Past and future sea-level rise along the coast of North Carolina, USA

TL;DR

This study reconstructs and projects sea-level rise along North Carolina's coast, revealing accelerated 20th-century rise and significant future increases under high-emission scenarios, impacting flood risk and coastal planning.

Contribution

It combines geological reconstructions, tide-gauge data, and modeling to provide detailed past and future sea-level rise estimates for North Carolina.

Findings

20th-century RSL rise at Sand Point was the fastest in 2,900 years.

Future RSL at Wilmington is projected to rise by 42-132 cm by 2100 under RCP 8.5.

The 1-in-100 year flood is expected to occur roughly 30 times between 2050-2100 under high emissions.

Abstract

We evaluate relative sea level (RSL) trajectories for North Carolina, USA, in the context of tide-gauge measurements and geological sea-level reconstructions spanning the last $\mathord{\sim}$11,000 years. RSL rise was fastest ($\mathord{\sim}$7 mm/yr) during the early Holocene and slowed over time with the end of the deglaciation. During the pre-Industrial Common Era (i.e., 0--1800 CE), RSL rise ($\mathord{\sim}$0.7 to 1.1 mm/yr) was driven primarily by glacio-isostatic adjustment, though dampened by tectonic uplift along the Cape Fear Arch. Ocean/atmosphere dynamics caused centennial variability of up to $\mathord{\sim}$0.6 mm/yr around the long-term rate. It is extremely likely (probability $P = 0.95$) that 20th century RSL rise at Sand Point, NC, (2.8 $\pm$ 0.5 mm/yr) was faster than during any other century in at least 2,900 years. Projections based on a fusion of process models, statistical models, expert elicitation, and expert assessment indicate that RSL at Wilmington, NC, is very likely ($P = 0.90$) to rise by 42--132 cm between 2000 and 2100 under the high-emissions RCP 8.5 pathway. Under all emission pathways, 21st century RSL rise is very likely ($P > 0.90$) to be faster than during the 20th century. Due to RSL rise, under RCP 8.5, the current `1-in-100 year' flood is expected at Wilmington in $\mathord{\sim}$30 of the 50 years between 2050-2100.