Changes in rainfall patterns are a direct consequence of the current climate change. Climate projections indicate an intensification of extreme rainfall events, which will directly affect social, ecological, and economic systems. One of the greatest challenges of climate science is to understand, model, and predict the variability of floods. The uncertainties in projected rainfall are still high, and even higher in Mediterranean areas where the climate is characterized by extreme and sudden rainfall events. The instrumental record is too short to correctly estimate flood return periods. Thus, geological records are required to better understand the long term variability, at millennial to decadal scales, of natural extreme flood events. MODKARST is a MSCA-GF project awarded by the European Union, to develop a quantitative flood database for the Western Mediterranean realm based on speleothems. The action plans to infer past flood events from the last 18 ka based on detrital layers recorded in stalagmites from 5 different caves in the north of Spain, in combination with karst hydraulic models and water-level monitoring. MODKARST will help to better disentangle the relation between flood recurrence and climate changes, and will shed light on how to better predict the variability of floods in the context of present-day global warming.