Title | Relative sea-level change in South Florida during the past ~5000 years |
Publication Type | Journal Article |
Year of Publication | 2022 |
Authors | Khan, NS, Ashe, E, Moyer, RP, Kemp, AC, Engelhart, SE, Brain, MJ, Toth, LT, Chappel, A, Christie, M, Kopp, RE, Horton, BP |
Journal | Global and Planetary Change |
Volume | 216 |
Pagination | 103902 |
Date Published | 09/2022 |
ISSN | 0921-8181 |
Keywords | Holocene, mangrove, Proxy reconstruction, Reproducibility, sea level |
Abstract | A paucity of detailed relative sea-level (RSL) reconstructions from low latitudes hinders efforts to understand the global, regional, and local processes that cause RSL change. We reconstruct RSL change during the past ~5 ka using cores of mangrove peat at two sites (Snipe Key and Swan Key) in the Florida Keys. Remote sensing and field surveys established the relationship between peat-forming mangroves and tidal elevation in South Florida. Core chronologies are developed from age-depth models applied to 72 radiocarbon dates (39 mangrove wood macrofossils and 33 fine-fraction bulk peat). RSL rose 3.7 m at Snipe Key and 5.0 m at Swan Key in the past 5 ka, with both sites recording the fastest century-scale rate of RSL rise since ~1900 CE (~2.1 mm/a). We demonstrate that it is feasible to produce near-continuous reconstructions of RSL from mangrove peat in regions with a microtidal regime and accommodation space created by millennial-scale RSL rise. Decomposition of RSL trends from a network of reconstructions across South Florida using a spatio-temporal model suggests that Snipe Key was representative of regional RSL trends, but Swan Key was influenced by an additional local-scale process acting over at least the past five millennia. Geotechnical analysis of modern and buried mangrove peat indicates that sediment compaction is not the local-scale process responsible for the exaggerated RSL rise at Swan Key. The substantial difference in RSL between two nearby sites highlights the critical need for within-region replication of RSL reconstructions to avoid misattribution of sea-level trends, which could also have implications for geophysical modeling studies using RSL data for model tuning and validation. |
URL | https://www.sciencedirect.com/science/article/pii/S0921818122001692 |
DOI | 10.1016/j.gloplacha.2022.103902 |