Chronic diclofenac (DCF) exposure was tested in Daphnia magna at pH 7.0 and 8.7.
An unexpected pH increase in M4 medium was observed during the experiment.
The NOEC (no observed effect concentration) of DCF was 5 mg l-1 at pH 8.7.
Initial pH 7.0 prolonged the time to release of the first hatchlings.
At 1.3 mg l-1 DCF, fewer neonates were observed at pH 7.0 than at pH 8.7.
Abstract
Pharmaceuticals, as ionizable compounds, are a challenging group of pollutants to analyze because the pH of the environment can alter its ecotoxicological features. However, changes in the toxicity of pharmaceuticals toward aquatic organisms were observed even when there was no change in the ionization of the molecules with a pH shift. Therefore, we conducted a study that aimed to check how pH influences the chronic toxicity of diclofenac (DCF, pKa ≈ 4.0) toward Daphnia magna at two pH levels, 7.0 and 8.7, where DCF is obtained as relatively polar anion. The performance of the experiment with OECD 211 was found to be challenging because of the medium pH shift during the exposure test. Acidification increased the toxicity of DCF, reducing the number of neonates (at a concentration of 1.3 mg l-1) and showing a tendency towards delayed hatching and reduced number of hatchings. In addition, the acidification itself also changes D. magna reproduction, affecting the number of hatchings and the first day of hatching. We conclude that the pH, as a factor of toxicity modulation for ionizable compounds, needs to be evaluated and presented in scientific protocols.
The history of resilience of organisms over geologic timescales serves as a reference for predicting their response to future conditions. Here we use fossil Porites coral records of skeletal growth and environmental variability from the subtropical Central Paratethys Sea to assess coral resilience to past ocean warming and acidification. These records offer a unique perspective on the calcification performance and environmental tolerances of a major present-day reef builder during the globally warm mid-Miocene CO2 maximum and subsequent climate transition (16 to 13 Ma). We found evidence for up-regulation of the pH and saturation state of the corals’ calcifying fluid as a mechanism underlying past resilience. However, this physiological control on the internal carbonate chemistry was insufficient to counteract the sub-optimal environment, resulting in an extremely low calcification rate that likely affected reef framework accretion. Our findings emphasize the influence of latitudinal seasonality on the sensitivity of coral calcification to climate change.
This study assesses the impact of intensified upwelling on the marine carbonate system along the Northwest African coast, from Cape Blanc (21°N) to Cape Cantin (33°N), a region where ocean acidification observations remain limited. We analyze surface water variability using data from two oceanographic surveys conducted aboard the R/V Dr. Fridtjof Nansen in spring and autumn 2022. The analysis is based on observational data of temperature, salinity, dissolved oxygen, chlorophyll a, pH, total alkalinity, and derived carbonate system variables. In spring, upwelling was widespread across the study area, while in autumn it was more localized near Cape Draa (28°30’N), between Cape Boujdour and Dakhla (25°30N–23°30N), and at Cape Blanc (21°N). Both spring and autumn were influenced by low-oxygenated South Atlantic Central Water (SACW), which is rich in DIC (2160–2250 µmol/kg), and upwelled to the surface, lowering pH (~7.85–7.95) and aragonite saturation state (ΩAr ~1.5–2.5). The strongest acidification signals were observed in autumn at Cape Draa (28°30N) and Cape Blanc (21°N), where the lowest pH (7.8) and ΩAr (1.5), along with the highest DIC (2250 µmol/kg), were recorded. The study clearly shows that the lowest pH values and highest DIC concentrations were related to the influence of SACW upwelling at Cape Blanc. It was also evident that areas with high chlorophyll a coincided with higher ΩAr and pH in spring. This suggests that primary production (PP) during spring counteracts the effect of upwelled low-pH water along the coast. Areas of high PP, such as at Cape Draa (28°30N), experienced increased DIC levels and enhanced acidification after the bloom season, potentially influenced by organic matter remineralization. Our findings highlight the influence of upwelling and biological processes on surface carbonate chemistry along the Northwest African coast. This study emphasizes the necessity of long-term monitoring to assess ocean acidification trends and their ecological implications in this vulnerable region.
I chat about the latest science on Ocean Acidification exceeding the safe planetary boundary in 2020. As global industry continues to accelerate the burning of fossil fuels pumping ever increasing amounts of Greenhouse Gases into the atmosphere, the oceans attempt to absorb more and more of the CO2, greatly increasing the ocean acidity.
Here is all the latest, and not so greatest on global ocean acidification. Since colder water can dissolve more GHGs, the polar oceans are the region facing the greatest ocean acidification threat. However, ocean acidification is still increasing enough in the lower latitude regions posing increasing risk to global coral reefs.
ABSTRACT
Ocean acidification has been identified in the Planetary Boundary Framework as a planetary process approaching a boundary that could lead to unacceptable environmental change. Using revised estimates of pre-industrial aragonite saturation state, state-of-the-art data-model products, including uncertainties and assessing impact on ecological indicators, we improve upon the ocean acidification planetary boundary assessment and demonstrate that by 2020, the average global ocean conditions had already crossed into the uncertainty range of the ocean acidification boundary. This analysis was further extended to the subsurface ocean, revealing that up to 60% of the global subsurface ocean (down to 200 m) had crossed that boundary, compared to over40% of the global surface ocean. These changes result in significant declines in suitable habitats for important calcifying species, including 43% reduction in habitat for tropical and subtropical coral reefs, up to 61% for polar pteropods, and 13% for coastal bivalves. By including these additional considerations, we suggest a revised boundary of 10% reduction from pre-industrial conditions more adequately prevents risk to marine ecosystems and their services; a benchmark which was surpassed by year 2000 across the entire surface ocean.
Scientists have known for decades that soaring atmospheric carbon dioxide emissions are causing changes in ocean chemistry, threatening marine life and ecosystems.
In June 2025, a study found that ocean acidification has passed a safe threshold across large swathes of the world’s marine environment, not only near the sea surface, but also up to 200 meters (656 feet) deep. The effect is especially severe in polar regions.
Ocean acidification is an added stressor to marine life already facing pressure from multiple threats connected to climate change (including marine heatwaves and reduced oxygen levels in seawater), along with other direct human impacts including pollution, overfishing and deep-sea mining.
Carbon emissions need to be deeply slashed and ocean protections greatly enhanced to allow ecosystems time to adapt and one day recover, say experts.
Ocean health is moving into a danger zone, with rampant human-caused carbon dioxide emissions having already pushed ocean acidification levels beyond safe limits in large swaths of the marine environment, according to a recent study. The new findings underline the urgent need to ramp up protection of the world’s oceans, while simultaneously slashing CO2 emissions, say experts.
But from a scientific perspective, worsening ocean acidification is not an overly surprising finding, considering that carbon dioxide emissions remain high, says lead author Helen Findlay, a biological oceanographer at the Plymouth Marine Laboratory in the U.K.
Researchers have known for decades that humanity’s CO2 emissions are being absorbed by seawater, triggering chemical reactions that release hydrogen ions, in turn reducing the abundance of carbonate ions. This ocean acidification process — which has escalated in tandem with atmospheric emissions — has implications for a large number of ocean-dwelling calcifying species that rely on calcium carbonate for their shells, with harm to those species potentially reverberating throughout marine ecosystems.
Workshop participants prepared alkaline solutions for laboratory experiments to study the effect of OAE on sea urchins. (C.Galdino/IAEA)
Researchers from around the world took part in a first-of-its-kind training course focused on the ecological impacts of Ocean Alkalinity Enhancement (OAE), an emerging method for carbon dioxide (CO2) removal. Hosted by the IAEA’s Ocean Acidification International Coordination Centre (OA-ICC) from 7 to 11 April 2025 at the IAEA Marine Environment Laboratories in Monaco, the training course equipped scientists to evaluate the impacts of OAE on marine organisms.
Urgency is growing to curb carbon dioxide (CO2) emissions to limit global warming to 1.5°C above pre-industrial levels. While drastically cutting CO2 emissions remains the highest priority, approaches are being explored to remove CO2 from the atmosphere as a part of the effort to address global warming. More recently, interest has grown in marine CO2 removal techniques that could harness the ocean to remove atmospheric CO2. But scientists still have major questions about the effectiveness and ecological impacts of these emerging techniques.
OAE is a marine CO2 removal method that has the potential to increase the ocean’s capacity to absorb atmospheric CO2 by changing ocean chemistry through the addition of alkaline materials, such as lime or olivine. OAE also has the potential to mitigate ocean acidification, which is the increase in ocean acidity driven by excess CO2 emissions that threatens marine ecosystems and coastal communities. However, the impacts of OAE on marine life are poorly understood.
The OA-ICC organized the course in partnership with the Prince Albert II of Monaco Foundation through the Ocean Acidification and other ocean Changes – Impacts and Solutions (OACIS) Initiative. This course leveraged the OA-ICC’s more than 12 years of experience training scientists in testing the effects of changing seawater chemistry on marine organisms through its ocean acidification capacity building programme.
The ocean absorbs one quarter of the global CO2 emissions from human activity. The community-led Surface Ocean CO2 Atlas (www.socat.info) is key for the quantification of ocean CO2 uptake and its variation, now and in the future. SOCAT version 2025 has quality-controlled in situ surface ocean fCO2 (fugacity of CO2) measurements on ships, moorings, sailing yachts, autonomous and drifting surface platforms for the global ocean and coastal seas from 1957 to 2025. The main SOCAT synthesis and gridded products contain fCO2 values with an estimated accuracy of better than 5 μatm. Sensor fCO2 data with an estimated accuracy of better than 10 μatm are separately available. During secondary quality control, marine scientists assign a flag to each data set, as well as WOCE flags of 2 (good), 3 (questionable) or 4 (bad) to individual fCO2 values. Data sets are assigned flags of A and B for an estimated accuracy of better than 2 μatm, flag of C (and D) for an accuracy of better than 5 μatm and a flag of E for an accuracy of better than 10 μatm. Bakker et al. (2016) describe the quality control criteria used from SOCAT version 3 onward. SOCAT quality control cookbooks provide quality control updates (www.socat.info), with (Gkritzalis et al., 2024) used for version 2025. Quality control comments for individual data sets can be accessed via the SOCAT Data Set Viewer (www.socat.info). All data sets, where data quality has been deemed acceptable, have been made public. The main SOCAT synthesis files and the gridded products contain all data sets with an estimated accuracy of better than 5 µatm (data set flags of A to D) and fCO2 values with a WOCE flag of 2. Access to data sets with an estimated accuracy of better than 10 µatm (flag of E) and fCO2 values with flags of 3 and 4 is via additional data products and the Data Set Viewer (Table 8 in Bakker et al., 2016). SOCAT publishes a global gridded product with a 1° longitude by 1° latitude resolution without gap filling. A second product with a higher resolution of 0.25° longitude by 0.25° latitude is available for the coastal seas. The gridded products contain all data sets with an estimated accuracy of better than 5 µatm (data set flags of A to D) and fCO2 values with a WOCE flag of 2. Gridded products are available monthly, per year and per decade. Two powerful, interactive, online viewers, the Data Set Viewer and the Gridded Data Viewer (www.socat.info), enable investigation of the SOCAT synthesis and gridded data products. SOCAT data products can be downloaded. Matlab code is available for reading these files. Ocean Data View also provides access to the SOCAT data products (www.socat.info). SOCAT data products are discoverable, accessible and citable. The SOCAT Data Use Statement (www.socat.info) asks users to generously acknowledge the contribution of SOCAT scientists by invitation to co-authorship, especially for data providers in regional studies, and/or reference to relevant scientific articles. It also asks users to cite the relevant SOCAT data set, the relevant methods paper(s), and to use acknowledgement text (https://socat.info/index.php/citing-socat/). The SOCAT website (www.socat.info) provides a single access point for online viewers, downloadable data sets, the Data Use Statement, a list of contributors and an overview of scientific publications on SOCAT and using SOCAT. Automation of data upload and initial data checks have allowed annual releases of SOCAT from version 4 onwards. Automation of metadata upload is ongoing. SOCAT is used for quantification of ocean CO2 uptake and ocean acidification and for evaluation of earth system models and sensor data. SOCAT products inform on ocean CO2 uptake in the annual Global Carbon Budget since 2013. SOCAT is a key element of the World Meteorological Organization’s (WMO) Global Greenhouse Gas Watch (G3W) program and is a key resource for Copernicus’ evaluations. The annual SOCAT releases by the SOCAT scientific community contribute to United Nations (UN) Sustainable Development Goal (SDG) 13 and SDG 14 (Life Below Water), and to the UN Decade of Ocean Science for Sustainable Development. However, since 2022 SOCAT critically relies on support provided by the Pacific Marine Environmental Laboratory of the National Oceanic and Atmospheric Administration in the US. This has been sufficient to keep the basic operation running, however this limited support has resulted in SOCAT data architecture not being updated, leading to a system with limited resilience that is highly vulnerable to external factors. Hundreds of peer-reviewed scientific publications and high-impact reports cite SOCAT. The SOCAT community-led synthesis product is a key step in the value chain based on in situ surface ocean carbon measurements, which provides policy makers with critical information on ocean CO2 uptake for policy makers. The need for accurate knowledge of global ocean CO2 uptake and its (future) variation makes sustained funding of in situ surface ocean CO2 observations and their synthesis imperative.
Global ocean acidification driven by atmospheric CO2 uptake is well recognized; however, coastal zones are subject to additional, localized acidification pressures. Among these, the chronic discharge of low pH treated wastewater (often pH 6.0), permitted under many current regulations, represents a significant but often overlooked stressor. This practice introduces highly acidic loads into sensitive nearshore ecosystems that are chemically incompatible with ambient seawater (pH ∼8.1). This perspective argues for reframing effluent pH not only as a pollutant parameter to be bounded but also as a modifiable policy lever. Revising discharge standards to require a minimum effluent pH > 8.0 for marine outfalls offers a novel pathway to mitigate localized coastal acidification. Furthermore, this approach aligns with emerging ocean alkalinity enhancement strategies, potentially enhancing coastal carbon sequestration and offering cobenefits such as reduced metal toxicity. Such a policy shift necessitates technological adaptation but promises significant benefits for coastal resilience and broader ocean sustainability goals.
Offspring/persistent OA plus OW aggravated IHg toxicity in T. japonicus.
Persistent OA had stronger mitigating effect on IHg toxicity than offspring OA.
OA plus OW intensified IHg toxicity in copepods mainly via lysosome dysfunction.
Persistent OA enhanced energy metabolism and Hg efflux, decreasing IHg toxicity.
Different scenarios of climate change can variably affect IHg toxicity in copepods.
Abstract
Dynamic shifts in multiple stressors are frequent in the marine environment. Here, we conducted a multigenerational experiment (F1-F4) to explore how different temporal scenarios of climate change, i.e., offspring/persistent ocean acidification (OA), warming (OW), and their combination (AW), could affect inorganic mercury (IHg) toxicity in the marine copepod Tigriopus japonicus. We found that persistent OA exhibited stronger mitigating effect on IHg toxicity in copepods than offspring OA, while offspring/persistent OW and AW aggravated its toxicity effects. We specifically performed transcriptomic analysis for the copepods of F4. Our transcriptomic result showed energy metabolism and detoxification were activated by persistent OA, enabling the copepods to resist IHg exposure. Instead, detoxification- and reproduction-related processes were inhibited in IHg-treated copepods under offspring/persistent OW and AW scenarios. Although apoptosis was suppressed to probably protect IHg-treated copepods under persistent AW, oxidative stress and lysosomal dysfunction ultimately caused reproductive impairment. Our study highlights that offspring/persistent (i.e., developmental/transgenerational) OA and OW could differentially modulate Hg toxicity in marine copepods, and more studies should focus on the temporal variation and complex interaction of multiple stressors, helping accurately project marine biota’s response in the future ocean.
Riverine diluted water and oxygen consumption dominate summer Ωarag decline.
Estuaries are more vulnerable to acidification under low-alkalinity river inputs.
A risk-assessment scheme of estuarine acidification is proposed.
Abstract
Seawater aragonite saturation state (Ωarag) is crucial for growth of calcifying organisms. Water with an Ωarag below 1.5 restricts marine shellfish growth and threatens the aquaculture industry’s health. Based on data of three summertime cruises along the Pearl River Estuary (PRE), China, we found that both low salinity (SP) and high apparent oxygen deficit (AOD) decreased Ωarag. Semi-quantitative results showed that either low SP of <15 (inducing calcium concentration decline) or high AOD of >100 μmol/kg (revealing organic-matter remineralization and a consequent CO2 rise) led to critical Ωarag values of <1.5. Moreover, the combination of moderate SP and a moderate AOD also led to critically low Ωarag values, potentially threatening the coastal aquaculture industry of shellfish. Taking a relatively dry year in 2023 as the case, the freshwater-endmember alkalinity exhibited a relatively low value of 1326 μmol/kg before the Pearl River flood, and ΩaragPre-flood = 0.0101 × (8.26 × SP – 123/138 × AOD) + 0.02 in the PRE mixing zone. After the Pearl River flood, the freshwater-endmembe alkalinity was added to a relatively high value of 1510 μmol/kg, while ΩaragPost-flood = 0.0102 × (5.59 × SP – 123/138 × AOD) + 1.20. These formulae performed pretty well in warning the ecological risk of the PRE carbonate chemistry below and/or around the critical Ωarag value of 1.5, providing idea for publics to easily assess potential ecological risk of the coastal Ωarag decline.
Washington, DC – U.S. Senators Sheldon Whitehouse (D-RI) and Lisa Murkowski (R-AK), and Representatives Chellie Pingree (ME-01) and James Moylan (R-GU) reintroduced the bipartisan, bicameral Coastal Communities Ocean Acidification Act. The legislation will strengthen coordination and collaboration between federal, state, local, and tribal entities on ocean acidification research and monitoring.
“The oceans are in trouble. Ocean acidification caused by carbon pollution is harming marine ecosystems and coastal industries like aquaculture,” said Whitehouse, Co-Chair of the Senate Oceans Caucus. “Our bipartisan legislation will assist in monitoring changes to the oceans and help us better understand how to protect Rhode Island’s blue economy from acidifying waters.”
“The impacts of ocean acidification on our coastal communities cannot be understated, particularly on our blue economy,” said Murkowski, Co-Chair of the Senate Oceans Caucus. “This legislation takes a holistic approach to understanding ocean acidification, encouraging experts from every walk of life to work together and ensure that our oceans stay healthy.”
The legislation would direct the National Oceanic and Atmospheric Administration (NOAA) to collaborate with and support state, local, and tribal entities that are conducting or have completed ocean acidification vulnerability assessments. The bill also strengthens partnerships between NOAA and a wide range of stakeholders involved in ocean acidification research, such as indigenous groups, coastal communities, state and local resource managers, fishery management councils and commissions, and the U.S. Integrated Ocean Observing System.
About thirty percent of carbon dioxide that is released into the atmosphere is absorbed by the ocean. The CO2 dissolves into seawater through a series of chemical reactions, increasing the overall acidity of the ocean. Increased seawater acidity hampers the growth and survival of young oysters and other shellfish by eating away at their shells. In 2017, Whitehouse conducted a science experiment on the Senate floor to show what happens when CO2 enters our oceans.
The Coastal Communities Ocean Acidification Act passed the House in the 118th Congress.
Ocean acidification has been identified in the Planetary Boundary Framework as a planetary process approaching a boundary that could lead to unacceptable environmental change. Using revised estimates of pre-industrial aragonite saturation state, state-of-the-art data-model products, including uncertainties and assessing impact on ecological indicators, we improve upon the ocean acidification planetary boundary assessment and demonstrate that by 2020, the average global ocean conditions had already crossed into the uncertainty range of the ocean acidification boundary. This analysis was further extended to the subsurface ocean, revealing that up to 60% of the global subsurface ocean (down to 200 m) had crossed that boundary, compared to over 40% of the global surface ocean. These changes result in significant declines in suitable habitats for important calcifying species, including 43% reduction in habitat for tropical and subtropical coral reefs, up to 61% for polar pteropods, and 13% for coastal bivalves. By including these additional considerations, we suggest a revised boundary of 10% reduction from pre-industrial conditions more adequately prevents risk to marine ecosystems and their services; a benchmark which was surpassed by year 2000 across the entire surface ocean.
L’impact de l’acidification de la mer Méditerranée sur la biodiversité marine est un sujet d’actualité préoccupant… Mais, certains êtres vivants semblent tirer leur épingle du jeu face à cette acidification : les herbiers marins de posidonie ! Mais jusqu’à quand ? La classe des 5e 2 du collège Albert Camus vous invite à découvrir ce trésor de la méditerranée, peu connu du grand public à travers leur émission « Radio Camus 06 s’exprime ! » Crédits : Remerciement à M. Gattuso (IMEV) pour cette entrevue enrichissante, Mme Hansson (IAEA) pour la documentation, à Mme Dargent pour son écoute et ses conseils, aux professeurs et à la classe de 5e2 pour la mise en œuvre du projet mené finalisé et à toutes les personnes qui ont participé au podcast : Emma, Iloé, Sophie, Camille, Nichita, Francesco, Amy, Manon, Sacha, Carla, Nolhan, Hadrien, Mme Cali, M. Sanchez, Mme Heams-Nérac, M. Lombardo.
The ocean and the atmosphere are constantly seeking balance.
Gases like oxygen, nitrogen, and carbon move between the ocean’s surface and the atmosphere by billions of metric tons every year.
A higher concentration of one gas in the atmosphere leads to more of that gas being taken up by the ocean as the two try to reach a state of balance – or equilibrium. However higher concentrations of carbon, emitted by human activities predominantly through the burning of fossil fuels, have been observed in the atmosphere since the Industrial Revolution.
This has consequently led to an increase in the ocean’s accumulation of carbon globally. This increase in ocean carbon has caused a chain of chemical reactions driving one of the primary environmental threats to marine ecosystems, fisheries and coastal communities – ocean acidification.
Carbon dioxide absorbed at the ocean’s surface binds with water molecules to produce an acid known as carbonic acid (H2CO3), which dissociates into bicarbonate ions (HCO3–) and a free-floating hydrogen ion (H+).
A rise in hydrogen ions is what changes the pH of any liquid, lowering the pH and making it more acidic.
Ocean water is turning ever so slightly more acidic, and that small shift has now pushed the chemistry of the sea past a point that scientists once marked as the global “do not cross” line.
A new assessment shows that by 2020 the average concentration of calcium carbonate, a building block for shells and reefs, had fallen more than 20 percent from pre‑industrial levels in many regions.
This results in a thinning of nature’s protective shield for corals, oysters, other mollusks, and countless plankton.
“Ocean acidification isn’t just an environmental crisis, it’s a ticking timebomb for marine ecosystems and coastal economies,” said Professor Steve Widdicombe of Plymouth Marine Laboratory, after reviewing the study.
How carbon drives ocean acidity
One extra molecule of carbon dioxide in the air means another will slip into the sea, combine with water, and release a hydrogen ion.
Until now, ocean acidification has not been deemed to have crossed its ‘planetary boundary’, but a major new study led by the UK’s Plymouth Marine Laboratory and the US-based NOAA – also launched this week – found the safety limit was reached five years ago.
Marking a significant milestone in Indigenous-led environmental stewardship, the Makah Tribe of Noah Bay in Washington has detailed the launch of their Ocean Acidification Action Plan during the 2025 United Nations Ocean Conference in Nice, France this week.
The announcement was made during a special side event hosted by the International Alliance to Combat Ocean Acidification in recognition of the gathering political momentum surrounding action on ocean acidification.
An alarming report was issued this week to coincide with the UN Ocean Conference in which scientists warned that ocean acidification was a ‘ticking time bomb’ and far worse than first feared.
Until now, ocean acidification has not been deemed to have crossed its ‘planetary boundary’, but a major new study led by the UK’s Plymouth Marine Laboratory and the US-based NOAA has found this safety limit was reached five years ago.
It’s a crisis that is contributing to the pressures being faced by coral reef ecosystems, the loss of habitats, and a threat to the survival for shell-building marine creatures by reducing the availability of calcium carbonate – a crucial building block that many of these marine organisms need to form shells and skeletons.
For Millennia, the Makah People’s culture, well-being, and economy have been intrinsically linked to the ocean’s bounty, with fish, shellfish, and other marine resources playing a role in food security, livelihoods, and cultural practices and traditions.
But today, many of the marine species on which the Makah tribe’s livelihood and traditions depend are at risk from ocean acidification.
It occurs when the ocean absorbs excess carbon dioxide from the atmosphere, setting off chemical reactions that acidifies seawater. This chemical alteration threatens marine organisms that rely on carbonate-based shells and skeletons, creating cascading effects that can knock entire marine ecosystems out of balance.
The Makah tribe is located in a region that was the first in the world to observe the impacts of changing ocean chemistry on traditional foods, including shellfish. Their Action Plan is a decisive step towards addressing this critical issue with Indigenous perspectives and priorities, combined with scientific research.
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While here at the UN Ocean Conference, Makah Tribe Natural Resource Policy lead, Mr Anthony Bitegeko was joined by the Portuguese Secretary of State of Fisheries and Maritime Affairs, Salvador Malheiro as well as Ms Mette Westergaard Bech, team leader on Ocean Acidification, Ministry of Environment and Gender Equality for Denmark to release the Ocean Acidification Action Plans.
They join countries such as Greece, Mexico, Fiji, Palau, Canada, and the UK in creating an action plan.
Key components of the action plan include integrating ocean acidification across mainstream climate, ocean, and coastal management plans; establishing cross-sector partnerships to ensure regional ocean acidification science is being applied to local decision making; developing educational initiatives; and advocating for policy changes at local, state, and federal levels.
“It’s clear that governments can no longer afford to overlook acidification in mainstream policy agendas,” said Ocean Acidification Alliance execrative director, Jessie Turner.
“That’s why we are so proud and encouraged by members of the National Ocean Acidification Action Planning Leadership Circle as they do the hard work to ensure that action on ocean acidification and climate change is a critical part of domestic and multilateral agendas.”
The Makah Tribe’s story is just one of many, with coastal communities around the world already concerned about the impact of ocean acidification.
Professor Steve Widdicombe, co-chair of the Global Ocean Acidification Observing Network and the co-focal point for the UN’s Sustainable Development Goal 14 target 3 – aiming to minimise and address the impacts of ocean acidification.
After a week of deliberation and discussion, the United Nations Ocean Conference today by consensus adopted a political declaration titled “Our ocean, our future: united for urgent action”, stressing that the ocean plays an essential role in mitigating the adverse effects of climate change.
“The ocean is fundamental to life on our planet and to our future, and we remain deeply alarmed by the global emergency it faces”, the Conference’s outcome document (A/CONF.230/2025/L.1) said, adding also: “Action is not advancing at the speed or scale required to meet Goal 14 and realize the 2030 Agenda [for Sustainable Development]”.
The declaration, also known as the “Nice Ocean Action Plan”, expressed deep concern that the ability of the ocean and its ecosystems to act as a climate regulator and to support adaptation has been “weakened”.
Underlining the importance of interlinkages between the ocean, climate and biodiversity, the declaration called for enhanced global action to minimize the impact of climate change and ocean acidification. It emphasized the particular importance of implementing various UN agreements and frameworks, recognizing that it would significantly reduce the risks and impacts of climate change and help to ensure the health, sustainable use and resilience of the ocean.
Further emphasizing the need to adapt to the “unavoidable effects” of climate change, the declaration affirmed the importance of the full and effective implementation of the Convention on Biological Diversity and its Protocols, as well as the Kunming-Montreal Global Biodiversity Framework.
Bivalves play a key role in coastal ecosystems and provide society with many ecosystem services. Anthropogenic activities produce a multitude of interacting stressors which can cause unexpected responses in the physiology, behaviour, condition, development, reproduction and survival of bivalves. Responses can be (1) additive: the response is the sum of the effect of individual stressors, (2) synergistic: the combined effect is greater than the sum of individual stressors or, (3) antagonistic: the combined effect is smaller than the sum of individual stressors. There has been a proliferation of research on the effects of multiple stressors on marine bivalves but an evaluation of the literature in the context of management and restoration has not been undertaken. This review and meta-analysis aimed to determine bivalves’ responses to stressor interactions and identify research trends and gaps. The meta-analysis highlights a prevalence of antagonistic and additive responses to stressors and an overall antagonistic effect. The observed antagonistic responses may be associated with how multiple stressor studies are being conducted. The literature demonstrates a bias towards individual-level laboratory experiments that focus on responses of adult bivalves to climate-change related ‘global’ stressors. Suggestions for future research include an emphasis on (1) ‘local’ stressors, (2) earlier life stages, and (3) field-based studies incorporating stressor gradients and spatiotemporal variability. These investigations will complement the existing knowledge base and ultimately provide a more complete picture of the impacts of multiple stressors on bivalves– information that is vital for management decision-making and restoration of bivalve populations.
Researchers have found that ocean acidification entered a “danger zone” in 2020, suggesting increased carbon dioxide levels have caused Earth to breach another planetary boundary.
The new study suggests our planet’s oceans are becoming too acidic to remain healthy. (Image credit: Philip Thurston via Getty Images).
Earth’s oceans are in worse condition than scientists thought, with acidity levels so high that our seas may have entered a “danger zone” five years ago, according to a new study.
Humans are inadvertently making the oceans more acidic by releasing carbon dioxide (CO2) through industrial activities such as the burning of fossil fuels. This ocean acidification damages marine ecosystems and threatens human coastal communities that depend on healthy waters for their livelihoods.
Previous research suggested that Earth’s oceans were approaching a planetary boundary, or “danger zone,” for ocean acidification. Now, in a new study published Monday (June 9) in the journal Global Change Biology, researchers have found that the acidification is even more advanced than previously thought and that our oceans may have entered the danger zone in 2020.
The researchers concluded that by 2020, the average condition of our global oceans was in an uncertainty range of the ocean acidification boundary, so the safety limit may have already been breached. Conditions also appear to be worsening faster in deeper waters than at the surface, according to the study.
“Ocean acidification isn’t just an environmental crisis — it’s a ticking time bomb for marine ecosystems and coastal economies,” Steve Widdicombe, director of science and deputy chief executive at Plymouth Marine Laboratory, a marine research organization involved in the new study, said in a statement. “As our seas increase in acidity, we’re witnessing the loss of critical habitats that countless marine species depend on and this, in turn, has major societal and economic implications.”
In 2009, researchers proposed nine planetary boundaries that we must avoid breaching to keep Earth healthy. These boundaries set limits for large-scale processes that affect the stability and resilience of our planet. For example, there are boundaries for dangerous levels of climate change, chemical pollution and ocean acidification, among others.
A 2023 study found that we had crossed six of the nine boundaries. The authors of that study didn’t think the ocean acidification boundary had been breached at the time, but they noted it was at the margin of its boundary and worsening.
Katherine Richardson, a professor at the Globe Institute at the University of Copenhagen in Denmark who led the 2023 study and was not involved in the new study, told Live Science that she was “not at all surprised” by the new findings.
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What causes ocean acidification?
Ocean acidification is mostly caused by the ocean absorbing CO2. The ocean takes up around 30% of CO2 in the atmosphere, so as human activities pump out CO2, they are forcing more of it into the oceans. CO2 dissolves in the ocean, creating carbonic acid and releasing hydrogen ions. Acidity levels are based on the number of hydrogen ions dissolved in water, so as the ocean absorbs more CO2, it becomes more acidic.
