A geological perspective on sea‐level rise and its impacts along the U.S. mid‐Atlantic coast

Abstract

We evaluate paleo-, historical, and future sea-level rise along the U.S. mid-Atlantic coast.The rate of relative sea-level rise in New Jersey decreased from 3.5 ± 1.0 mm/yr at 7.5-6.5 ka, to 2.2 ± 0.8 mm/yr at 5.5-4.5 ka to a minimum of 0.9 ± 0.4 mm/yr at 3.3-2.3 ka. Relative sea level rose at a rate of 1.6 ± 0.1 mm/yr from 2.2 to 1.2 ka (750 Common Era [CE]) and 1.4 ± 0.1 mm/yr from 800 to 1800 CE. Geological and tide-gauge data show that sea-level rise was more rapid throughout the region since the Industrial Revolution (19th century = 2.7 ± 0.4 mm/yr; 20th century = 3.8 ± 0.2 mm/yr). There is a 95% probability that the 20th century rate of sea-level rise was faster than it was in any century in the last 4.3 kyr. These records reflect global rise (∼1.7 ± 0.2 mm/yr since 1880 CE) and subsidence from glacio-isostatic adjustment (∼1.3 ± 0.4 mm/yr) at bedrock locations (e.g., New York City). At coastal plain locations, the rate of rise is 0.3-1.3 mm/yr higher due to groundwater withdrawal and compaction. We construct 21st century relative sea-level rise scenarios including global, regional, and local processes. We project a 22 cm rise at bedrock locations by 2030 (central scenario; low-and high-end scenarios range of 16-38 cm), 40 cm by 2050 (range 28-65 cm), and 96 cm by 2100 (range 66-168 cm), with coastal plain locations having higher rises (3, 5-6, and 10-12 cm higher, respectively). By 2050 CE in the central scenario, a storm with a 10 year recurrence interval will exceed all historic storms at Atlantic City.Summary An analysis of geological and historical sea-level records shows a significant rate of increase in sea-level rise since the nineteenth century. In New Jersey, it is extremely likely that sea-level rise in the twentieth century was faster than during any other century in the last 4.3 thousand years. Accounting for regional and local factors, the authors project sea-level rise in the mid-Atlantic U.S. most likely about 38-42 ′′ (96-106 cm) over the twentieth century, but possibly as high as 66-71 ′′ (168-180 cm).

Relative sea-level trends in New York City during the past 1500 years

“…Since this minimum the rate of RSL rise increased continuously to attain a current rate of 2.98 mm/yr (2.13-3.84 mm/yr; 95% credible interval), which is the fastest rate in the last ~1500 years and in agreement with the average rate measured in New York Harbor from 1900 CE to 2012 CE (2.7-3.3 mm/yr; Kopp, 2013). (Figures 2A and 7C; Kopp, 2013). This instrumental rate of RSL rise exceeds the long-term (~4000 years before present to 1900 CE) average estimated from compilations of RSL reconstructions from the Hudson River (1.2 ± 0.1 mm/yr) and Long Island (1.0 ± 0.3 mm/yr) regions that are adjacent to New York City (Engelhart and Horton, 2012;Engelhart et al, 2011).…”

“…During the 21 st century New York City will experience RSL rise greater and faster than the global average (e.g., Horton et al, 2015;Miller et al, 2013;Kopp et al, 2014) because of contributions from ongoing glacio-isostatic adjustment (GIA; e.g., Peltier, 2004;Davis and Mitrovica, 1996), changing patterns of ocean circulation (e.g. Yin et al, 2009;Levermann et al, and plants are preserved (e.g., Kemp et al, 2013a;Gehrels et al, 2005;Donnelly et al, 2004;Kemp et al, 2015).…”

Coastal flooding risk associated to tropical cyclones in a changing climate. Application to Port of Spain (Trinidad and Tobago)

“…However, sea level is not rising at the same rate 20 everywhere due to different ocean and land mechanisms (Yin et al, 2009, Mitrovica et al, 2011, Farrell and Clark, 1976, Miller et al, 2013. Consequently the regional variability and local effects are to be accounted for in impact studies.…”

Increased threat of tropical cyclones and coastal flooding to New York City during the anthropogenic era

“…This risk is amplified in NYC, where the rate of RSLR is greater than the global average due to contributions from regional-scale processes such as glacio-isostatic adjustment (GIA) (23)(24)(25). Regardless of uncertainty about the frequency, magnitudes, or tracks of future TCs, risk of coastal inundation for this region will increase as RSLR accelerates.…”