Common Era Sea-level Budgets along the U.S. Atlantic Coast

TitleCommon Era Sea-level Budgets along the U.S. Atlantic Coast
Publication TypeConference Paper
Year of Publication2020
AuthorsWalker JS, Kopp RE, Shaw T, Cahill N, Khan N, Barber DC, Brain M, Clear JL, Corbett DR, Horton BP
Conference NameAmerican Geophysical Union Fall Meeting
Date Published12/2020
Conference LocationOnline
Abstract

A sea-level budget improves understanding of driving processes of sea-level change through time and the relative contributions of these processes. However, most sea-level budget assessments are focused on global-mean sea level and are limited to the 20th and 21st centuries. For the first time we estimate the sea-level budget on centennial to millennial timescales of the Common Era (last 2000 years). We focus our analysis on the U.S. Atlantic coast to better understand the temporal evolution and variability of driving processes that have determined sea-level changes in the past and present, and which will shape such changes in the future. A thorough understanding of these changes is needed for regional to local planning and response to sea-level rise.

We estimate site-specific sea-level budgets over the Common Era at six sites on the U.S. Atlantic coast. With an updated global database of instrumental and proxy sea-level records coupled with a spatiotemporal empirical hierarchical model, we use the unique spatial scales of driving processes to separate relative sea-level records into global, regional, and local-scale components. We find that each budget is dominated by regional-scale, temporally-linear processes driven by glacial isostatic adjustment through the Common Era. This signal exhibits a spatial gradient, with fastest rates of rise in southern New Jersey (1.6 ± 0.02 mm yr-1). Non-linear regional and local-scale processes, such as ocean/atmosphere dynamics and groundwater withdrawal, are of smaller magnitude and exhibit both temporal and spatial variability, with a contribution between -0.3 and 0.4 mm yr-1. The most significant change to the budgets is the increasing influence of the global signal due to ice melt and thermal expansion since 1800 CE, which reaches a 20th century rate of 1.3 ± 0.1 mm yr-1.