Posted: Thursday, May 6, 2021 13:29 You may not know it, but the GPS system in your car, and the apps in your phone depend on the magnetic field of the Earth. But what happens if that field moves? As aviation and marine and all navigation systems also depend on it, potentially there could be trouble. Well the field is on the move, and a new study suggests human activity is likely behind it. In our terms, i.e. the average citizen, that movement is not really noticeable at all, but for navigation it is very important, and in scientific terms, it’s huge.