Sea-level rise (SLR) is predicted to elevate water depths above coral reefs and to increase coastal wave exposure as ecological degradation limits vertical reef growth, but projections lack data on interactions between local rates of reef growth and sea level rise. Here we calculate the vertical growth potential of more than 200 tropical western Atlantic and Indian Ocean reefs, and compare these against recent and projected rates of SLR under different Representative Concentration Pathway (RCP) scenarios. Although many reefs retain accretion rates close to recent SLR trends, few will have the capacity to track SLR projections under RCP4.5 scenarios without sustained ecological recovery, and under RCP8.5 scenarios most reefs are predicted to experience mean water depth increases of more than 0.5 m by 2100. Coral cover strongly predicts reef capacity to track SLR, but threshold cover levels that will be necessary to prevent submergence are well above those observed on most reefs. Urgent action is thus needed to mitigate climate, sea-level and future ecological changes in order to limit the magnitude of future reef submergence.
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We thank the many local institutions that supported and facilitated field data collection. Data collection in the tropical western Atlantic was supported through a Leverhulme Trust International Research Network grant (F/00426/G) to C.T.P. and data collection carried out specifically in Mexico was supported through a Royal Society - Newton Advanced Research Fellowship (NA-150360) to L.A.-F. and C.T.P., in Florida and Puerto Rico as part of the National Coral Reef Monitoring Program through NOAA’s Coral Reef Conservation Program and Ocean Acidification Program to D.P.M. and in the eastern Caribbean through a National Geographic Research Grant to R.S.S. Data collection in the Indian Ocean was supported in Kenya and Mozambique through a NERC-ESPA-DFiD: Ecosystem Services for Poverty Alleviation Programme Grant (NE/K01045X/1) to C.T.P., in the Maldives through a NERC Grant (NE/K003143/1) and a Leverhulme Trust Research Fellowship (RF-2015-152) to C.T.P., in the Chagos Archipelago through a DEFRA Darwin Initiative grant (19-027), in the Seychelles through an Australian Research Council grant (DE130101705) and Royal Society grant (RS-UF140691) to N.A.J.G. and in Ningaloo through the BHP-CSIRO Ningaloo Outlook Marine Research Partnership. P.J.M. acknowledges the Australian Research Council and World Bank/GEF CCRES project for funding. Rebecca Fisher (Australian Institute of Marine Science, Western Australia) provided statistical advice.Reviewer information
Nature thanks I. D. Haigh and I. Kuffner for their contribution to the peer review of this work.
Extended data figures and tables
Plots showing mean site level coral carbonate production rate (a) and bioerosion rate (b) data (kg CaCO3 m−2 yr−1) grouped by country or territory within ecoregions for TWA and Indian Ocean sites. Box plots depict the median (horizontal line), box height depicts first and third quartiles, whiskers represent the 95th percentile, and outliers outside the 95th percentile are shown as circles. Country/territory codes are as follows: (1) Florida (n = 36); (2) Puerto Rico (n = 6); (3) Grand Cayman (n = 26); (4) Belize (n = 36); (5) Mexico (n = 64); (6) St. Croix (n = 36); (7) St. Maarten (n = 11); (8) Anguilla (n = 10); (9) Barbuda (n = 20); (10) Antigua (n = 28); (11) St. Lucia and St. Vincent (n = 37); (12) Bequia (n = 12); (13) Mustique (n = 16); (14) Canouan and Tobago Cays (n = 20); (15) Union/PSV and Carriacou (n = 20); (16) Bonaire (n = 62); (17) Mozambique (n = 55); (18) Kenya (n = 29); (19) Seychelles (n = 144); (20) Maldives (n = 25); (21) Chagos (n = 111); (22) Ningaloo (n = 34). n indicates the number of transects per country or territory.
a–d, Calculated RAPmax rates (mm yr−1) before (a, c) and after (b, d) the 2016 bleaching event in the Seychelles and the Maldives. e, Plot shows changes in RAPmax rates at ‘recovered’ (n = 96) and ‘regime-shifted’ reefs37 (n = 72 pre-bleaching, n = 48 post-bleaching) in the Seychelles, and Maldives (n = 35 pre-bleaching, n = 25 post bleaching). Box plots depict the median (horizontal line), box height depicts first and third quartiles, whiskers represent the 95th percentile, and outliers outside the 95th percentile are shown as circles.
Supplementary Table 1 - Field data and accretion. The file contains location data for all sites along with transect level data on measured rates of carbonate production and bioerosion, and resultant reef accretion rates.
Supplementary Table 2 - Recent and projected SLR rates. File contains recent and projected rates of SLR for each study region.
Supplementary Table 3 - Accretion-SLR interactions and projected increases in water depths. File contains data on calculated differences between accretion rates and recent and projected rates of sea level rise under RCP4.5 and 8.5 sea-level rise scenarios.