Confirmed Special Sessions

Theme: Beyond tipping points – translating science to action

Actionable oceans: putting ocean acidification science and information into the right hands

Liz Perotti, NOAA Ocean Acidification Program
Liza Wright-Fairbanks, NOAA Ocean Acidification Program

The accelerating pace of ocean and coastal acidification (OA) necessitates the link from foundational monitoring and research to informed on-the-ground action. This session will explore ways to deliver OA decision support tools and services. Presenters will share innovative, effective, new or developing efforts for packaging and delivering data and information about ocean acidification and its impacts to people who need them the most. Presentations may showcase real-world impacts where these tools and services have supported coastal community resilience, industry sustainability, or policy development are of particular interest. The goal of this session is to bridge the gap between ocean monitoring, modeling and research outcomes to information in ways people can use.

Topics may include: next-generation forecasting and warning systems; visualization tools and data delivery platforms; species impact indicators or economic risk metrics; technical support and capacity-building programs; targeted outreach campaigns designed to integrate diverse knowledge systems.

The session's core audience are users and producers of products and services that address ocean acidification for people and economies.

Financing Ocean Futures: From OA Research to Coastal Safeguards

Anwesha Ghosh, Indian Institute of Science Education and Research Kol

Homer Pagkalinawan, Asian Development Bank

Scientific understanding of ocean acidification and coastal climate risks has advanced significantly. Investment decisions have not kept pace, leaving vulnerable communities without resources to adapt and climate funders without research in forms they can act on. This session examines how ocean acidification and coastal climate research can be translated into effective action by linking knowledge co-production with innovative finance, risk insurance, and emerging mitigation pathways.
The session will highlight integrated approaches that combine scientific evidence with indigenous, local, and practitioner knowledge to inform coastal adaptation, disaster risk reduction, and development planning. Topics include baseline assessments that pair economic valuation with vulnerability mapping to meet climate finance requirements; marine carbon dioxide removal (mCDR) as both mitigation and finance pathway; and blended finance instruments including non-parametric insurance for managing cascading hazards.
Through cases from deltas, estuaries, mangroves, and small island systems, the session explores how anticipatory governance and locally grounded innovation can strengthen resilience before critical thresholds are crossed. The aim is to advance discussion on what finance institutions need from researchers, and how study design can better anticipate the requirements of policy and funding pathways

From Data to Decisions: Operationalizing Interdisciplinary Ocean Acidification Knowledge

Alexandra Puritz, NOAA OAP/UCAR
Erica Ombres, NOAA OAP

Ocean and coastal acidification (OCA) threatens food security, economies, and ways of life because of its potential impacts on coastal ecosystems and societies. The NOAA Ocean Acidification Program (OAP) examines the ways in which coastal communities and industries are vulnerable to OCA and fosters research and partnerships that promote resiliency and adaptation. Through its portfolio of funded projects, OAP supports research that investigates the human dimensions of OCA through incorporation of the social sciences. Whether through co-development of research, interdisciplinary collaboration, or end-user engagement, these efforts produce actionable tools and techniques that can be utilized by coastal communities and decision-makers. This session will highlight innovative approaches to operationalizing knowledge and share insights on best practices, obstacles, and challenges.

Theme: Global-driven changes in biodiversity and ecosystem resilience

Buffer or Booster? When Primary Producers Mitigate or Amplify Ocean Acidification

Marco Munari, University of Padova
Sam Dupont, University of Gothenburg

Coastal ecosystems dominated by primary producers like macroalgae and seagrasses, are increasingly discussed as potential buffers against ocean acidification through photosynthetic CO₂ uptake and metabolic modification of local carbonate chemistry. At the same time, growing evidence highlights strong diel variability, night-time respiration, hydrodynamic constraints, and context dependency that may limit or even reverse this buffering effect. This session aims to address this ongoing scientific debate by bringing together contrasting perspectives, empirical evidence, and conceptual frameworks. We invite contributions spanning laboratory experiments, field observations, natural analogues (e.g. CO₂ vents), mesocosm studies, and modelling approaches that assess when, where, and at which scales primary producers mitigate, or fail, acidification impacts on marine organisms and communities. Emphasis will be placed on linking biological responses and ecological interactions, and implications for ecosystem resilience, restoration, and management under future climate scenarios. By explicitly confronting divergent results and interpretations, the session seeks to move beyond simplistic narratives and toward a more nuanced, mechanistic understanding.

Ocean acidification in the Mediterranean Sea: variability, vulnerability, and pathways in a high-CO₂, multi-stress basin

Iris E. Hendriks, CSIC
Abed El Rahman Hassoun, GEOMAR

The Mediterranean Sea is a semi-enclosed, human-dominated basin and a recognized climate change hotspot, making it exceptionally sensitive to ocean acidification (OA) and its interaction with other stressors. Rapid warming, strong spatial and temporal variability in carbonate chemistry, eutrophication, deoxygenation, and intense coastal pressures shape complex ecosystem responses to rising CO₂ across the region.

This session, led by the members of the GOA-ON Mediterranean Hub, invites contributions that advance understanding of OA in the Mediterranean through observations, experiments, and modeling. We encourage studies using long-term monitoring, autonomous and coastal observing systems, and natural CO₂ analogues (e.g. volcanic seeps) to resolve drivers of variability and biological sensitivity.

Presentations addressing impacts on pelagic and benthic ecosystems, habitats of high ecological and socio-economic value (such as seagrass meadows, coralligenous communities, fisheries, and aquaculture), and the role of multiple stressors in shaping vulnerability and resilience are particularly welcome. Contributions exploring regionally relevant mitigation, adaptation, and management strategies are encouraged. By integrating observations, predictive tools, and stakeholder-relevant knowledge, this session aims to strengthen Mediterranean OA coordination and connect basin-scale insights to global high-CO₂ ocean research.

Theme: Multiple stressors' effects on marine organisms

Assessing high-CO₂ and multi-stressor effects on aquatic organisms using natural laboratories of climate change

Ivan Nagelkerken, Adelaide University, Australia
Riccardo Rodolfo-Metalpa, IRD, New Caledonia
Sylvain Agostini, IRD, New Caledonia

Marine, estuarine, and freshwater organisms contribute significantly to global biodiversity and are strong mediators of processes that maintain ecosystem functioning and provide critical ecosystem services. However, climate change stressors like ocean warming, ocean acidification, and hypoxic zones, are set to reshuffle life on Earth and alter ecological processes that underpin the biodiversity, productivity, and resilience of aquatic ecosystems. Most research has focussed on the effects of warming, whilst the effects of other stressors, and particularly that of combined stressors remain understudied. Some multi-stressor experiments have been performed in laboratory studies, but these cannot full incorporate the ecological complexity of natural systems. Natural laboratories of climate change – such as volcanic CO₂ vents, warming hotspots, upwelling areas, semi-enclosed lagoons – provide opportunities to test the effects of climate (multi-)stressors on organisms in their natural environment. Here, we invite talks that use natural laboratories of climate change to study high-CO₂ and multi-stressor effects on aquatic organisms. Studies can focus on ecological traits, behaviour, physiology, genetic adaption, community change, biodiversity, species range extensions, modelling approaches, and meta-analysis. These talks will contribute to useful insights on how we can better assess the broader effects of climate change on aquatic organisms under more natural conditions.

Ocean acidification multiple stressor effects on North American species

Helen Gurney-Smith, Fisheries and Oceans Canada
Richard A. Feely, Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington, USA and Paciﬁc Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, USA
Cecilia Chapa Balcorta, Instituto de Recursos, Universidad del Mar. Puerto Ángel, Oaxaca, México

Marine species are experiencing the effects of ocean acidification alongside other climate change and anthropogenic impacts, such as warming, hypoxia, eutrophication and pollution. Therefore single stressor studies may not reveal the complexity of species responses to environmental change. This session will explore the impacts of multiple stressor effects, including ocean acidification, on marine species and ecosystems of North America. Presentations in this session can include experimental or in situ field research, modelling or vulnerability assessments, synthesis studies, and both coastal and open ocean acidification biological observations. Studies that include linkages to socioeconomic considerations or decision-making for marine species management (both observed and projected) will also be welcome, as are those that examine species local adaptation or resilience.The presentations can also address key gaps, practical challenges, and how OA and other stressor communities can work together to support future ocean-based integrated studies.

Theme: Ocean-based solutions

Addressing Coastal Acidification and Enhancing Carbon Sinks through Coordinated Management of Wastewater, Nutrients, and Ecosystems

Chuanlun Zhang, Southern University of Science and Technology
Lina Hansson, International Atomic Energy Agency (IAEA)

Coastal acidification is driven primarily by anthropogenic CO₂ emissions and intensified by localized stressors such as eutrophication and low-pH wastewater discharge, which poses a serious threat to marine biodiversity and compromises the ocean's capacity to act as a carbon sink. In response, this session will explore three integrated climate mitigation scenarios:

Coupling wastewater treatment with ocean alkalinity enhancement to leverage engineered microbial processes for long-term inorganic carbon storage.
Advancing land-sea nutrient management to reduce eutrophication-driven acidification and strengthen coastal blue carbon ecosystems.
Implementing integrated sea-farming systems that balance nutrient supply, CO₂ sequestration, and the export of recalcitrant dissolved organic matter.

This session aims to foster interdisciplinary collaboration by highlighting carbon-stabilizing mechanisms across aquatic-terrestrial continua. We also advocate for unified observational frameworks and standardized metrics to support actionable strategies aimed at achieving ocean negative carbon emissions.

Alkalinity cycling in a changing ocean

Astrid Hylén, CEREGE, France
Sebastiaan van de Velde, University of Otago, New Zealand

Alkalinity plays a central role in regulating Earth’s climate by enhancing seawater’s capacity to store CO₂. Although significant attention has recently focused on ocean alkalinity enhancement as a carbon dioxide removal (CDR) strategy, the natural cycling of alkalinity in the ocean and how this cycle responds to human pressures, remain poorly understood. Research highlights the importance of vegetated coastal ecosystems and benthic fauna for alkalinity production, while other studies demonstrate that human disturbances, including ocean acidification, ocean alkalinity enhancement, and trawling, can directly alter natural alkalinity sources.

This session invites contributions that investigate alkalinity cycling across marine environments. We seek to foster a complete understanding of alkalinity dynamics in a changing ocean, spanning mechanistic studies, ecosystem-scale assessments, and implications for ocean acidification and carbon management. Given the session’s broad relevance, we hope to foster dialogue among marine carbon cycle researchers, members of coastal communities, organisations working with CDR, and policymakers.

Global Ocean Acidification Observing Network Perspectives on Ocean Solutions

Helen Findlay, Plymouth Marine Laboratory
Richard A. Feely, NOAA Pacific Marine Environmental Laboratory

Marine carbon dioxide removal (mCDR) is increasingly being explored as a complement to emissions reductions, with growing interest in its potential to mitigate ocean acidification (OA) as well as excessive atmospheric CO₂. This special session will showcase ongoing and emerging mCDR and OA mitigation initiatives, including observational, experimental, and modelling efforts, and consider how these activities align with Global Ocean Acidification Observing Network (GOA-ON) priorities: improving understanding of carbonate system dynamics, ecosystem responses, and the data and knowledge exchange needed to support robust monitoring, reporting and verification. Speakers should reflect on lessons learned from OA research that are directly relevant for mCDR, such as baseline characterization, observing system design, biological indicators, scaling from local interventions to broader impacts on the ocean carbon budget, and capacity building. The session will conclude with a moderated panel discussion focused on cross-cutting insights, key gaps, and practical challenges, and on how OA and mCDR communities can work together to support safe, effective and equitable ocean-based solutions in a high-CO₂ world.

Intended audience: scientists working on ocean acidification, carbon cycling, mCDR, marine ecosystems and observations; early-career researchers; and stakeholders interested in ocean-based climate solutions.

Understanding ocean-based climate solutions: Ecological implications, monitoring needs, and financing pathways

Svenja Halfter, Earth Sciences New Zealand
Nathalie Hilmi, Centre Scientifique De Monaco
Peter Busumprah, Ocean Rock Base and Africa Ocean Alliance ( African Ocean Biodiversity Atlas)
Abed El Rahman Hassoun, GEOMAR Helmholtz Centre for Ocean Research Kiel
Linn Hoffmann, University of Otago, New Zealand

Ocean-based carbon removal is critical for reducing greenhouse gas concentrations, protecting biodiversity, and enhancing coastal resilience, while also generating new economic opportunities. In this session, we invite contributions to three themes: (i) Blue carbon ecosystems, their ecological and biogeochemical processes, and digital tools that improve the valuation, mapping, and monitoring of marine habitats. (ii) Emerging mCDR methods, such as ocean alkalinity enhancement, nutrient fertilisation, and biomass sinking, with pilot studies on carbon removal efficiency, environmental impacts, and the development of credible MRV frameworks aligned with carbon markets. (iii) Financial and governance mechanisms of scaling ocean-based solutions responsibly. Contributions are encouraged on blue bonds, blended finance, insurance instruments, payment for ecosystem services, and public–private partnerships, as well as analyses of investment readiness, regulatory frameworks, and socio-economic co-benefits. The session aims to identify science-based and bankable pathways that support the UN Decade of Ocean Science and advance climate-resilient, inclusive ocean stewardship.

Theme: Technological advances in marine climate change research

Charting the Future: Emerging Technologies for Ocean Acidification Monitoring

Kaity Goldsmith, National Oceanic and Atmospheric Administration Ocean Acidification Program
Liza Wright-Fairbanks, National Oceanic and Atmospheric Administration Ocean Acidification Program

This session invites researchers, engineers, and managers to explore the cutting edge of ocean acidification (OA) monitoring. Presentations will highlight the development and deployment of novel sensors, emerging technologies like autonomous systems and satellite-based monitoring, and innovative methods for data processing and modeling that enhance our understanding of OA impacts. Topics include, but are not limited to, the advancement of low-cost sensors, high-resolution sensors, integrated observation networks, and the application of machine learning for forecasting and risk assessment. The goal of this session is to highlight solutions that improve our capacity for data collection, enable a global, standardized observation framework, and inform effective management and adaptation strategies in estuarine, coastal, and open ocean ecosystems. Join us to chart the future of OA observation.

New approaches for quantifying variability and human impacts on ocean biogeochemistry from sparse observational data

Brendan Carter, U. Washington-CICOES/NOAA-PMEL
Leticia Barbero, U. Miami-CIMAS/NOAA-AOML

Monitoring ocean variability and human impacts is essential, but it is also challenging and expensive. It is therefore often necessary to use innovative methods to derive needed information from spatially- or temporally-sparse measurements. Objectively mapping measurements is a common example, but oceanography is now benefitting from novel applications involving machine learning, data assimilation, transport matrices, varied inverse models, and other approaches. In addition, the rapid expansion of autonomous platforms and remote sensing has produced a wealth of new observational data, which when coupled with these novel techniques for gap-filling in space and time, offers unprecedented opportunities for advancing understanding of the ocean.

This session provides a place for researchers to showcase insights gained from employing and testing these new approaches. The session is especially interested in insights related to identifying meaningful variability or human impacts in the ocean. The timescales and topics of interest can range broadly from long-term trends in ocean heat, carbon, freshwater, and dissolved gas distributions, to event-scale phenomena such as the impacts of marine heatwaves or storms on circulation, fluxes, and ocean acidification. Reconstructions of known model fields intended to quantify uncertainties in such reconstructions are also explicitly welcomed.

Theme: The modulating role of time – from short-term variability to evolution

Ocean Deoxygenation: A Twin Threat to Ocean Health in a High CO₂ World

Ariel Pezner, University of Technology Sydney

Driven by warming-induced stratification, reductions in oxygen solubility, and increased respiration rates, ocean deoxygenation is a powerful and significant threat to marine systems globally. The ocean has lost nearly 3% of its oxygen content since the 1970s, with 59-80% of the ocean projected to experience the impacts of deoxygenation by 2031. Deoxygenation affects all areas of the ocean, from the expansion of oxygen minimum zones to growing coastal hypoxic regions. Along coastal margins, interactions with local anthropogenic drivers such as eutrophication can further exacerbate oxygen loss resulting in dead zones. Given that oxygen is required for the functioning of most life on Earth, the ecological impacts of global ocean oxygen loss are significant, with evidence supporting this from coral reefs to polar seas to temperate estuaries and more.

This session will focus on studies that examine how ocean deoxygenation and oxygen loss affect marine systems. Topics might include the effects of oxygen loss on organisms, trends in oxygen loss, drivers and consequences of oxygen loss on ecosystem or global scales, or interactions between deoxygenation and other global ocean stressors such as warming and acidification. We encourage submissions from a wide range of perspectives, from molecular to ecosystem, and across spatial scales from local to global, as well as submissions focusing on interventions, management, and regulation of deoxygenation globally.

Theme: Working across knowledge systems in a high-CO₂ world

Rebuilding coastal ecosystems through transformative change: Coastal people and a changing world

Gaya Gnanalingam, University of Otago
Nam Chand, University of Otago
Ohad Peleg, Victoria University of Wellington

This special session showcases research on socio-ecological aspects of coastal systems conducted globally in partnership with coastal and indigenous communities. This session supports submissions of abstracts from researchers focused on understanding how marine climate change, including ocean acidification, and their potential interactions with local drivers of change impact marine ecosystems and the communities they support, and how we can develop solutions to solve or mitigate some of these impacts. Thus, we would favour submissions that focus on research that has been co-designed or led by coastal and/or indigenous communities and has real-world implications for them and their stewardship (kaitiakitanga) of their marine ecosystems.

The River-Ocean Nexus: Freshwater Acidification in a High-CO₂ World

Adam Hartland, Lincoln Agritech

While ocean acidification (OA) has been a central focus of climate research for decades, the impact of rising atmospheric CO₂ on freshwater ecosystems remains critically under-explored. River corridors serve as the ultimate nexus between the atmosphere, land, and sea, yet our understanding of freshwater acidification lags behind its marine counterpart. This session will present findings from the Emerging Climatic Pressures MBIE programme, focusing on how changing CO₂ exchange at the air-water interface and retention in rivers is driving fundamental shifts in freshwater chemistry and ecology. We will explore the mechanisms behind declining pH in rivers and lakes, the resulting impacts on algal community succession and primary productivity, and the risks to keystone freshwater species (such as kākahi/freshwater mussels). By bridging the gap between freshwater and marine carbonate chemistry, this session invites a mountains-to-the-sea perspective on the high-CO₂ world, highlighting how inland water quality trends may deviate from traditional nutrient-based models to define new climatic pressures on both freshwater and coastal ecosystems.

Understanding a high-CO₂ Arctic: observations, modeling, impacts, and emerging approaches across scientific and Indigenous knowledge systems

Kumiko Azetsu-Scott, Bedford Institute of Oceanography, Fisheries and Oceans, Canada

Agneta Fransson, Norwegian Polar Institute

Claudine Hauri, University of Alaska Fairbanks, USA

The Arctic Ocean is undergoing rapid transformation, as ocean acidification, warming, disappearing sea ice, coastal erosion, and accelerated freshwater input from glacial melt and river runoff driving unprecedented changes in ecosystems. This session highlights research exploring these changes and its ecological impacts in this sensitive region. Presentations featuring new technologies for monitoring carbonate chemistry and biological responses, as well as approaches to evaluate mitigation strategies at local and regional scales, are encouraged. The use of multiple knowledge systems and co-development of observations with local communities, ensuring that research is culturally relevant and actionable, are particularly welcomed. By linking long-term and wide-ranging observational datasets with predictive modeling and community-engaged research, the session aims to advance understanding of the coupled physical, chemical, and biological processes shaping the Arctic Ocean under high CO₂ conditions. Participants are invited to discuss strategies to sustain Arctic ecosystems and inform science-based policy in this rapidly changing environment.

Intended audience: Observational oceanographers, modelers, biologists, community members, and policy makers.