Facing climate change is a societal challenge, and calls for ambitious, transformative, and collective action. To keep global warming below 2°C, we will need to rely on negative emission technologies (NETs). A promising NET approach is Enhanced Silicate Weathering (ESW). ESW makes use of the natural weathering reaction, whereby silicate dissolution consumes atmospheric CO2. DE-HEAT will assess the efficiency of marine ESW in stimulating oceanic CO2 uptake by increasing alkalinity and evaluate its environmental impact, by applying an innovative fully integrated approach combining extensive field campaigns with state-of-the-art numerical models.