UConn Marine Sciences Associate Professor Samantha Siedlecki co-leads a project to incorporate data on historic and projected ocean conditions to predict the growth of scallops across vast geographic regions and more than a century of time. The project uses a novel tool developed by UConn Ph.D. candidate Halle Berger. Photo by NOAA.
In the coastal waters stretching from Maine to Virginia, Atlantic sea scallops rival lobster as the top shellfish caught in the wild. This delectable mollusk supports one of the most valuable fisheries in the U.S., generating $360 million in revenue annually, and making the U.S. a global leader in wild scallop fishing.
A combination of conservation measures has helped the industry weather the effects of overfishing. Now, warming and acidifying oceans are posing new threats and prompting new solutions.
A team of researchers co-led by UConn Associate Professor of Marine Sciences Samantha Siedlecki, Shannon Meseck, of NOAA’s Northeast Fisheries Science Center, and Robert “Bobby” Murphy, a social scientist with NOAA’s Northeast Fisheries Science Center, is exploring how environmental data can be used to develop a new management approach adapted for and responsive to a changing ocean. With the support of a three-year grant of just over $1 million from NOAA’s Ocean Acidification Program (OAP), the project will integrate oceanographic modeling, industry engagement, and socioeconomic research to create actionable strategies for industry and management. The project is one of six announced by OAP in November aimed at helping U.S. coastal communities adapt to ocean acidification.
“This is one of the earliest attempts to forecast optimal regions for Atlantic sea scallop growth, based on both carbon content and ocean temperature,” says Siedlecki.
Carbon dioxide released into the atmosphere and absorbed by water lowers its pH level, making the ocean more acidic and less able to sustain life. In 2009 a group of scientists included this ocean acidification (OA) as one of nine planetary boundaries that must remain within safe bounds if the earth is to remain stable and resilient. That study recognised that ocean health is integral to the overall health of the planet. A more recent study concluded that by 2020 the planetary boundary for OA had already been crossed. It is the seventh of the boundaries to have been breached.
For over two decades, governments and international organisations have recognised the danger that OA poses to marine life, and by extension to economies and societies. Supported by a large volume of scientific research detailing the threat, measures to combat OA have been incorporated into numerous national policies and international agreements, including the United Nations Sustainable Development Goals (SDGs). But the crossing of the planetary boundary is a clear indicator that those efforts have failed.
Policy fragmentation, at both international and national levels, is a major reason for the lack of progress on OA. Seen in conflicting objectives, duplication and weak accountability for results, such fragmentation is, an issue across ocean management as a whole. Many experts believe that a more holistic, systems-based approach to ocean management can integrate OA action more effectively alongside parallel efforts to address other stressors of ocean and planetary health. In this article, they discuss why such an approach has potential to eventually turn the tide.
Winter School lecturer Sam Dupont, from the University of Gothenburg, demonstrates a technique for an experiment on sea urchin fertilization. (Photo: IAEA)
The IAEA is training early-career scientists to assess the impacts of ocean acidification and pollution, helping countries respond to environmental changes.
Marine biodiversity faces growing pressure from environmental changes and pollution. To help countries understand and respond to these combined threats, the IAEA is equipping young scientists with advanced skills to study the ocean’s most pressing challenges.
The Ocean Acidification International Coordination Centre (OA-ICC) trained 14 early-career scientists from around the world in key concepts and cutting-edge techniques to assess the impacts of environmental changes from multiple stressors on the ocean. The third edition of the OA-ICC Winter School on Ocean Acidification and Multiple Stressors was held at the IAEA Marine Environment Laboratories in Monaco from 24 November to 5 December 2025.
Threats to Ocean Health
The ocean faces multiple pressures, including from acidification, warming and pollution. These stressors threaten biodiversity and food security in many regions. Understanding their combined effects is essential to develop effective mitigation and adaptation strategies.
“Ocean acidification is not occurring in isolation, but expertise in studying multiple stressors is often lacking. The OA-ICC capacity building programme plays a key role in expanding this knowledge base,” said Lina Hansson, Associate Project Officer at the IAEA.
During the two-week course, participants learned best practices in experimental design and applied them in a hands-on laboratory study. They investigated the combined effects of ocean acidification, warming and lithium pollution on the reproductive success of a common Mediterranean Sea urchin.
Participants also visited the Laboratoire d’Oceanographie de Villefranche (LOV) in France for practical training in seawater chemistry monitoring and connected with researchers at the Centre Scientifique de Monaco. The Winter School emphasized science communication and community engagement. Through a series of guest lectures, participants explored principles for co-designing research, including integrating traditional knowledge from local communities.
“The Mediterranean Sea is heavily affected by multiple stressors. Record-breaking marine heatwaves, pollution, combined with acidification, have led to mass mortality of key species,” said Steeve Comeau, Research Scientist at LOV and Winter School lecturer. “Training this new generation in multifaceted experimental approaches is critical for predicting future impacts.”
The world’s oceans do far more than support vital marine ecosystems and provide food and recreation. They help regulate the Earth’s climate, absorbing vast amounts of heat and CO2, acting as one of the planet’s most important buffers against climate change.
Yet despite this vital role, scientists still struggle to track exactly how and where the ocean absorbs and stores CO2 – and how that process is changing.
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Rintala is leading an international team that aims to extend ocean observing capacity by developing sensors for platforms that can operate beyond normal shipping routes and deep below the surface – far from ships and human intervention
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At the heart of the effort is the development of the world’s first autonomous sensor capable of accurately measuring total alkalinity in the ocean – from the sea floor to the surface.
Total alkalinity is a key chemical indicator that scientists use to understand the ocean carbon system and estimate how much CO2 seawater can absorb and store.
It is also critical for tracking ocean acidification – a process driven by rising CO2 levels that lowers seawater pH and threatens marine ecosystems, particularly shell-building plankton and molluscs.
“Ocean acidification is very harmful for many marine organisms,” said Rintala. “It can cause cascading effects that ripple up the food web.”
Until now, total alkalinity has usually been measured by collecting fixed seawater samples from ships and analysing them later in onshore laboratories. That approach provides valuable data, but only at isolated points in time and space.
“If we are interested in the carbon content of the ocean as a whole, we need to measure deeper,” said ocean scientist Socratis Loucaides, based at the UK’s National Oceanography Centre (NOC).
Loucaides and his colleagues at NOC are leading the development of a radically different approach: a compact lab-on-a-chip sensor that performs a miniature chemistry experiment inside the instrument itself.
Inside the device, a small seawater sample is mixed with an acid of known strength and a dye that changes colour depending on acidity. A light-based sensor then reads those colour changes to calculate the alkalinity of the surrounding seawater.
By doing this directly in the deep ocean, the sensor can build up a far more detailed picture of how carbon is stored and transported over time – and potentially reveal early warning signs of change.
The Rhode Island aquaculture industry is more robust than ever. The value of aquaculture products was $8,795,493 in 2024 and 89 active aquaculture farms covered 392.5 acres, according to a report by the Rhode Island Coastal Resources Management Council.
Eastern oysters account for approximately 99% of the state’s aquaculture production, the report noted. Jacqueline Rosa, who is pursuing her master’s degree in oceanography from GSO, spent 18 months conducting field work on how water quality and farming practices impact these mollusks.
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Jacqueline Rosa (center) uses a water quality sensor to measure key parameters, including temperature, salinity, and pH during weekly sampling at Wickford Oyster Company in 2024. Rosa is accompanied by oyster farmers John McKillop (left) and Kevin Tuttle. (Photo courtesy of Gage Whilden)
To examine the environmental conditions, Rosa deployed two sensors at Wickford Oyster Company’s 4-acre farm in May 2024, one at the surface of the water and one at the bottom of the water column.
Rosa revisited the farm each week to collect water samples from the surface and the bottom. She brought the samples to the Ocean Carbon Laboratory at the Graduate School of Oceanography for analysis.
“I tested the samples for pH, salinity, alkalinity, and dissolved inorganic carbon,” said Rosa, who is from Newtown, Connecticut. “These carbonate chemistry parameters help us understand trends in ocean acidification and how changing conditions may impact calcifying organisms. Shifts in carbonate chemistry can influence shell formation, growth rates, and survival, particularly during early-life stages, making these measurements critical for understanding potential stressors for farmed oysters.”
13 January 2026/Kiel/Limassol. Today, Expedition M216 set sail for the Mediterranean Sea with the research vessel METEOR. An international research team led by GEOMAR Helmholtz Centre for Ocean Research will assess the state of the Mediterranean over the coming weeks. The research is conducted as part of a time series that was last carried out in 2018. The data collected now are therefore central to assessing current and future changes in the Mediterranean Sea. Among other things, temperature, salinity, nutrients and trace gases are being investigated, as well as the stratification and circulation of the water masses.
Like the Baltic Sea and the Black Sea, the Mediterranean Sea is an inland sea connected to the global ocean only by the Strait of Gibraltar. As a result, it responds more quickly to changes. It warms more rapidly, absorbs more carbon dioxide and acidifies more strongly than the open ocean. At the same time, through its connection with the Atlantic, the Mediterranean Sea also influences the global ocean and additionally plays an important role for the regional climate, fisheries and tourism.
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Several factors come together in the Mediterranean Sea: it has a very high salinity and pronounced water circulation. The high salt concentration and temperature promotes the uptake of anthropogenic CO2. At the same time, surface water is transported relatively quickly to the depth, where it remains at a temperature of around 12 to 13°C. In addition, the circulation ensures that deep water reaches the surface, which can again absorb CO2. This creates a dynamic cycle that enables the Mediterranean Sea to bind a comparatively large amount of CO2 from the atmosphere,” explains Dr Toste Tanhua, expedition leader and chemical oceanographer at GEOMAR.
Measurements from the surface to the sea floor
The measurements cover the entire water column, i. e. all layers of the Mediterranean Sea from the surface to the sea floor. At its deepest point, the Mediterranean Sea is over five thousand metres deep. “The unique topography of the Mediterranean Sea is challenging for us. There are several basins with different conditions and water depths,” says Toste Tanhua. The expedition focuses on measuring nutrients, salinity, oxygen, alkalinity, dissolved inorganic carbon, organic carbon, CO2 and the degree of ocean acidification. This enables the researchers to deduce how the Mediterranean Sea is faring under the influence of climate change and to estimate further changes. They are also investigating the distribution of water masses, currents and the exchange between surface water and the deep ocean.
“The Med-SHIP programme gives us the opportunity to take a very close look at the individual components of the entire water column. Among other things, we will be investigating inorganic carbon. This refers to carbon that is not found in living organisms, but in rocks, water or in the atmosphere as CO2. Among other things, it is responsible for transporting CO2 between the atmosphere, the surface and deep water. As the water masses in the Mediterranean are in contact with the atmosphere relatively frequent, this is particularly interesting for us,” explains Toste Tanhua.
Vermillion rockfish and soft coral observed during an expedition in Channel Islands National Marine Sanctuary. Image courtesy of Marine Applied Research and Exploration, NOAA.
When compared with historical samples, corals show that the Salish Sea and California Current System are acidifying faster than anticipated because of greenhouse gas emissions. Models indicate that at this rate, carbon dioxide levels in the oceans will continue rising faster than concentrations in the atmosphere.
Increasingly acidic seas pose growing risks to sensitive marine life, from clams and oysters to any organism with a spine, as well as economically important fisheries and the communities that depend on them.
British marine ecologist Stephen Widdicombe calls the threat existential. Our continued failure to cut emissions can only lead to “a world where uncontrolled climate change including ocean acidification leaves us with an ocean that is less productive, less diverse and less able to provide humans with the wealth of services that we currently all benefit from,” he said.
In 1888, researchers aboard the R/V Albatross began the world’s first concentrated marine research expeditions off California’s Pacific coast. The team collected untold plant and animal specimens, including orange cup corals, which they carefully preserved and stored in collections at the Smithsonian Institution.
These specimens have now become rare physical evidence of ongoing changes in the chemistry of the Pacific Ocean as seawater absorbs the carbon dioxide released into the atmosphere by burning fossil fuels.
Researchers recently analyzed these 130-year-old samples, which come from a time before the Industrial Revolution’s greenhouse gas impacts had really kicked in. Then they compared them with new specimens collected in the same locations by a team aboard another research vessel, the R/V Rachel Carson, in 2020.
They discovered that this region is acidifying, far faster than models have predicted, findings they recently published in the journal Nature Communications.
“Ocean acidification is not a distant or abstract phenomenon. It is already underway, it is amplified in some regions, and it has real consequences for ecosystems and coastal economies today,” study lead author Mary Margaret Stoll, from the University of Washington, told Mongabay.
This research focused on the Salish Sea and the cold California Current System, an interweave of four currents predominantly flowing south from the Canadian province of British Columbia to the Mexican state of Baja California. Prevailing winds push water away from the coast along these currents, drawing water up from the deep, bringing nutrient-rich sediments along with it. These support exceptional biodiversity and lucrative fisheries.
The Pacific Islands Ocean Acidification Centre hosted its second collective regional training on ocean acidification.The event not only enhanced the scientific skills of Pacific researchers but also strengthened a regional network dedicated to understanding and mitigating the growing impacts of ocean acidification across the Pacific.
The impact of ocean acidification on the balance of ocean ecosystems
The Intergovernmental Panel on Climate Change (IPCC) has said several times that ocean acidification is one of the most serious but often overlooked effects of growing levels of carbon dioxide (CO₂) in the air.
The IPCC’s Sixth Assessment Report (AR6) says that the ocean has absorbed over 30% of human-caused CO₂ emissions and more than 90% of the extra heat from global warming. Now, a new report from the Planetary Boundaries Science Lab reveals that seven out of nine planetary boundaries have been breached, with ocean acidification officially entering the danger zone.
The combined effects of warming and acidification are very harmful to marine species and to societies that depend on healthy ocean ecosystems. This is especially true in Small Island Developing States (SIDS) like those in the Pacific. Coral reefs that are deteriorating are harmful to fisheries and coastal protection, and the loss of marine biodiversity could jeopardise the tourist economy.
Understanding, monitoring, and responding to these changes is therefore not just a scientific need; it is a matter of survival for many island communities.
A School Supported by Lead Organizations in the Field
After two years of preparation, the GOOD-OARS Summer School took place on 4-11 November 2025 at the Centre for Marine and Coastal studies (CEMACS), Malaysia. Under the lead of the Intergovernmental Oceanographic Commission (IOC) of UNESCO, more than 10 partner organizations came together to support the summer school, including the two IOC-supported expert groups – the Global Ocean Oxygen Network (GO2NE) and the Global Ocean Acidification Network (GOA-ON) – as well as the the two Ocean Decade programmes – the Global Ocean Oxygen Decade (GOOD) and the Ocean Acidification Research for Sustainability (OARS).
Laboratory practical activity at @CEMACS
A School Combining Theoretical and Practical Training
During the summer school, early career scientists (ERCs) had the possibility to learn more about the drivers and impacts of ocean deoxygenation and acidification. The days were filled with lecturers introducing the scientific basis, hands-on training comprising observation and experimental techniques, science communication and outreach, as well as ethical considerations when conducting science. In line with the vision of the Ocean Decade, the school encouraged engagement with the end-users of science. A stakeholder event with the local aquaculture industry allowed participants to identify how new scientific findings might be applied by the private sector.
Oyster farms are one of the most environmentally sustainable farms in the world. As filter-feeders, oysters and other bivalve mollusks like clams, mussels, and scallops, require no additional feed or fertilizers. They simply eat plankton from their surroundings, leaving cleaner shallows for the rest of the ecosystem to enjoy.
However, the late 2000’s brought a concerning trend of oyster farm mortality events. One culprit is higher levels of carbon dioxide absorbed into our waters, which creates a more acidic environment. As climate change progresses, the oceans grow more acidic and less hospitable for shellfish.
“It affects many ocean organisms, but especially animals that build shells and skeletons,” says graduate student Leah Wessler. “It’s a big barrier for aquaculture and wild fisheries.”
Wessler is in the MSc program Applied Animal Biology studying how ocean acidification affects shellfish farms and how we can mitigate or even reverse the damage. From coral reefs in the Caribbean to beluga whales in Alaska, Wessler has worked in marine conservation and research around the world. She was drawn back home to the Pacific North West by a growing sense of optimism and momentum in the shellfish aquaculture sector.
“Here’s an avenue of farming that’s sustainable, produces high-quality protein, and is already quite common in many areas of the world,” Wessler says.
The premiere of the short film “Changing Waters: Time for Action on Ocean Acidification” showed leaders from around the world sounding the alarm on the need to tackle this overlooked climate threat by drastically reducing emissions.
Belém, Brazil, November 20th, 2025 – Yesterday evening, the Ocean Pavilion at COP30 filled with policymakers, scientists, and coastal leaders for the premiere of “Changing Waters: Time for Action on Ocean Acidification” – a short film that puts climate challenge into sharp focus and centers the voices of those witnessing and responding to its impacts firsthand.
Produced by the International Alliance to Combat Ocean Acidification (OA Alliance) and LUMA Storytelling, the film bears witness to the work of leaders around the globe – from Washington State, to Fiji and Colombia – showing how they are taking action to protect their coastal resources and documenting what’s at stake if carbon emissions are not drastically reduced.
“These partners see, every day, the effects of climate change on our ocean,” says Jessie Turner, Executive Director of the OA Alliance. “The film both celebrates their work and honors the sense of urgency we are demanding from global policymakers.”
Twenty-five years ago, a landmark paper warned that the world’s coral reefs could vanish by 2050. Now, halfway to that projected date (and amid ever more frequent coral bleaching events), that grim prediction feels increasingly close to reality. What is the current state of Earth’s coral reefs, and what would happen to our planetary home without them?
In this episode, Nate is joined by Ove Hoegh-Guldberg, the marine biologist who made this landmark prediction, for an update on the health of coral reefs and the primary ecological stressors driving their decline. Drawing on decades of research, he explains the mechanisms of coral bleaching, the critical biodiversity hotspots that reefs create, and the implications for human populations that depend on these ecosystems. Ove also touches on the emotional impact of witnessing the loss of reefs for the scientists who have dedicated their lives to studying them.
How are human actions increasingly putting pressure on the very ecosystems that support more than one billion people? What would happen to the broader health of the oceans if reefs were to disappear entirely? And most of all, what changes can both individuals and institutions make today to support the health of these vital ecosystems – and in-turn, the well-being of the entire Earth?
Written by Dr. Chris Hunt of the University of New Hampshire’s Ocean Process Analysis Laboratory, Curtis Bohlen, Director of Casco Bay Estuary Partnership, Mike Doan, Friends of Casco Bay’s Staff Scientist, and Jeremy Miller of Wells National Estuarine Research Reserve, the report shares the results of their two-year study to identify affordable and reliable tools for monitoring nearshore ocean acidification.
The first part of the report, “Assessment of Coastal Ocean Acidification Monitoring in Maine,” examines the accuracy of glass-electrode data sonde pH sensors. By testing real-world results of these sensors against laboratory-controlled methods, researchers found that sondes can reliably and effectively measure coastal pH when best practices are followed.
The second part of the report outlines those best practices and standard operating procedures.
Friends of Casco Bay’s and Wells NERR’s respective continuous monitoring programs use the quality assurance and best practices outlined in the report. The Sensor Squad is committed to sharing what they have learned with organizations, researchers, and agencies that are currently collecting continuous acidification data, or are interested in doing so in the near future.
Un rapport scientifique conclut que la limite de « l’acidification des océans » a été franchie en 2025, menaçant « la vie marine » sur Terre.
Brett Monroe Garner / Getty Images. Une septième « limite planétaire » vient d’être franchie, la Terre est en train de devenir inhabitable. (Photo d’un champ de coraux sur la Grande Barrière de Corail lors d’un épisode de blanchissement massif.)
Créées en 2009 sous l’impulsion du scientifique suédois Johan Rockström, les limites planétaires désignent les différents points à ne pas dépasser pour garder la planète dans un état vivable. Une trentaine de chercheurs estimaient il y a quinze ans que l’humanité avait « transgressé au moins trois limites planétaires ». Depuis, les bilans annuels de l’Institut de recherche sur le climat de Potsdam (PIK) ont montré une dégradation continue.
Celui de 2025 indique que la limite de « l’acidification des océans » vient d’être franchie. « L’océan est en train de s’acidifier, menaçant la vie marine et nous faisant entrer dans des conditions dangereuses, avec une tendance qui s’aggrave encore », ont écrit ses chercheurs. En d’autres termes, ce sont tous les écosystèmes marins qui sont menacés, comme en atteste le blanchissement des récifs coralliens, phénomène annonciateur de leur mort.
Excès de CO2 et révision des calculs
La principale cause de l’acidification des océans est l’absorption de dioxyde de carbone (CO2) émis avec la combustion d’énergies fossiles. Les scientifiques estiment que les océans ont absorbé environ 30 % de l’excès de CO2 relâché dans l’atmosphère par la combustion de pétrole, de gaz et de charbon.
La hausse de l’acidification par rapport aux chiffres publiés l’an dernier est également due en partie à une amélioration des données et à une révision des calculs.
Les six autres seuils déjà dépassées concernent le changement climatique (CO2 dans l’atmosphère), l’intégrité de la biosphère (extinction d’espèces et appropriation des ressources par l’humanité), mais aussi l’usage des sols (déforestation), le cycle de l’eau douce (zones touchées par la sécheresse ou les inondations), les cycles biogéochimiques (ajout d’engrais et pesticides) et l’introduction d’entités nouvelles dans la biosphère (plastiques et autres produits chimiques industriels).
The newly published 2025 Planetary Health Check report confirms transgression of the ocean acidification planetary boundary — the seventh Earth system threshold crossed, putting a “safe operating space for humanity” at risk. Oceans act as a key climate stabilizer, resilience builder and Earth life-support system.
Marking the launch of the 2025 Planetary Health Check, Mongabay speaks with report co-author and renowned Earth system scientist Johan Rockström about how the transgression of planetary boundaries is eroding environmental justice — the right of every human being to life on a stable, healthy planet.
Rockström, who led the international team of scientists who originated the 2009 planetary boundary framework, also speaks about the failure to achieve a U.N. plastics treaty in August and the challenge of accomplishing planetwide sustainability in a time of widespread armed conflict and political instability.
He likewise emphasizes the need to bring the U.S. back to the negotiating table at COP30, the U.N. climate summit scheduled for November, in Belém, Brazil, and addresses the importance of inserting the planetary boundaries framework into those talks.
Initiated in 2024, the Planetary Health Check is a comprehensive, science-based global initiative dedicated to measuring and maintaining Earth systems critical to life as we know it.
These annual reports were created to provide a regular, comprehensive assessment of the state of our world, utilizing the most current planetary boundaries science — monitoring changes, gauging risks, identifying urgent actions needed, developing solutions and determining progress in maintaining a “safe operating space for humanity.”
The just-published 2025 assessment finds that seven out of the nine critical planetary boundaries (PBs) have been breached: climate change, change in biosphere integrity, land system change, freshwater change, modification of biogeochemical flows, the introduction of novel entities, and now, ocean acidification.
All of these Earth system boundary transgressions show escalating trends, threatening further deterioration and destabilization of planetary health in the near future. Just two PBs remain within the safe operating space: increase in atmospheric aerosol loading (with an improving global trend) and stratospheric ozone depletion (currently stable).
Earth System scientist Johan Rockström, director of the Potsdam Institute for Climate Impact Research (PIK) in Germany, spoke to Mongabay on the occasion of the launch of the Planetary Health Check 2025 report, which announces the transgression of the ocean acidification boundary — the seventh Earth system boundary threshold crossed, putting the safe operating space for humanity at grave risk.
PIK’s director is co-author of the 2025 report and author of the book and video documentary Breaking Boundaries: The Science of Our Planet (2021), which explains the planetary boundaries framework, which was developed in 2009 by an international scientific team led by Rockström. This framework was also the inspiration for the Frontiers Planet Prize, which awards three prizes of $1 million every year to research offering the greatest potential to address the ecological crisis.
The newly released report signals a planetary emergency requiring immediate and coordinated global action, say scientists. (This interview has been lightly edited for brevity and clarity.)
This iconic planetary boundaries (PBs) diagram visually represents the current status of the nine critical PB processes that regulate our planet’s health. Each Earth system is quantified by one or more control variables based on observational data, model simulations and expert opinions. Image courtesy of Planetary Health Check 2025.
Mongabay: The Planetary Health Check 2025 report announces the transgression of the ocean acidification boundary (the decreasing of pH in seawater caused by the absorption of atmospheric CO₂), the seventh Earth boundary threshold to be crossed due to humanity’s actions. What does this mean and why is it relevant to all of us?
Johan Rockström: The latest update — based on data observations as to where [ocean] acidification is developing, and on the refined methodology for making those observations — concludes, unfortunately, but not unexpectedly, that the ocean acidification boundary has now been breached.
This is a very worrying trend, because the ocean is under multiple planetary pressures: [including] the faster than expected heat increase, the ocean acidification boundary now being breached, continuous eutrophication, and the loss in biodiversity due to overfishing and other causes. So, we have an ocean system on planet Earth, across all marine systems, under high and increased pressure.
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Julian Reingold, Mongabay, 24 September 2025. Full article.
We have breached 7 out of 9 Planetary Boundaries. The Planetary Health Check 2025 makes it clear: We have to act now.
Human activities have pushed Earth beyond its Safe Operating Space. The planet’s natural resilience is weakening: global warming is accelerating, ecosystems are showing clear signs of degradation, and early warning signs of tipping points are emerging in key systems. We have entered the Anthropocene — an era where human activity dominates the Earth system.
To saveguard the Earth’s resilience and stability, we must bring the planet back into its Planetary Boundaries. These boundaries are scientifically defined guardrails that ensure the Earth’s health. Stay within them, and the Earth stays our dependable home — breach them, and we risk irreversible damage to our very own life support system. Today, seven out of nine boundaries have been transgressed.
The Planetary Health Check is a yearly report on the state of our planet. It presents the most up-to-date assessments of the Planetary Boundaries, gives thorough introductions into cutting-edge science, and spotlights especially relevant aspects of our planet’s health. In this 2025 edition, we place a special focus on the Ocean’s role in the Earth system, and assess for the first time that Ocean Acidification is the seventh transgressed Planetary Boundary.
Planetary Health Check 2025
A Scientific Assessment of the State of the Planet
This second annual assessment of our planet’s health presents the most up-to-date Planetary Boundaries science. In focus this year: our ocean, and the role it plays for earth’s stability and habitability. Further spotlights include an investigation of the last year’s extreme weather events, and a landscape overview of efforts to put Planetary Boundary science into action.
The Planetary Boundaries Science (PBScience) project was launched in 2023 to address critical gaps in our understanding and monitoring of the Earth system. Utilizing advanced simulation modeling, incorporating the latest available measurement datasets and synthesizing new insights from Earth system science literature, PBScience provides annual Planetary Health Checks based on the Planetary Boundaries framework. Collaborating closely with the Planetary Guardians and other partners, PBScience strives to elevate global awareness and drive action towards maintaining planetary stability.
Twenty Pier2Peer mentee graduates, representing 17 countries, join the global professional community for ocean acidification monitoring and research. After successfully completing two years of one-on-one mentorship with experts in the field of ocean acidification, this cohort pursued capacity building projects with the guidance of their mentors, advancing their regions’ ability to measure and address ocean acidification. Half of the mentors of this year’s graduating class are U.S. based ocean acidification experts, demonstrating the strong international leadership the United States offers to ocean acidification science. Projects ranged from revitalizing a carbonate chemistry laboratory in the Galapagos Islands to understanding the impact of ocean acidification on coral reef ecosystems in the Gulf of Mannar.
Building capacity for ocean acidification tracking and forecasting means going beyond U.S. waters. As ocean acidification poses a threat to fisheries, aquaculture, and coastal communities in the U.S. and beyond, it is imperative that countries work together to train the next generation of experts to improve our global capacity to measure and address changing ocean chemistry. The mentorships often forge long-lasting relationships.
“What is more exciting is that I keep gaining other skills from my mentor as we implement the project, such as how to identify and understand the research gaps through a literature search and review.” -Anonymous Pier2Peer Mentee
The Pier2Peer program, coordinated through the Global Ocean Acidification Observing Network and administered by The Ocean Foundation, meets this need by pairing experienced researchers with scientists new to the field of ocean acidification. Mentorship pairing facilitates the transfer of knowledge, skills, and data, and ultimately expands the community of professionals working toward addressing impacts of changing ocean chemistry. As an international mentorship program, Pier2Peer facilitates international collaboration and capacity building to better prepare the United States and its neighbors to respond to ocean acidification. Pier2Peer also builds capacity through training and scholarships.
Ocean acidification, driven by anthropogenic carbon dioxide (CO₂) emissions, poses a severe threat to coral reef ecosystems worldwide, with significant implications for small island nations like Niue. This article examines the specific impacts of ocean acidification on Niue’s coral reefs, which are vital to the island’s biodiversity, economy, and cultural heritage. Through a situational analysis of Niue’s reefs and a review of global literature, the study highlights the chemical processes of acidification, its ecological consequences, and the socio-economic ramifications for Niue’s communities. The paper further explores the role of intergovernmental organizations and international treaties in addressing this crisis, emphasizing the need for coordinated global action. Recommendations are provided to mitigate acidification impacts through local conservation efforts, regional collaboration, and international policy advocacy. This article underscores the urgency of integrating ocean acidification into global climate agendas to protect vulnerable ecosystems like Niue’s coral reefs.
Ocean acidification, a consequence of rising atmospheric carbon dioxide (CO2) levels, poses a significant threat to global marine ecosystems by altering ocean chemistry and disrupting marine life. While Bhutan, a landlocked Himalayan nation, may seem distanced from direct oceanic impacts, its commitment to environmental conservation and sustainable development positions it as a unique contributor to global marine conservation efforts. This paper explores the broader impacts of ocean acidification on marine biodiversity and human communities, examining Bhutan’s potential role within the international framework of marine conservation. Through an analysis of intergovernmental organizations, treaties, and Bhutan’s environmental policies, the study highlights how a non-coastal nation can indirectly support marine conservation through climate mitigation, sustainable practices, and international collaboration. Recommendations are provided for Bhutan to enhance its role in addressing ocean acidification through policy advocacy, capacity building, and partnerships with global environmental bodies.
Panarea Island, in the Aeolian Archipelago, served as a unique environmental setting for a pilot study on the impact of CO2 on calcifying phytoplankton and zooplankton, in an area characterized by the presence of natural CO2 seeps on the seafloor.
This research allowed scientists from ICTA-UAB and the National Institute of Oceanography and Experimental Geophysics (OGS) of Italy to directly address the impact of these CO₂ leaks and ocean acidification on the ecosystems, as well as the species-specific physiological responses, including the calcification processes.
Oceans absorb a large amount of atmospheric carbon dioxide, which helps mitigate climate change. In certain areas, such as volcanic zones near Sicily, natural CO₂ emissions from the seafloor can be observed. These leaks alter the water chemistry and may have consequences for marine life.
The study of biodiversity changes resulting from these leaks will deepen the understanding of the role of calcifying plankton in ocean carbon sequestration and will provide valuable insights into their influence on the biogeochemical carbon cycle. This first pilot study greatly benefited from the existing OGS marine laboratory facilities at Panarea.
