Are Near-Coastal Sea Levels Accelerating Faster Than Global during the Satellite Altimetry Era?

Abstract

Impact and risk assessments in coastal areas are informed by current and future sea level rise and acceleration, which demands a better understanding of drivers for regional sea level acceleration. In our study, we analyze the near-coastal sea level acceleration compared with global values during satellite altimetry (1993–2020) and discuss the potential drivers of regional sea level acceleration. We estimate regional sea level acceleration using high-resolution satellite altimetry sea surface height anomalies. Our study reveals a wide range of regional acceleration estimates, varying from −1.2 to 1.2 mm·yr−2, which can be up to 20 times larger or smaller than the global mean sea level acceleration of 0.07 mm·yr−2. Notably, sea level acceleration near the global coastline is calculated at 0.10 ± 0.03 mm·yr−2, exceeding the global mean sea level acceleration by 40%. Regional patterns of sea level acceleration are in good agreement with acceleration patterns calculated from the steric sea level. However, the magnitude of acceleration is only partially explained by the changes in steric sea level, with increasing contributions from the non-steric component.