The Arctic magnetic pole is really the south pole of Earth's magnet
A compass needle's north end swings toward the Arctic, and opposite poles attract. So the magnetic pole near Canada's Ellesmere Island is, strictly speaking, the south pole of Earth's magnetic field. The naming quirk dates from when compasses were among the first uses of magnets, so Earth defined the poles of magnets rather than the reverse.
The field is produced deep underground. Heat escaping from the outer core drives convection in molten iron and nickel, and the moving metal generates electric currents that sustain a magnetic field, a self-running process called a geodynamo. Near the surface it looks roughly like a giant bar magnet tilted about 11 degrees from the spin axis, and that simple dipole accounts for 80 to 90 percent of the field in most places. The rest is irregular, which is why compasses point neither at the geomagnetic poles nor exactly at the dip poles.
Strength varies. The 2019 international reference model recorded about 60,000 nanotesla over Siberia and about 30,000 over Brazil, while a strong fridge magnet manages around 10,000 microtesla, far stronger. The weakest patch is the South Atlantic Anomaly over South America. The poles also drift: the northern one has moved up to 40 kilometres in a year, travelling from Cape Adelaide on the Boothia Peninsula in 1831 to 600 kilometres from Resolute Bay by 2001. Every few hundred thousand years, on average, the field flips entirely, and those reversals are frozen into volcanic rock as stripes along mid-ocean ridges, helping geologists date rocks and track drifting continents.
Out in space the field forms the magnetosphere, pushed to about 10 Earth radii on the side facing the Sun and stretched into a tail beyond 200 radii on the night side. It holds off the solar wind, charged particles streaming from the Sun at 200 to 1000 kilometres per second, which would otherwise erode the atmosphere and its ozone. Mars shows the stakes: calculations suggest its atmosphere was almost entirely lost after its magnetic field faded.
Some particles leak in, bouncing between the poles several times a second. Those that strike the upper atmosphere light up the aurorae. Living things exploit the field as well, from certain bacteria to pigeons, and people have used compasses to find direction since the 11th century.
Source: Earth's magnetic field
