New Methods to Measure the Real-World Impacts of Ocean Acidification on Marine Species and Ecosystems Will Increase Local Climate Resilience and Adaptation
Steve Widdicombe
Plymouth Marine Laboratory, United Kingdom
“Our new method for directly comparing the hugely varied biological impacts of ocean acidification, seen at different monitoring stations all across the planet, will provide us with the evidence needed to future-proof marine ecosystem management and ensure greater climate resilience for both humans and nature”
Human induced changes to the Earth system directly impact the health of the World’s ocean, its chemistry, its ecological properties and its natural resources, and consequently the provision of ecosystem services to human communities. Through our activities, humans have been releasing ever increasing amounts of CO2 into the atmosphere, and in 2022 we released over 35 billion tonnes of carbon dioxide (CO2) in a single year (Ritchie and Roser, 2020). Over the centuries these emissions have raised the atmospheric concentration of CO2 from 280ppm to over 420ppm, a figure that would have been much higher were it not for the fact that about one-quarter of all the CO2 we have released has subsequently been absorbed by the ocean. As this CO2 has entered the ocean it has reacted with the seawater to form carbonic acid, that has driven a chemical phenomenon called “ocean acidification”. The consequences of the ocean acidification process are a reduction in pH (i.e. increased acidity) and changes in other key chemical elements of the seawater carbonate system. In coastal areas, this acidification is worsened by a number of local processes that also affect carbonate chemistry, such as enhanced upwelling of deep ocean water to the surface, sea ice melt, riverine inputs, pollution and increased temperature. Such are the likely adverse effects for marine species and ecosystems caused by ocean acidification, that it is recognised as one of the nine planetary boundaries that should not be exceeded if Earth’s overall health and well-being is to be preserved (Rockström et al., 2009). In a recent review of those planetary boundaries (Richardson et al., 2023), it was suggested that anthropogenic (human-induced) ocean acidification currently lies at the margin of the safe operating space, and the trend is worsening as anthropogenic CO2 emission continues to rise. If this threat to marine species, ecosystems and biodiversity from ocean acidification is not motivation enough to take action, then purely from an economic perspective the evidence to act is compelling. A recent report (Moore and Fuller, 2020) estimated that the economic damages from ocean acidification at the end of this century would be in the region of US$47 and US$58 for every person on the planet. At our current population level of around 8 billion, that would equate to around US$400 billion.
Clearly, ocean acidification poses a serious and growing threat to marine ecosystems and the human communities that depend on them. Whilst a significant global reduction in CO2 emissions is the primary and most pressing action required to reduce this threat, local targeted actions are also required to combat those other processes that contribute to coastal acidification. In order to best identify, design and target those local actions it is essential that we can locate those places where acidification poses the highest risk and where the biological consequences are most acute. This requires us to be able to measure both the chemical changes associated with ocean acidification and its biological impacts. Whilst methods to measure those chemical changes are now well established (Tilbrook et al., 2019), the more challenging task of quantifying the biological impacts remains, especially from in-situ observations under real-world conditions. And while countries being asked to reduce the impacts of ocean acidification as part of a United Nations’ Sustainable Development Goals (SDG target 14.3) and by Target 8 of the Kunming Montreal Global Biodiversity Framework, this effort has largely been hampered by a lack of agreed methodology and indicators for how these impacts should be observed and compared.
In our work (Widdicombe et al., 2023), we make use of the knowledge gained from nearly two decades of Ocean Acidification research and laboratory experiments, to address this method gap and identify a set of five fundamental biological and ecological traits that are relevant across all marine ecosystems, have a strongly demonstrated link to Ocean Acidification and have implications for ocean health and the provision of ecosystem services with impacts on local marine management strategies and economies. These traits can then act as indicators and, when coupled with carbonate chemistry monitoring, will allow the rate and severity of biological change in response to ocean acidification to be observed and compared across regional and global scales. In addition to ocean acidification, marine ecosystems face a number of simultaneously occurring human induced pressures. Our new approach allows the specific effects of acidification to be appreciated whilst also resolving some of the complex combined effects and ecological interactions that will occur in a multi-stress environment. Last but not least, the approaches described in our paper come full circle to benefit future laboratory experiments by demonstrating how effective biological monitoring in the field can help resolve and identify the underlying mechanisms that drive biological responses to ocean acidification. These mechanisms, and the unifying principles they reveal, can then be tested through a new wave of laboratory-based studies.
Successful application of environmental and ecological indicators is fundamental to the progression of academic understanding and in the successful implementation of action. Traditionally, routine monitoring and observations have underpinned the development of critical scientific understanding of both the marine environment and of the impacts that humans are having on it (Bean et al., 2017). Ultimately, marine environmental in-situ observations are a prerequisite for ecosystem-based management and are essential to ensure that sustainable management targets are met. So our next steps, with financial support from the Velux Foundation to the Intergovernmental Oceanographic Commission of UNESCO, will be to test our indicators of ocean acidification impact using data gathered from different long-term marine observing stations from different parts of the World. Simultaneously, we will be working through the United Nations Decade of Ocean Science for Sustainable Development endorsed programme Ocean Acidification Research for Sustainability (OARS) and with the Global Ocean Acidification Observing Network (GOA-ON), a network of over 1,000 researchers from over 100 countries, to embed these new indicators into existing and emerging ocean acidification observing systems. We will also be reaching out to existing biological monitoring and observing programmes, to help them build on their current activities and to contribute to a broader assessment of ocean acidification and its biological impacts.
Ocean acidification is a serious and growing threat to a variety of marine ecosystems all around the World, and to the well-being of those people who depend on such ecosystems for their livelihoods, their health and for the protection those systems provide against extreme weather events. Tackling the environmental and economic impacts of ocean acidification can only be effective if we can target our actions towards those ecosystems and people who will be most affected. It will also provide greater evidence, should it be needed, of the importance for wide-scale global reductions in CO2 emissions. Our new set of impact indicators will help us to observe and quantify the biological impacts of ocean acidification on species and ecosystems, generating the data needed to increase local climate resilience and adaptation.
Figure 1. Visual summary of the thought piece and winning article.
Photo 1. Members of the Global Ocean Acidification Observing Network’s ‘Biological Working Group’, and authors of the paper, gathered outside the Kristineberg Marine Station, Sweden, during one of their meetings.
References
Ritchie, Hannah, Max Roser, and Pablo Rosado. CO₂ and greenhouse gas emissions. Our world in data, 2020. Ritchie, Hannah, Max Roser, and Pablo Rosado. "CO₂ and greenhouse gas emissions." Our world in data (2020).
Rockström, Johan, Will Steffen, Kevin Noone, Åsa Persson, F. Stuart Chapin, Eric F. Lambin, Timothy M. Lenton et al. A safe operating space for humanity. Nature 461, no. 7263, 2009. pp.472-475.
Richardson, Katherine, Will Steffen, Wolfgang Lucht, Jørgen Bendtsen, Sarah E. Cornell, Jonathan F. Donges, Markus Drüke et al. Earth beyond six of nine planetary boundaries. Science advances 9, no. 37, 2023. eadh2458.
Moore, Christopher, and Jasmine Fuller. Economic impacts of ocean acidification: a meta-analysis. U.S. Environmental Protection Agency, National Center for Environmental Economics, 2020.
Tilbrook, Bronte, Elizabeth B. Jewett, Michael D. DeGrandpre, Jose Martin Hernandez-Ayon, Richard A. Feely, Dwight K. Gledhill, Lina Hansson et al. An enhanced ocean acidification observing network: from people to technology to data synthesis and information exchange. Frontiers in Marine Science 6, 2019. pp.337.
Bean, Tim P., Naomi Greenwood, Rachel Beckett, Lauren Biermann, John P. Bignell, Jan L. Brant, Gordon H. Copp et al. A review of the tools used for marine monitoring in the UK: combining historic and contemporary methods with modeling and socioeconomics to fulfill legislative needs and scientific ambitions. Frontiers in Marine Science 4, 2017. pp.263.
Widdicombe, Steve, Kirsten Isensee, Yuri Artioli, Juan Diego Gaitán-Espitia, Claudine Hauri, Janet A. Newton, Mark Wells, and Sam Dupont. Unifying biological field observations to detect and compare ocean acidification impacts across marine species and ecosystems: what to monitor and why. Ocean Science 19, no. 1, 2023. pp.101-119.
