This article argues that research is urgently needed to improve our understanding of the occurrence rates of severe geomagnetic storms. It was written in response to an invitation from the journal Nature and published in their Comments series, which is intended to stimulate debate on future research needs. The article reviews our current understanding of these storms and the threat that they pose to technologies that underpin critical national infrastructures (e.g. power grids, satellite-based services, …). It also outlines current efforts to mitigate the risks posed by geomagnetic storms, both though better engineering that builds more robust infrastructures and through development of better warning systems that exploit current scientific skills to monitor, and forecast the arrival at Earth of, the solar ejecta that cause severe geomagnetic storms. Finally the article outlines areas in which research can further improve these scientific skills, e.g. improved access to historical datasets, better physics-based modelling, more complete understanding of the physics at work in severe events.