FAIRBANKS — It might be time for Alaskans to start turning the compass a bit less to account for planet Earth’s wandering magnetic poles.
A five-year update to a magnetic model released Monday shows the north magnetic pole is continuing its inconsistent drift westward toward Siberia. The model, calculated by the U.S. and British governments, is used for technology such as military fighter jets and consumer smartphones.
For Fairbanks, the World Magnetic Model puts the declination, the difference between magnetic and geographic north, at 18.8 degrees east. The declination continues to shrink as the magnetic pole moves about half a degree toward the geographic pole, at the rate it’s now traveling.
For backcountry travelers using a compass to navigate, small changes to the magnetic declination don’t make a significant difference because it’s hard to follow a bearing to within a few degrees. But over decades, Fairbanks’ declination has changed enough to make the labeled declination on old U.S. Geological Survey maps obsolete.
Usually navigators turn the dial on their compass to account for the difference between true and magnetic north. But at the Alaska Orienteering Club in Anchorage, Ian Moore adjust the maps to align them with magnetic north.
“It has changed pretty dramatically during our lifetime,” he said. “Every few years, I go in and rotate the maps another degree or so.”
The poles move because of moving liquid metal under the Earth’s crust. The World Magnetic Model is based on data collected from satellites and from field stations, according to Arnaud Chulliat, the project’s team leader at the National Geophysical Data Center in Boulder, Colorado. It’s one of several models use to calculate the location and movement of the magnetic poles.
”It (the north magnetic pole) accelerated in the 1990s, and it’s now moving about 55 kilometers per year,” he said.
In general, Alaska is one of the regions where the magnetic declination is changing most quickly because of its proximity to the moving magnetic pole. Since scientists have measured the north magnetic pole, the pole has moved northwest from northern Canada to its current location near the geographic pole, he said.
For more information about the World Magnetic Model, including a magnetic declination calculator, go to ngdc.noaa.gov/geomag/WMM/DoDWMM.shtml
Magnetic declination in Alaska and elsewhere
The ’ symbol indicates a minute, 1/60 of a degree
• Fairbanks 18° 48’ E, changing by 0° 25’ W per year
• Ketchikan: 19° 15’ E, changing by 0° 14’ W per year
• Barrow: 16° 8’ E, changing by 0° 32’ W per year
• Adak: 5° 13’ E, changing by 0° 9’ W per year
• Minneapolis 0° 26’ E, changing by 0° 4’ W per year
• Johannensburg, South Africa, 18° 29’ W, changing by 0° 6’ W per year
• St. Petersburg, Russia, 10° 18’ E changing by 0° 9’ E per year
Contact outdoors editor Sam Friedman at 459-7545. Follow him on Twitter: @FDNMoutdoor.