Subpolar North Atlantic heat flux drives projected U.S. East Coast sea-level trend in a climate model

Abstract Dynamic sea level along the United States (U.S.) East Coast has risen for decades and is projected to continue rising throughout the 21st century. The mechanisms by which ocean surface forcing drives this rise are not fully understood. Here, we use an adjoint sensitivity-based method from the Estimating the Circulation and Climate of the Ocean (ECCO) project to attribute sea-level change to ocean forcings. By convolving ocean forcings from a Coupled Model Intercomparison Project Phase 6 (CMIP6) model with ECCO adjoint sensitivities, we reconstructed the climate-model sea-level variations along the U.S. East Coast for 2000–2100, using Nantucket, Massachusetts, and Charleston, South Carolina, as proxy locations for the U.S. Northeast and Southeast Coasts. Subpolar North Atlantic surface heat flux is the key driver of the long-term trend, while wind stress dominates interannual-to-decadal variability. Both the time-mean increase and linear trend in heat flux are important for U.S. East Coast sea-level rise.