The wandering of Earth’s north magnetic pole, the location where the magnetic field points vertically downwards, has long been a topic of scientific fascination. Since the first in situ measurements in 1831 of its location in the Canadian arctic, the pole has drifted inexorably towards Siberia, accelerating between 1990 and 2005 from its historic speed of 0–15 km yr−1 to its present speed of 50–60 km yr−1. In late October 2017 the north magnetic pole crossed the international date line, passing within 390 km of the geographic pole, and is now moving southwards. Here we show that over the last two decades the position of the north magnetic pole has been largely determined by two large-scale lobes of negative magnetic flux on the core–mantle boundary under Canada and Siberia. Localized modelling shows that elongation of the Canadian lobe, probably caused by an alteration in the pattern of core flow between 1970 and 1999, substantially weakened its signature on Earth’s surface, causing the pole to accelerate towards Siberia. A range of simple models that capture this process indicate that over the next decade the north magnetic pole will continue on its current trajectory, travelling a further 390–660 km towards Siberia.