Ocean circulation and climate effects on US East Coast sea-level trends since 1900
Abstract
Much of the global coastline is experiencing relative sea-level (RSL) rise, which can negatively impact the built and natural environment. The US East Coast is especially vulnerable, with observations showing faster-than-global-average rates of RSL rise since ~1900. However, the relative roles of different geological processes and climate dynamics in driving the observed RSL rates in this region are not fully understood, posing a challenge to future projections of regional RSL change. We apply Bayesian data analysis to estimate contributions from different processes to large-scale regional RSL trends on the US East Coast during the past century. Our framework synergistically incorporates data and associated uncertainties from observations, the proxy record, and geophysical models to constrain glacial isostatic adjustment (GIA) and mass redistribution contributions to coastal RSL trends. Our results corroborate past studies arguing that regional vertical land motion due to GIA is the main driver of alongshore variation in recent RSL trends. We also find that 20th-century redistribution of water and ice makes important contributions to the spatial structure, causing faster RSL rise along the southern shore. We interpret residual regional RSL trends unaccounted for by GIA and contemporary mass distribution in terms of sterodynamic sea level, the sum of global-mean thermosteric sea level plus ocean dynamic sea level. Using standard indices relating coastal RSL to ocean currents, we find that different input data, particularly regarding GIA, lead to qualitatively different estimates of how ocean circulation may have changed in the past century. Our results suggest limits in the use of coastal RSL data for inferring ocean circulation and highlight the importance of understanding solid Earth geophysics - particularly at the coast - to support projections of future RSL change.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.G52A..04H