It sounds unlikely but it's true: the magnetic north pole is moving faster than at any time in human history, threatening everything from the safety of modern transport systems to the traditional navigation routes of migrating animals.

Scientists say that magnetic north, which for two centuries has been in the icy wilderness of Canada, is currently relocating towards Russia at a rate of about 40 miles a year. The speed of its movement has increased by a third in the past decade, prompting speculation that the field could be about to "flip", causing compasses to invert and point south rather than north, something that happens between three and seven times every million years.

Already the phenomenon is causing problems in the field of aviation. Tampa International airport in Florida has just spent a month renaming its three runways, which in common with those at most US airports are identified using numbers that correspond to the direction, in degrees, that they face on a compass. "Everything had to be changed; it was a huge project," Brenda Geoghagan, a spokeswoman for the airport, said.

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The current rate of magnetic north's movement away from Canada's Ellesmere Island is throwing out compasses by roughly one degree every five years, prompting the US Federal Aviation Administration to re-evaluate runway names across the country every five years. Similar changes were recently made to runways at Fort Lauderdale and Palm Beach.

Geologists believe that magnetic north pole (which is different from the true North Pole, the axis on which the Earth spins) moves around due to changes in the planet's molten core, which contains liquid iron. They first located it in 1831, and have been attrying to follow its progress ever since.

Records indicate that the pole's location barely moved in the early decades, but in about 1904, it began tracking north-east at a rate of about nine miles a year. That speed increased significantly from about 1989, possibly because of a "plume" of magnetism deep below ground. The pole is now believed to be heading towards Siberia at about 37 miles each year. "Earth's magnetic field is changing in time. And as far as we know, it has always been changing in time," geophysicist Jeffrey Love of the US Geological Survey in Colorado told Discovery News, which investigated the issue last week.

GPS systems, which rely on satellites, have replaced compasses as the means by which the majority of professional navigators orientate themselves. But compasses are still valuable, and are widely used by hikers and other amateur map-readers. In some environments, such as underwater or beneath ground, which cannot be reached by satellite signals, they remain the only option. The oil industry, which uses magnets to determine which angle it should drill into the earth, needs to keep track of the exact location of magnetic north.

Birds that fly south for the winter, along with migratory sea creatures, could face confusion. Long-living animals, such as whales and turtles, may in future be required to recalibrate their navigational instincts.

Despite the cost and inconvenience of altering runway names, not to mention the indignity of losing magnetic north to Russia, inhabitants of North America stand to benefit from the changes in at least one respect: it will give them more opportunities to observe the aurora borealis.

No one can predict the impact of "polar reversal", during which magnetic north and south reverse, since one hasn't happened for 780,000 years, the longest stable period in the past 5 million years. Some geologists think we could be about to find out, though: they believe that the current changes to magnetic north could be the early stages of a "flip". But Mr Love says we shouldn't be too concerned. "Reversals typically take about 10,000 years to happen," he said. "And 10,000 years ago civilisation did not exist. These processes are slow, and therefore we don't have anything to worry about."