Rafael Jan Pablo Schmitt , Philip S. J. Minderhoud 

450 million people live on river deltas and thus on land that is precariously low above the sea level and sinking because of human activities and natural processes. Although global debates around coastal risk typically focus on sea level rise, it is sinking lands and rising seas that together endanger lives and livelihoods in river deltas. However, the ability to quantify and address those risks in an integrated manner remains limited. Herein, we identify four priority areas where a lack of data, models, and knowledge is limiting sustainable delta management, namely (1) developing practical models for delta-scale processes and nature-based solutions, (2) coupling models for basin and delta processes, (3) closing knowledge disparities between river deltas, and (4) integrating deltas in assessments of global change and vice versa. Addressing those challenges through global scientific effort is instrumental to identify local-to-global levers to design adaptation and mitigation measures for resilient river deltas.