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.