Attribution of interannual-to-centennial sea-level changes in climate models

Dynamic sea level along the United States (U.S.) East Coast has risen in recent decades and is projected to continue rising throughout the 21st century, according to most climate models from the Coupled Model Intercomparison Project Phase 6 (CMIP6). However, the mechanisms by which ocean surface forcing drives this rise remain unclear. Understanding these processes is critical for improving sea-level projections. The adjoint sensitivity-based attribution method from the Estimating the Circulation and Climate of the Ocean (ECCO) project provides a means to establish causal relationships between sea level and ocean forcings. Here, we demonstrate that by convolving ocean forcings from a CMIP6 model with ECCO adjoint sensitivities of sea level to these forcings, we can reconstruct sea-level variations along the U.S. East Coast from 2000 to 2100 in the CMPI6 model. We identify subpolar North Atlantic surface heat flux as the key driver of the long-term trend, while wind stress dominates interannual-to-decadal variability.