Groundwater sources supply fresh drinking water to almost half of the World's population and are a main source of water for irrigation across world. Characterization of groundwater resources, surface groundwater interactions and their link to the global water cycle and modern global change are important themes in hydrogeological research, whereas little attention has been given to the relation between groundwater and past climate variations. A groundwater system's history is vital to assess its vulnerability under future and potentially adverse climatic changes. The scientific initiative Groundwater and Global Palaeoclimate Signals (G@GPS) investigates major recharge periods of large groundwater aquifers worldwide. We describe the findings for a major basin on each permanently inhabited continent and one with coastal influences in Australia. As palaeo-signals in groundwater are inherently low-resolution records, they can only be related to considerable amounts of recharge. Long periods with substantial groundwater recharge ought to be well identifiable in terrestrial records. Correlation with regional and global climate records may give ideas of the conditions under which such large amounts of recharge were initiated.