Benjamin Horton Torbjörn Törnqvist Erica Ashe Nicole Khan Mark Schuerch Chris Perry Robert E. Kopp Gregory Garner Nicholas Murray Kerrylee Rogers Simon Albert Jeffrey Kelleway Timothy Shaw Colin D. Woodroffe Catherine E. Lovelock Madeline Goddard Lindsay B. Hutley Katya Kovalenko Laura Feher Glenn R. Guntenspergen Neil Saintilan 2023 <p><span>Several coastal ecosystems—most notably mangroves and tidal marshes—exhibit biogenic feedbacks that are facilitating adjustment to relative sea-level rise (RSLR), including the sequestration of carbon and the trapping of mineral sediment</span>^{<a id="ref-link-section-d6940227e925" title="Morris, J. T. et al. Contributions of organic and inorganic matter to sediment volume and accretion in tidal wetlands at steady state. Earths Future 4, 110–121 (2016)." href="https://www.nature.com/articles/s41586-023-06448-z#ref-CR1" data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 1" data-mce-href="https://www.nature.com/articles/s41586-023-06448-z#ref-CR1">1</a>}<span>. The stability of reef-top habitats under RSLR is similarly linked to reef-derived sediment accumulation and the vertical accretion of protective coral reefs</span>^{<a id="ref-link-section-d6940227e929" title="Perry, C. T. et al. Implications of reef ecosystem change for the stability and maintenance of coral reef islands. Global Change Biol. 17, 3679–3696 (2011)." href="https://www.nature.com/articles/s41586-023-06448-z#ref-CR2" data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 2" data-mce-href="https://www.nature.com/articles/s41586-023-06448-z#ref-CR2">2</a>}<span>. The persistence of these ecosystems under high rates of RSLR is contested</span>^{<a id="ref-link-section-d6940227e933" title="Kirwan, M. L., Temmerman, S., Skeehan, E. E., Guntenspergen, G. R. &amp; Fagherazzi, S. Overestimation of marsh vulnerability to sea level rise. Nat. Clim. Change 6, 253–260 (2016)." href="https://www.nature.com/articles/s41586-023-06448-z#ref-CR3" data-track="click" data-track-action="reference anchor" data-track-label="link" data-test="citation-ref" aria-label="Reference 3" data-mce-href="https://www.nature.com/articles/s41586-023-06448-z#ref-CR3">3</a>}<span>. Here we show that the probability of vertical adjustment to RSLR inferred from palaeo-stratigraphic observations aligns with contemporary in situ survey measurements. A deficit between tidal marsh and mangrove adjustment and RSLR is likely at 4 mm yr</span>⁻¹<span>&nbsp;and highly likely at 7 mm yr</span>⁻¹<span>&nbsp;of RSLR. As rates of RSLR exceed 7 mm yr</span>⁻¹<span>, the probability that reef islands destabilize through increased shoreline erosion and wave over-topping increases. Increased global warming from 1.5 °C to 2.0 °C would double the area of mapped tidal marsh exposed to 4 mm yr</span>⁻¹<span>&nbsp;of RSLR by between 2080 and 2100. With 3 °C of warming, nearly all the world’s mangrove forests and coral reef islands and almost 40% of mapped tidal marshes are estimated to be exposed to RSLR of at least 7 mm yr</span>⁻¹<span>. Meeting the Paris agreement targets would minimize disruption to coastal ecosystems.</span></p> application/pdf 10.1038/s41586-023-06448-z en Nature Widespread retreat of coastal habitat is likely at warming levels above 1.5 °C article