In this special video edition of Plan Sea, host Anna Madlener and Carbon to Sea’s Senior Manager for Communications, Danny Gawlowski, record from the Ocean Sciences Meeting (OSM) in Glasgow, Scotland. They sit down with members of the COMPASS mCDR Communication Leaders program — Dr. Abigale Wyatt, an ocean modeler from [C]Worthy, Dr. Mariam Swaleh, who leads the Ocean Climate Innovation Hub in Kenya, and Dr. Kohen Bauer, science director at Ocean Networks Canada — to explore what makes science communication effective, where it falls short, and lessons learned for communicating about mCDR research.

The Communication Leaders program, sponsored in part by Carbon to Sea, aims to support mCDR experts with the skills to engage with policymakers, media, funders, and local communities, helping them to foster responsible dialogue across the field. Drs. Wyatt, Swaleh, and Bauer shared how — through a series of virtual trainings and a culminating two-day, in-person workshop — participants collaborated on exercises to clarify their audience, utilize accessible language, and practice realistic scenarios through role-playing stakeholder engagements. These exercises helped build confidence, expose gaps in existing community engagement practices, and approach forums like OSM with a clearer communication lens.

Effective science communication is essential to bridge mCDR researchers and their scientific findings with peers in other fields, decision-makers who influence research permitting and funding, and communities where research is happening. Dr. Bauer framed it as a foundational skill operating as the basis for collaboration and learning. A chemist by trade, Dr. Swaleh emphasized the limits of highly technical jargon and noted that accessible language is key to reaching your audience. Dr. Wyatt first saw the benefits from the personal experience of navigating conversations with climate skeptical family members.

Our guests also discuss challenges in communicating across cultures, different types of stakeholders, highly politicized environments, language barriers, and different levels of scientific literacy. Dr. Swaleh shares part of this difficulty in the way “common” phrases, such as climate change, can experience difficulties in the way they are translated. She recounts how in Kiswahili, the notion of climate change moved from discussing the weather to “patterns of the country.” In this way effective communication requires slowing down, listening first, and building a shared understanding together.

Thank you to everyone who shared their time to join us in-person at OSM in Glasgow, it was an incredibly insightful opportunity to connect, reflect, and learn alongside the field’s global community. To learn more about the COMPASS mCDR Communications Leaders program and the insights Drs. Wyatt, Swaleh, and Bauer shared about how they approach communications across different audiences and contexts, watch or listen to the episode through your preferred podcast service and find the entire series here.

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative and the American University Institute for Responsible Carbon Removal.

ACRONYMS/CONCEPTS:

• DOR: Direct Ocean Removal
• EVs: Electric Vehicles
• mCDR: Marine Carbon Dioxide Removal
• MRV: Monitoring, Reporting, and Verificati

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative & the American University Institute for Responsible Carbon Removal.

In this edition of Plan Sea, hosts Anna Madlener and Wil Burns are joined by Frank Rattey and Dr. Thorben Amann of Planeteers — a Hamburg-based carbon removal startup researching alkalinity-based carbon dioxide removal (CDR) approaches — to discuss the science behind their closed-system pathway, their first field tests, and the national regulations guiding ocean-climate research.

Dr. Thorben Amann is the Research and Development Lead at Planeteers and a geochemical CDR specialist. In this episode, Thorben explains how Planeteers’ closed-system approach differs from other ocean alkalinity enhancement (OAE) strategies. Rather than dissolving alkalinity directly in the ocean to drive carbon dioxide uptake, Planeteers combines carbon dioxide from point sources and alkaline feedstock in a closed reactor where it forms stable alkalinity and is then discharged into rivers or oceans.

Thorben walks through the chemistry behind this process and explains how this approach offers advantages for monitoring, reporting, and verification (MRV). Because inputs and outputs are in a controlled reactor, Thorben asserts it’s easier to conduct monitoring and initial reporting. At the same time, Thorben highlights a key challenge for the field: ensuring the stability of the alkalinity after discharge. For carbon storage to be durable, he explains that the alkalinity must remain equilibrated and stable.

Frank Rattey, Co-Founder and Managing Director of Planeteers, then discusses Project Helix, Planeteers’ first field deployment located at a wastewater treatment plant in Hetlingen, Germany. Validated through the registry Isometric, this first-of-its-kind research project discharges alkalinity-enriched water into the treatment plant’s aquatic system to provide long-term carbon storage.

Noting that Germany is the only country in the world that has translated the London Convention London Protocol into national law, Frank also offers insight into how Planeteers is operating under Germany’s regulatory environment. In order to conduct their field research safely and responsibly, Planeteers cooperates with wastewater treatment plants, construction permits, and regional water authorities in the country.

To learn more about Planeteers’ closed-system, alkalinity-based CDR approach, listen to the episode above, subscribe with your favorite podcast service, or find the entire series here.

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative and the American University Institute for Responsible Carbon Removal.

ACRONYMS/CONCEPTS:

• MRV: monitoring, reporting, verification
• CO2: carbon dioxide
• R&D: research and development
• CDR: carbon dioxide removal
• OAE: ocean alkalinity enhancement
• LCA: life cycle analysis
• EU: European Union
• London Convention (LC): Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1972
• London Protocol: 1996 Protocol to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, 1972

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative & the American University Institute for Responsible Carbon Removal.

In this episode of Plan Sea, hosts Anna Madlener and Wil Burns sit down with Professor Dr. Alexander Proelss, Chair in the International Law of the Sea and International Environmental Law, Public International Law, and Public Law at the University of Hamburg, to discuss the current state and recent developments of international legal frameworks regulating ocean-based carbon dioxide removal (oCDR). Alexander discusses the need for international law to ensure responsible regulation of oCDR, and offers insight into the relevant international agreements for oCDR research.

Alexander joins Anna and Wil to help make sense of the existing international landscape, as well as what they mean for the development and regulation of ocean-climate research. He explains that international law is essential to ensuring responsible development of oCDR — and yet there is no single international treaty governing it.

He explains how the 1972 London Convention and the 1996 London Protocol (LC/LP) — originally designed to regulate the dumping of waste but later adapted to govern marine geoengineering — is the most relevant international framework to date, guiding the ocean-climate field. However, it has had slow progress in listing and regulating oCDR methods such as ocean alkalinity enhancement (OAE). Alexander discusses how today, the LC/LP interacts with the Paris agreement, the UN Convention on the Law of the Sea (UNCLOS), and the 2023 Biodiversity Beyond National Jurisdiction Agreement (BBNJ). He also offers insight into how new legislation in Germany could make the country a "front runner" by implementing the LC/LP, permitting scientific research of several oCDR approaches and marking a significant shift from its previously highly precautionary stance.

Alexander also discusses the tendency of international agreements to limit oCDR activities to scientific research and how regulation must balance risk mitigation with harnessing the benefits of oCDR. Looking ahead, he explains how a clear framework for governing commercial activity could help proven oCDR methods grow responsibly.

To learn more about the latest state of international legal frameworks for oCDR, listen to the episode above, subscribe with your favorite podcast service, or find the entire series here.

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative and the American University Institute for Responsible Carbon Removal.

ACRONYMS/CONCEPTS:

• London Convention (LC): Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1972
• London Protocol: 1996 Protocol to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, 1972
• OAE: ocean alkalinity enhancement
• oCDR: ocean carbon dioxide removal
• CDR: carbon dioxide removal
• UNCLOS: UN Convention on the Law of the Sea
• EEZ: exclusive economic zones
• BBNJ: Biodiversity Beyond National Jurisdiction Agreement of 2023
• ICJ: International Court of Justice

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative & the American University Institute for Responsible Carbon Removal.

In this episode, hosts Anna Madlener and Wil Burns are joined by Dr. Grace Andrews and Kristi Weighman of Hourglass Climate — a leading nonprofit researching ocean-based carbon dioxide removal (oCDR, also known as mCDR ) methods like ocean alkalinity enhancement (OAE) — to discuss the launch of the Framework for Ecotoxicological Modeling of mCDR (FEMM). This project explores how ecotoxicological modeling and existing statistical approaches can be applied to OAE and oCDR projects, improving the field’s understanding of these potential climate solutions’ environmental risks. Dr. Andrews and Weighman offer insight into their process building and receiving feedback on FEMM, the framework’s regulatory potential, and how FEMM can be applied across oCDR research.

Dr. Grace Andrews, Founder and Executive Director of Hourglass Climate, now in her tenth year of working in the CDR field, last appeared on Plan Sea in 2024 to discuss Hourglass’ role in advancing monitoring, verification, and reporting (MRV) for OAE. In this episode, she’s joined by Kristi Weighman, an Hourglass scientist with expertise in ecotoxicology. Together, Grace and Kristi discuss how they recognized a critical gap in oCDR research — the lack of tools to monitor and model environmental risk — and developed a first-of-its-kind framework to fill that gap.

Grace explains how our understanding of oCDR’s environmental safety has lagged behind scientific developments in the field. In order to advance these projects in a responsible way, Grace believes that the field needs more rigorous, standardized approaches for modeling and measuring environmental risks.

FEMM aims to address this gap through combining established statistical approaches with emerging modeling techniques, borrowing existing protocols from the ecotoxicology space and applying them to the nuances of oCDR. The framework begins with a screening-level assessment that uses highly conservative assumptions to determine whether a project’s risks can be ruled out. Projects with identified risk may need to redesign aspects of their approach before moving on to more realistic assessment tools. The modeling relies on species sensitivity distributions (SSD) and calculations based on predicted environmental concentration (PEC) and predicted no effect concentration (PNEC). While this SSD approach has been applied to other environmental stressors, this is the first time it’s been applied to oCDR. Grace and Kristi also highlight examples of specific mCDR stressors and conditions where data may be too sparse to fully apply this approach today, and outline research priorities that will enable a standardized approach for these over time.

Looking ahead, Grace and Kristi share their optimism about FEMM’s utility for researchers and broader oCDR stakeholders. They hope the tool will enable users to identify potential risk in their proposed projects, integrate cross-disciplinary data, and foster greater regulatory dialogue.

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative and the American University Institute for Responsible Carbon Removal.

To listen to Dr. Grace Andrew’s first Plan Sea podcast appearance,

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative & the American University Institute for Responsible Carbon Removal.

In this episode of Plan Sea, hosts Anna Madlener and Wil Burns sit down with Stefano Capello, CEO and founder of Limenet — an Italian startup focused on limestone-based ocean alkalinity enhancement (OAE) and net-zero lime production — and Sara Groppelli, a PhD researcher at the University of Milano-Bicocca studying the impact of Limenet’s approach on phytoplankton communities. Stefano discusses Limenet's journey from theoretical experiments in his grandmother’s garage to a pilot plant in Italy that is navigating key, real-world questions around cost efficiency and scale, environmental safety, permits and regulatory pathways, and community engagement.

Stefano recounts Limenet’s unconventional beginnings, which started as a prototype research project in his grandmother’s garage, and now operates a pilot facility in southern Italy. Since 2023, Limenet has focused on developing an OAE approach that pre-dissolves limestone alkalinity in reactors and pre-equilibrates seawater with atmospheric CO2 before releasing it back into the ocean. This closed-system approach is designed to reduce scientific uncertainty in alkalinity additions and to minimize risks such as particle sedimentation or unwanted precipitation.

Now, Limenet is focused on addressing key questions about how its OAE approach could be scaled. Stefano shares updates on the company’s journey to reduce the energy intensity of its lime production and the associated costs, and how the team is engaging communities and policymakers as they navigate Italy’s regulatory landscape.

The ecological safety of Limenet’s OAE approach are also important to thoroughly evaluate, and Sara shares updates from her research on potential impacts on phytoplankton communities. Sara highlights how controlled alkalinity enhancement appears to have limited ecological disruption when carefully designed. However, long-term and site-specific studies are important to thoroughly understand potential impacts and also co-benefits, such as potential buffering against ocean acidification.

Listen to the full episode to learn more about Limenet’s growth and how the team is approaching important questions around environmental safety, cost and scale, monitoring and evaluation, community engagement, permitting pathways, and more.

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative and the American University Institute for Responsible Carbon Removal. Subscribe on your preferred podcast platform and find the entire series here.

ACRONYMS/CONCEPTS:

• CDR: carbon dioxide removal
• ISO: International Organization for Standardization
• MRV: monitoring, reporting, and verification
• OAE: ocean alkalinity enhancement

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative & the American University Institute for Responsible Carbon Removal.

In this episode of Plan Sea, hosts Anna Madlener and Wil Burns sit down with researchers Dr. Leila Kittu, Dr. Giulia Faucher, and Dr. Charly Moras to discuss the latest updates from the Ocean Alk-Align consortium’s exploration of ocean alkalinity enhancement’s (OAE) environmental safety and efficiency. Representing expertise from the GEOMAR Helmholtz Centre for Ocean Research and the University of Hamburg, Leila, Giulia, and Charly join Anna and Wil to share valuable insights on what’s needed for monitoring, reporting, and verification (MRV) and environmental safety assessments.

Ocean Alk-Align is dedicated to evaluating the efficacy and durability of carbon uptake and storage; environmental safety and potential co-benefits; and MRV requirements of various OAE approaches. Leila, Giulia, and Charly discuss how understanding OAE’s efficiency — commonly measured by how many tons of carbon dioxide is removed per ton of material added to the ocean — is incredibly nuanced. The group’s research suggests we must also consider factors such as dilution, sinking, and horizontal mixing when discussing the efficiency of various OAE approaches in different real-world settings.

To evaluate OAE’s environmental safety and better understand how scientists can protect living ecosystems without sacrificing efficiency, Leila, Giulia, and Charly discuss mesocosm experiments that were conducted. The team gradually included multiple species of plankton to identify how biological life responds to seawater changes. Mesocosm research is advantageous for breaking down complex problems into manageable pieces — but is limited in terms of scale, duration, and ability to capture higher trophic levels.

Looking ahead, the group called for more robust frameworks for environmental safety assessment and thresholds as OAE projects move towards field research. The group argues that the broader benefit of carbon removal seeks to outweigh the potential risk of interfering in delicate ocean environments, and requires careful consideration and standardization across these frameworks. Ocean Alk-Align’s work aims to provide a scientifically-rigorous, informed pathway to weighing this “give and take” decision.

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative and the American University Institute for Responsible Carbon Removal.

ACRONYMS/CONCEPTS:

• OAE: ocean alkalinity enhancement
• MRV: monitoring, reporting, and verification
• mCDR: marine carbon dioxide removal
• OAE-PIIP: Ocean Alkalinity Enhancement Pelagic Impact Intercomparison Project

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative & the American University Institute for Responsible Carbon Removal.

In this episode of Plan Sea, hosts Anna Madlener and Wil Burns sit down with Dr. Phil Renforth and Dr. Mijndert Van der Spek of Heriot-Watt University to unpack their newly published, harmonized framework for evaluating the viability of ocean alkalinity enhancement (OAE) pathways. Moving beyond lab-scale assumptions, their approach integrates techno-economic analysis (TEA) and lifecycle assessment (LCA) to allow the exploration of 54 known OAE variations and how they perform under future, decarbonized energy scenarios. The conversation highlights why real-world data, a cleaner energy grid, and feasibility assessments are important for determining which OAE pathways will deliver results in global scale carbon removal.

With any emerging solution, both feasibility and cost must be effectively evaluated. Renforth and Van der Spek combine two essential lenses – techno-economic analysis (TEA) and lifecycle assessment (LCA) – to build a comprehensive picture of OAE’s real potential. TEA determines if a pathway is economically viable and scalable, while LCA screens for its full environmental impacts, not only if it is net-negative, but also whether it engages in “burden shifting,” or solving one problem while creating another. Operating far beyond “carbon balancing,” LCA works across a range of categories, from greenhouse gas emissions to terrestrial and marine acidification, resource use, and pollution. Together, the two tools are meant to provide a level of quantification for decision-makers investigating the viability of any CDR approach.

In looking at the framework, Dr. Renforth and Dr. Van der Spek began by introducing the framework’s structure through a case study of BPMD and its functionality as OAE technology. Rather than offering predictions, the framework helps to show how different technologies perform under current assumptions. This means the framework should not be viewed as forecasting long-term outcomes on its own, but instead as a tool to see how each pathway changes.

While these tools are powerful, they are incomplete and alongside rigorous research into the broader social, regulatory, and ethical implications of each potential pathway. For example, LCA aims to measure global stressors by normalizing impacts, but it does not have the ability to detect localized effects. This highlights that any comparison drawn from the framework must be paired with site-specific environmental assessments. Together, these layers of analysis provide a more realistic understanding of where OAE pathways may be within reach.

Join us as we dive deeper into this framework and how it aims to spur further evaluation and innovation in OAE by listening to the episode above! Subscribe on your preferred podcast platform and find the entire series here.

ACRONYMS / CONCEPTS:

• CDR: Carbon Dioxide Removal
• OAE: ocean alkalinity enhancement
• TEA: Techno-Economic Analysis
• LCA: Lifecycle Assessment
• BPMED: Bipolar Membrane Electrodialysis

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative & the American University Institute for Responsible Carbon Removal.

In this episode of Plan Sea, hosts Anna Madlener and Wil Burns dive deep into the new Biogeosciences special issue focused on the environmental safety of ocean alkalinity enhancement (OAE). This episode’s guests are Dr.Lydia Kapsenberg and Dr. Tyler Cyronak who helped edit the special issue. Compiling more than 20 studies, the special issue serves as a “one-stop shop” of the latest peer-reviewed science on the environmental safety of OAE — ranging from responses of micro algae and corals, to the influence of biogeochemical cycling and trace metals. Tune in as we unpack what insights these studies collectively suggest and discuss what it means for next steps in environmental safety research for OAE.

The volume of OAE research has grown dramatically in recent years — increasing four-fold over the last five years. The Biogeosciences special issue shines a light on this rapidly evolving landscape and offers a tool for researchers, funders, regulators, and other partners to access centralized information on potential ecological risks, environmental monitoring standards, and feedstock safety related to multiple OAE approaches.

Throughout the discussion, many themes arise, including the question: How important is it to understand both system-wide patterns and local ecological realities? Lydia and Tyler highlight that while the Biogeosciences studies suggest that many phytoplankton species appear to be resilient under expected OAE conditions, local species and ecological contexts must still be factored into any field research design. This is where researchers have an important responsibility to meaningfully engage with communities on what matters most for their local marine ecosystems and align planned environmental monitoring efforts accordingly.

For researchers, policymakers, and communities assessing OAE’s environmental safety as a potential climate solution, the Biogeosciences special issue offers a crucial early evidence base and a clearer picture of what questions come next.

As mentioned during the episode, Carbon to Sea’s Environmental Impact Monitoring Framework is now available for public review and comment here, through December 12th. Carbon to Sea and the Prince Albert II of Monaco Foundation are also currently soliciting proposals for scientific research on the safety of OAE on commercially and culturally valued marine species. You can view the full funding opportunity and submit a proposal by January 16, 2026.

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative and the American University Institute for Responsible Carbon Removal.


ACRONYMS / CONCEPTS:

• CDR: Carbon Dioxide Removal
• EPA: Environmental Protection Agency
• MRV: monitoring, reporting, and verification
• OAE: ocean alkalinity enhancement
• OAEPIIP: Ocean Alkalinity Enhancement Pelagic Impact Intercomparison Project

Plan Sea is a semi-weekly podcast exploring ocean-based climate solutions, brought to you by the Carbon to Sea Initiative & the American University Institute for Responsible Carbon Removal.