The COVID-19 pandemic is the first serious test of how science can inform decision-making in the face of an immediate global threat, yielding important lessons on how science, society and policy interact. The global societal and economic impact of COVID-19 has shown that we need to assess, plan and prepare for potential future changes. These insights are particularly important for the ocean science community because of the global connectivity of the ocean and its crucial role in the Earth's climate system and in supporting all life on Earth. With climate change already impacting society and ecosystems, implementing mitigation measures to avoid and reduce emissions of greenhouses gases is an immediate priority (IPCC, 2021). Irreversible changes are already underway in the oceans and their impacts over the coming decades will continue to affect human communities, requiring societal responses and adaptation across multiple scales (IPCC, 2019, 2021).

The importance of the ocean in the Earth's climate system, influencing weather patterns and affecting sea level, is now recognized by governments and increasingly so by the public. Less well-appreciated is the central role of the ocean in maintaining ecosystems and biodiversity and in supporting human systems. Approximately 680 million people live in low-lying coastal zones, and ocean and coastal economies support millions of people globally (Ebarvia, 2016; IPCC, 2019). The global economy associated with our coasts and ocean (the “Blue Economy”) is estimated to have an asset base of over US$24 trillion (24 ×10¹²) and generates at least US$2.5 trillion each year from the combination of fishing and aquaculture, shipping, tourism, and other activities (OECD, 2016). Nevertheless, marine systems across the planet are being altered because of climate change and human activity with impacts at local to global scales (e.g., Allison and Bassett, 2015; He and Silliman, 2019; IPCC, 2019; UN, 2021). These changes are unprecedented, threatening the capacity of the ocean to maintain crucial services to the planet and human communities (ecosystem services), including those that provide (e.g., food, water, and economic security), regulate (e.g., climate), support (e.g., nutrient cycling) and are cultural in their nature (e.g., traditional or recreational use) (IPCC, 2019; Sala et al., 2021) and so are increasing the potential for societal conflict.

The challenge is urgent. There is an immediate requirement to go beyond calls for action to deal with aspects of the impacts of climate change and human activities on the ocean (IPCC, 2019; UNESCO-IOC, 2021). An Action Plan for the Ocean is needed that develops a comprehensive global understanding of and plan for dealing with multiple ocean risks, that is flexible and adaptive as knowledge expands and new threats arise. The urgency of the challenge requires an internationally coordinated effort that draws on existing global research capacity and networks; a key opportunity presented by the UN Decade of Ocean Science for Sustainable Development 2021-2030 (UNESCO-IOC, 2021) that must not be missed if we are to minimize change in ocean systems and impacts on the services they provide to society.

An awareness of risk is necessary to prepare responses to an uncertain future. The COVID-19 pandemic provides a timely insight into what can happen if there is not full awareness of risk, or if available information on risk is not acted upon and appropriate planning put in place. Over almost two decades, national and international risk assessment activities have made it clear that the likelihood of a global pandemic occurring and causing massive international, social and economic disruption was very high (e.g., Ross et al., 2015; WHO, 2017). Yet, when the COVID-19 pandemic surged across the world, the response was (and continues to be) variable (Dewi et al., 2020), being slow, poorly coordinated or even conflicting at both national and international levels in many regions. As the pandemic continues, insights into what went wrong, what went right and what should happen next are beginning to emerge (Dewi et al., 2020; Weible et al., 2020). These insights are relevant to the ocean science community because the impacts of major changes in the state of the ocean will likely far exceed the global social and economic consequences of the COVID-19 pandemic.

The financial cost of the COVID-19 pandemic is uncertain, with early projections suggesting trillions to 10 s of trillions of US dollars over 5 years (WEF, 2020). Losses associated with climate change impacts on the ocean are likely to be at least of similar magnitude and will continue to develop for decades. Without mitigation and adaptation measures, sea level rise scenarios project annual losses of 0.3–9.3% of global GDP by 2100 (IPCC, 2019; equivalent to ~US$0.25 to US$7.88 trillion per year based on 2020 GDP, World Bank, 2021), while losses from declines in ocean health and services by 2050 are projected to be US$428 billion per year, and by 2100 US$1.979 trillion per year. Under high emission scenarios, global fisheries revenue is projected to decline by over 10% over the next three decades, resulting in an annual reduction of between US$6 and US$15 billion (Lam et al., 2016). However, the recent IPCC (2019) report on the state of the ocean demonstrates the general lack of knowledge of the cost of many of the potential impacts at different scales.

The risks to societies and economies arising from natural or human-driven changes in the ocean have similarly been recognized by the scientific community and highlighted to governments and the public numerous times (e.g., IPCC, 2019, 2021; UN, 2021). Although general societal awareness of these risks is increasing (e.g., ORRAA, 2021), there is a need to ensure that the risks to the ocean, and associated human well-being, are fully understood and lead to appropriate planning and action to reduce or manage those risks. To support this, decision-makers need the relevant information and tools to make the necessary decisions at the appropriate time (Evans et al., 2019).

Building the information systems and tools for facilitating understanding and timely and appropriate decision making requires a coordinated transdisciplinary global effort linking natural, social and economic sciences (Rosa et al., 2017; Laffoley et al., 2020; Norstrom et al., 2020; Pendleton et al., 2020; UNESCO-IOC, 2021). Over the last decade, a number of programmes and projects have driven international efforts to develop the integration of human systems in global ocean ecosystem science, including the Integrated Marine Biosphere Research (IMBeR) project (Hofmann et al., 2015) to which the authors contribute.

We call on the ocean science community to unite to develop an Action Plan for the Ocean that underpins sustainable development and ensures that adaptive responses to global, regional and local risks are agile, well-coordinated, effective and equitable. We suggest that this is the grand challenge for ocean science for the 21st century. To help meet this challenge, the UN Decade of Ocean Science for Sustainable Development 2021-2030 (UNESCO-IOC, 2021) provides an opportunity to build global support systems for informing decision making on the critical time scales of the coming years and decades.

We propose a three-component process to develop an Action Plan for the Ocean (Figure 1): (1) assess and rank risks, (2) identify options for action, and (3) develop action plans for adaptation at local, regional and global scales to respond to future change. This process needs to be continuously updated as new information becomes available and understanding improves.

The World Health Organization (WHO) was able to monitor and communicate the development of COVID-19 so that universal information and warnings were provided for developing responses in a rapidly changing environment. Currently there are multiple international and national bodies and independent organizations generating assessments of the state of the ocean and the likely impacts of future change. Governance and management in the world's ocean ecosystems are based on national activities and international agreements that vary in scope and scale and in which there are many gaps and conflicting aims (see examples, IPBES, 2019; IPCC, 2019; UN, 2021). This collectively results in varying effectiveness and resourcing of activities across the globe and often results in competition for resources between initiatives.

A key lesson from the COVID-19 pandemic is that a patchwork of ad-hoc activities will not provide the scientific or advisory basis required for developing and implementing appropriate response to the changes expected and their impacts on natural and human systems. Without a coherent approach to the development of plans for action, marine crises will mirror the worst aspects of the response to the pandemic: uncertain, ineffective and delayed. The COVID-19 pandemic is a wake-up call for the ocean science community.

The urgency of the challenge is clear. Already sea level, ocean temperature and acidification of the ocean are increasing, and changes to ocean ecosystems are occurring (IPCC, 2019; UN, 2021). Over the near future ocean stratification will strengthen, sea ice will reduce, oxygen will decline, and the frequency of extreme events will increase, with projected declines in net primary productivity, global biomass of marine animal communities and fisheries catch potential, with the poorest nations experiencing the greatest projected losses (e.g., Lam et al., 2016; Lotze et al., 2017; IPCC, 2019; Boyce et al., 2020). Many of these changes are irreversible even with the most ambitious implementation of mitigation measures—adaptation will therefore be crucial. Systematically improving understanding of the risks, including estimates of the potential costs of future change in the ocean through multiple processes (Narita et al., 2020), will be essential in communicating the importance of developing and implementing an action plan.

For more than two decades there have been strongly justified claims that action is required, but without a coherent global plan such calls will continue to waste resources and time in a fragmented effort. COVID-19 has highlighted to the public and governments the importance of understanding risks and the need to prepare at national and international levels and has demonstrated the crucial role science can play as part of that process. The Action Plan for the Ocean we propose requires coordinated international development and generation of new approaches to assessing risk and the pre-emptive provision of adaptation options for decision makers to respond to future change. New organizational structures are not required, instead effort is needed to bring together existing initiatives and bodies with free and open sharing of datasets, information, and assessment, in a trusted format. This will require engagement with a wide range of ocean science and societal stakeholders in the development, planning, support and implementation of the action plan and to ensure it becomes an embedded long-term process in ocean science and management. IMBeR aims to develop the approach and will scope opportunities to elaborate the concept and present plans at a range of forthcoming international scientific and ocean-policy meetings. The UN Decade of Ocean Science for Sustainable Development can provide a platform for the coordination required, acknowledging and drawing on the strengths and resources of existing research networks and communities that in some cases have taken decades to develop and evolve. Such a coordinated effort can be nimble to new challenges and operate with the willing parties as soon as possible. Without such a response, the multiple effects of ocean change will make the disparate response to the COVID-19 pandemic look relatively successful.

EM led the development of the manuscript. All authors contributed to the ideas and the text and approved the submitted version.

This work was supported through the Integrated Marine Biosphere Research Project (IMBeR) which was supported by the Scientific Committee on Oceanic Research (SCOR) and Future Earth. This publication resulted in part from support from the U.S. National Science Foundation (Grant OCE-1840868) to the Scientific Committee on Oceanic Research (SCOR). EM and publication were also supported through the Ecosystems Programme of the British Antarctic Survey, NERC.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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