"Flip" every decade? Century maybe... I've been tracking magnetic variance for ultra accurate magnetic to true North declination for about 20 years.. its accelerating rapidly, but not that fast. Normally the World Magnetic Model is updated every 5 years, they started 6mo updates a couple years ago..
Long gone are the days of a printed declination diagram on the bottom of a map being remotely accurate.
"Flip" every decade? Century maybe... I've been tracking magnetic variance for ultra accurate magnetic to true North declination for about 20 years.. its accelerating rapidly, but not that fast. Normally the World Magnetic Model is updated every 5 years, they started 6mo updates a couple years ago..
Long gone are the days of a printed declination diagram on the bottom of a map being remotely accurate.
I think 10 years is a stretch