Recently, the weakening of the Earth’s magnetic field received a lot of attention. One scenario is that a magnetic field reversal might occur, which is expected to have severe impacts for life on Earth. At the same time we know that man-made global warming is taking place at full speed. In this Great Debate we discuss the following questions: What are the consequences of increased particle fluxes of severe space weather events for life on Earth? What can we learn from other rocky planets in the solar system and beyond? The effects will be put into perspective with the time scales, physical processes and consequences of the different scenarios of anthropogenic climate change that depend on how successful climate change mitigation will be in the coming years.