What is a geomagnetic storm? How does it affect Earth? Geomagnetic storms are disturbances to Earth’s giant magnetic field that occur when there’s a significant exchange of energy from the solar wind to the space environment surrounding Earth. Geomagnetic storms can be caused by several different solar events, including coronal mass ejections. These storms can cause fluctuations in Earth's ionosphere (part of the upper atmosphere) that can modify and interrupt the path of radio and GPS signals!