A geological perspective on sea-level rise and its impacts along the US mid-Atlantic coast

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 (similar to 1.7 +/- 0.2 mm/yr since 1880 CE) and subsidence from glacio-isostatic adjustment (similar to 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).