IMIS

Tidal marshes provide habitat for juvenile fish, birds, and other wildlife; defend coastlines against storms; and are a major global carbon sink. However, relative sea-level rise (RSLR) threatens them with drowning. Marshes continually build elevation by accreting sediment, but whether riverine sediment supplies are adequate to support accretion that keeps pace with RSLR has remained uncertain. On page 1191 of this issue, Ensign et al. (1) show that even in a best-case scenario, when all riverine sediment is deposited on marshes in the receiving estuaries across the United States, existing supplies are generally insufficient for accretion to keep pace with RSLR. This finding underscores the need for creative coastal planning in a time of sediment austerity that recognizes that change is inevitable and capitalizes on natural sediment redistribution processes that will prolong marsh persistence.