Magnetic north, the point at the top of the Earth that determines compass headings, is shifting its position at a rate of about 40 miles per year. In geologic terms, it’s racing from the Arctic Ocean near Canada toward Russia.
As a result, everyone who uses a compass, even as a backup to modern GPS navigation systems, needs to be aware of the shift, make adjustments or obtain updated charts to ensure they get where they intend to go, authorities say. That includes pilots, boaters and even hikers.
Although the magnetic shift has little impact on the average person and presents no danger to the Earth overall, it is costing the aviation and marine industries millions of dollars to upgrade navigational systems and charts.
Why is magnetic north shifting?
The Earth’s core of hot liquid iron is constantly moving. That motion, combined with forces such as the Earth’s rotation, dictate the position of magnetic north, not to be confused with geographic north, or the North Pole.
“Magnetic north is shifting all the time; it’s a continuous process, not an event,” said Jeffrey Love, a geophysicist with the U.S. Geological Survey Geomagnetism Program, based in Golden, Colo.
Over the past century, the shift has been increasing in speed. It went from creeping as slow as nine miles per year in the early 1900s to more than 35 miles per year in the 2000s. However, that acceleration also is part of natural cycle, Love said. “In 10 to 20 years from now, it might be slowing down,” he said.
“Currently, the shift creates about a one-degree difference in compass direction every five years,” Love said.
The Federal Aviation Administration evaluates airport runway numbers every five years, said Kathleen Bergen, FAA spokeswoman.
The FAA could not say how many airports are affected. However, scores of large and small airports in the United States have either changed or plan to change their runways’ numbers, which are based on compass directions.
Because GPS navigation draws on satellites, it has no reliance on magnetic north. On the other hand, satellites and GPS systems can malfunction. For that reason all pilots and boaters should keep a compass handy as backup.
The magnetic compass is what gets you home in your boat or plane when everything else quits. It’s a very valuable piece of equipment but should not be relied on solely. Large ships and planes have sophisticated electronic navigation systems, but the vast majority of small boats and planes have magnetic compasses and rely on them heavily.
Boaters should always bring updated charts, showing the latest corrections for the magnetic north shift, even if they have a GPS.
To learn more about the using the magnetic compass to navigate, check out the Nautical Know How Coastal Navigation Course. You will learn all aspects of navigation including how to use your magnetic compass.
Humans aren’t the only ones affected by magnetic north. Birds that fly south for the winter and some sea turtles that migrate from Africa to South America must learn to adjust their senses so they end up migrating in the right direction.