Predicting marsh vulnerability to sea-level rise using Holocene relative sea-level data

• Main Authors: Horton, Benjamin Peter, Shennan, Ian, Bradley, Sarah L., Cahill, Niamh, Kirwan, Matthew, Kopp, Robert E., Shaw, Timothy Adam
• Other Authors: Asian School of the Environment
• Format: Article
• Language: English
• Published: 2018
• Subjects: Sea Level Rise; DRNTU::Science::Geology; Holocene
• Online Access: https://hdl.handle.net/10356/88399; http://hdl.handle.net/10220/45758
• Institution: Nanyang Technological University

Tidal marshes rank among Earth’s vulnerable ecosystems, which will retreat if future rates of relative sea-level rise (RSLR) exceed marshes’ ability to accrete vertically. Here, we assess the limits to marsh vulnerability by analyzing >780 Holocene reconstructions of tidal marsh evolution in Great Britain. These reconstructions include both transgressive (tidal marsh retreat) and regressive (tidal marsh expansion) contacts. The probability of a marsh retreat was conditional upon Holocene rates of RSLR, which varied between −7.7 and 15.2 mm/yr. Holocene records indicate that marshes are nine times more likely to retreat than expand when RSLR rates are ≥7.1 mm/yr. Coupling estimated probabilities of marsh retreat with projections of future RSLR suggests a major risk of tidal marsh loss in the twenty-first century. All of Great Britain has a >80% probability of a marsh retreat under Representative Concentration Pathway (RCP) 8.5 by 2100, with areas of southern and eastern England achieving this probability by 2040.