Paper No. 9
Presentation Time: 10:00 AM
Global, Regional, and Local Sea Level Rise on the U.S. Atlantic and Gulf Seaboard: Atlantic City as the New Atlantis?
Rising sea level threatens coastal communities, yet this threat is often exaggerated. Sea-level rise is affected by global processes, including ice melting and thermal expansion, regional subsidence, and local compaction. We show that the maximum global rate of sea-level rise from 5000 ka to 1850 A.D. was 0.75±0.25 mm/y. Recent studies have documented that the 20th century global sea level rise was 1.8±0.3 mm/y, but has accelerated over the past 15 yr and is rising today at 3.3±0.4 mm/y. Thus, we attribute <30% of the modern global rise to natural causes. The IPCC best estimate, that global sea level will rise 40 cm by 2100, is too low: we are currently tracking a minimum global rise of 80 cm by 2100. The maximum global rise is poorly constrained but maximum rates observed in the geological record are 20-40 mm/yr. We suggest a maximum global rise of <2 m by 2100 A.D. (best est. 1.2±0.4 m). Regional and local subsidence, ranging from 1-2 mm/yr along the U.S. east coast to over a 10 mm/yr in southern Louisiana, exacerbate the global rise. Regional subsidence is caused by isostatic adjustments to removal of the Laurentide ice sheet and/or sediment loading; local subsidence is typically caused by groundwater withdrawal and compaction. Together, these three effects will cause a minimum of ~1 m of rise along the U.S. Atlantic and Gulf seaboard resulting in loss of land (1-3% of the U.S. east coast), loss of marshland, and higher beach erosion. The effect of global temperature rise on storm intensity and frequency are not clear, but sea-level rise will exacerbate flooding during storms. By 2100 much of the New Jersey barrier islands will be impacted causing flooding of bays, streets, and Newark and Atlantic City Municipal Airports during peak storm surges.