Ocean warming is increasing the frequency, extent, and severity of tropical-coral bleaching and mortality. During 2014-2017, marine heatwaves caused the Third Global Coral Bleaching Event. We analyze data from 15,066 reef surveys globally during 2014-2017. Across all surveyed reefs, 80% and 35% experienced moderate or greater (affecting >10% of corals) bleaching and mortality, respectively. We assess the global extent of coral bleaching and mortality by applying bleaching response curves calibrated from surveyed reefs to predict bleaching globally, based on comprehensive remote-sensing of heat stress. These models predict that 51% and 15% of the world's coral reefs suffered moderate or greater bleaching and mortality, respectively, during one or multiple years, surpassing damage from any prior global coral bleaching event. Our findings demonstrate that the impacts of ocean warming on coral reefs are accelerating, with the near certainty that ongoing warming will cause large-scale, possibly irreversible, degradation of these essential ecosystems. With heat stress levels during this event surpassing those observed previously, the National Oceanic and Atmospheric Administration developed more extreme Bleaching Alert levels that are now being used during the ongoing Fourth Global Coral Bleaching Event.

We must integrate effective protection with scalable restoration to ensure resilient coastal ecosystems. We identify five challenges, including unequal ecosystem coverage, spatial protections that are weak or centered offshore, compartmentalized restoration efforts, and policies that are not fit for purpose, and propose actionable solutions for scaling effective marine conservation. Emphasizing underserved habitats like kelp forests and seagrasses, we call for integrated, equitable, and community-supported strategies that align with global agendas and promote future coastal ecosystems.

Global agreements under the Convention on Biological Diversity (CBD) and the UN Framework Convention on Climate Change (UNFCCC) call for integrated action on biodiversity loss and climate change. Yet national implementation remains poorly understood, even for ecosystems highly vulnerable to warming, such as tropical coral reefs. Bleaching-level heat stress has affected over 85% of global reefs and likely impacted at least 97 of 101 reef-holding countries (Spady et al., 2025a), jeopardizing the benefits reefs provide for people and nature. We assessed how the 25 countries with the largest reef areas (“high-coral countries”) are translating global commitments into national strategies by analyzing National Biodiversity Strategies and Action Plans (NBSAPs) and targets aligned with the Kunming–Montreal Global Biodiversity Framework (KM-GBF), as well as Nationally Determined Contributions (NDCs) and National Adaptation Plans (NAPs) under the Paris Agreement. As of August 2025, 71% of high-coral countries had submitted KM-GBF-aligned biodiversity targets, but none included measurable commitments for coral reefs. Only one country linked climate threats to quantitative Target 3 commitments, and just 8 of 25 referenced marine ecosystem action under Target 8. Under the Paris Agreement, fewer than half (48%) mentioned coral reefs in NDCs, and only three included measurable reef-related commitments; seven countries referenced reefs in NAPs, none with quantitative targets. These findings reveal a major disconnect between global ambition and national action, with coral reefs largely absent from operational planning. We propose three priorities to close this gap: (i) co-develop dedicated national coral reef strategies; (ii) elevate coral reefs within NBSAPs as biodiversity and climate-resilience priorities; and (iii) include measurable coral reef commitments within future NDCs and NAPs. Strengthening policy coherence across biodiversity and climate frameworks is essential to secure climate-resilient coral reefs and the communities that depend on them.

Marine mammals play crucial roles in marine ecosystem function yet are threatened by increasing pressures from anthropogenic activities within marine ecosystems. Area-based Management Tools (ABMT) are key for their conservation and protection, yet their effectiveness is often hindered by lack of resources, technical capacity and political support. Yet, ABMTs are grounded in local, national, regional, and international agreements and policy frameworks including the Kunming-Montreal Global Biodiversity Framework (GBF). To support marine managers, the “Marine Mammals Management Toolkit” was developed and is composed of three core components, including the Self-Assessment Tool (SAT), founded on the Protected Area Management Effectiveness (PAME) framework, and is a multiple-choice tool that enables managers to evaluate the effectiveness of management plans regarding marine mammals through the production of a Management Effectiveness Score (MES). The SAT has been utilised across 24 MPAs in 18 countries. Two case studies are provided on its application. The Stellwagen Bank National Marine Sanctuary (SBNMS) evaluated their existing management plan, and scored an MES value of 7.8 with the Bermuda Marine Mammal Sanctuary (BMMS) scoring 4.7. The results of the SAT enabled the Bermudian Government to make informed decisions in developing a Marine Spatial Plan for the BMMS, and enables SBNMS to set a baseline to track effectiveness over the life-time of SBNMS and respective management plans; guiding local and national policy, as well as enabling Bermuda and the United States of America to contribute to their international commitments.

Ocean warming is increasing the incidence, scale, and severity of global-scale coral bleaching and mortality, culminating in the third global coral bleaching event that occurred during record marine heatwaves of 2014-2017. While local effects of these events have been widely reported, the global implications remain unknown. Analysis of 15,066 reef surveys during 2014-2017 revealed that 80% of surveyed reefs experienced significant coral bleaching and 35% experienced significant coral mortality. The global extent of significant coral bleaching and mortality was assessed by extrapolating results from reef surveys using comprehensive remote-sensing data of regional heat stress. This model predicted that 51% of the world’s coral reefs suffered significant bleaching and 15% significant mortality, surpassing damage from any prior global bleaching event. These observations demonstrate that global warming’s widespread damage to coral reefs is accelerating and underscores the threat anthropogenic climate change poses for the irreversible transformation of these essential ecosystems.

Ocean ecosystems play a key role in maintaining the integrity of our biosphere, but vary widely with respect to their biodiversity attributes, their relationship with the atmosphere and climate change processes, and the ecosystem services that they provide to humans. Coral reefs and ecologically associated coastal ecosystems, such as intertidal mangrove forests and seagrass meadows, are complex systems that are often managed together but are also subject to different governance frameworks. The implementation of the UN Framework Convention on Climate Change’s Paris Agreement and development of global biodiversity goals and targets under the Convention on Biological Diversity offer examples of these governance challenges, but they also offer significant opportunities to maximize biodiversity outcomes while building on increasing support for nature-based solutions to climate change mitigation and adaptation. This whitepaper summarizes the scientific and policy consensus at the oceanclimate nexus, specifically with respect to the role of coral reefs and closely associated tropical coastal ecosystems in climate change processes, and explicitly identifies gaps within key intergovernmental climate and biodiversity policy frameworks that must be addressed to maximize their potential as naturebased solutions during a key decade of conservation action. It concludes with recommendations for national governments and other stakeholders.

Reef fish occupy numerous functional groups and play integral roles in maintaining the health of coral reef ecosystems. However, the management and conservation of these fish groups, and thus coral reefs, are hindered by a paucity of information regarding their spatial distribution patterns and the environmental drivers behind these patterns in the Philippines. Therefore, this study quantified the spatial abundance patterns of selected functional fish groups around two coastal bays in the Philippines, and determined which factors influenced these patterns on both small, localised and larger regional scales. A modified Reef Check methodology was utilised to determine the abundance of fish groups and the substrate composition for 15 coral reefs situated in five delineated regions. The abundance of herbivorous, coralivorous, and top predatory fishes were highly variable, both within and between reefs. Significant differences in fish group abundance were found at the reef, but not at the regional level. Commercially important fish groups (Scaridae, Lutjanidae, and Epinephelinae) were dominated by small size classes (less than 20 cm total length). Sites were also found to be variable in their substrate composition and subsistence fishing effort. Generalised Linear Mixed Models highlighted that localised influences of fishing and hard coral cover, rather than larger-scale regional influences, were the most influential on the abundance patterns of herbivorous, coralivorous and top predatory fish groups. This may suggest that the current management approach of localised small-scale marine protected areas (MPAs) may benefit some of these fish communities. However, top predatory fish likely display far-reaching movement patterns that are not encompassed by these small MPAs, and further management efforts are recommended.

Aim Mega-diverse coral reef ecosystems are declining globally, necessitating conservation prioritizations to protect biodiversity and ecosystem services of sites with high functional integrity to promote persistence. In practice however, the design of marine-protected area (MPA) systems often relies on broad classifications of habitat class and size, making the tacit assumption that all reefs are of comparable condition. We explored the impact of this assumption through a novel, pragmatic approach for incorporating variability in coral cover in a large-scale regional spatial prioritization plan. Location The Coral Triangle. Methods We developed a spatially explicit predictive model of hard coral cover based on freely available macro-ecological data to generate a complete regional map of coral cover as a proxy for reef condition. We then incorporate this information in spatial conservation prioritization software Marxan to design an MPA system that meets specific conservation objectives. Results We discover prioritizations using area-based representation of reef habitat alone may overestimate the conservation benefit, defined as the amount of hard coral cover protected, by up to 64%. We find substantial differences in conservation priorities and an overall increase in habitat quality metrics when accounting for predicted coral cover. Main conclusions This study shows that including habitat condition in a large-scale marine spatial prioritization is feasible within time and resource constraints, and calls for increased implementation, and evaluation, of such ecologically relevant planning approaches to enhance potential conservation effectiveness.