Projections of global delta land loss from sea‐level rise in the 21st century

River deltas will likely experience significant land loss because of relative sea-level rise (RSLR), but predictions have not been tested against observations. Here, we use global data of RSLR and river sediment supply to build a model of delta response to RSLR for 6,402 deltas, representing 86% of global delta land. We validate this model against delta land area change observations from 1985–2015, and project future land area change for IPCC RSLR scenarios. For 2100, we find widely ranging delta scenarios, from +94 ± 125 (2 s.d.) km² yr⁻¹ for representative concentration pathway (RCP) 2.6 to −1,026 ± 281 km² yr⁻¹ for RCP8.5. River dams, subsidence, and sea-level rise have had a comparable influence on reduced delta growth over the past decades, but if we follow RCP8.5 to 2100, more than 85% of delta land loss will be caused by climate-change driven sea-level rise, resulting in a loss of ∼5% of global delta land.