The Role of Marine Biodiversity in Enhancing Resilience to Climate Change and Ocean Acidification

Marine biodiversity is an emerging essential constituent of ecosystem resilience against synergistic anthropogenic impacts from climate change and ocean acidification (OA). This review provides a synthesis of current understanding and future predictions about how biological diversity mitigates marine communities against disruption from thermal extremes, disequilibrium in carbonate chemistry, and systemic food web instability. Since pre-industrial times, the surface ocean pH has fallen by roughly 0.1 units from 8.2 to 8.1, the equivalent of a 26% increase in hydrogen-ion concentration, and under high-emission scenarios, a further reduction of 0.3-0.4 pH units is predicted by 2100. Mean sea surface temperatures continue to climb at historically unmatched rates, impacting calcifying organisms, reef engineers, and benthic assemblage structure. Evidence from global meta-analyses and regional field studies across coral reefs, temperate coastal communities, and open ocean settings is discussed. Species richness, functional diversity, and genetic variability are considered in terms of their contribution to resistance and resilience. The contribution of MPAs to resilience building in the context of climate change is also discussed; evidence suggests MPAs recover at rates 40-65% higher than unprotected areas. Several policy tools, including the Convention on Biological Diversity Post-2020 Global Biodiversity Framework, BBNJ Treaty, and UNFCCC Paris Agreement, are reviewed as mechanisms that may reduce vulnerability. A comprehensive approach to preserving marine ecosystem services under future climate trajectories, combining conservation of biological diversity, implementation of MPAs, and global mitigation of emissions, will be critical.