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.