but would take many hundred if not a few thousand years," Floberghagen told Live Science. "They have happened many times in the past."[50 Amazing Facts About Planet Earth]
Scientists already know that magnetic north shifts. Once every few hundred thousand years the magnetic poles flip so that a compass would point south instead of north. While changes in magnetic field strength are part of this normal flipping cycle, data from Swarm have shown the field is starting to weaken faster than in the past. Previously, researchers estimated the field was weakening about 5 percent per century, but the new data revealed the field is actually weakening at 5 percent per decade, or 10 times faster than thought. As such, rather than the full flip occurring in about 2,000 years, as was predicted, the new data suggest it could happen sooner.















Comment: All objects with magnetic fields because of flowing currents - the Dynamo Mechanism - are subject to such pole reversals over time. The span of time between reversals depends on how fast the body is spinning, how large the body is, whether the body is solid or gaseous, and how electrically-conducting it is. The Earth and Sun differ in many ways from each other, but both have magnetic fields. The solar magnetic field reverses with every sunspot cycle (11 years) while Earth's takes much longer (300,000 years or more).
It may very well be fortuitous that the Sun, at this time, is producing less sunspots and CMEs (consistent with the onset of ice ages). A weakened magnetosphere that could reach near-zero levels would leave Earth vulnerable to extreme phenomena such as the strong geomagnetic storms, like the Carrington Event. Precipitated by an enormous sunspot in 1859, the sky turned blood red with bolts of lightning electrifying the atmosphere. Telegraph operators all over the world received electric shocks, people were electrocuted and fires were started through telegraph connections. In today's technological climate, the impact of a weak magnetic field and a strong solar delivery would be unimaginably devastating.
But that's not the real news here; the real news is that these scientists leave it open that magnetic reversals could happen much quicker than assumed, and that the next one could happen much sooner than expected.