In our race to limit global warming and meet net zero targets, reducing greenhouse gas emissions is crucial. However, it’s becoming clear that emissions reductions alone will not be sufficient to achieve the necessary climate goals. To bridge the gap, carbon dioxide removal (CDR) techniques are being explored, with a particular focus on ocean-based solutions. This article delves into the potential and challenges of using ocean-based CDR to combat climate change.
The Power of the Ocean:
The vastness of the ocean makes it an ideal candidate for carbon dioxide removal. With its extensive coverage of 70% of the Earth’s surface, the ocean has already absorbed approximately 25% of all human CO2 emissions since the industrial revolution. Enhancing the rate at which seawater incorporates CO2 can lead to significant drawdown of atmospheric CO2, potentially removing over a billion tonnes per year.
Ocean Alkalinity Enhancement (OAE):
One promising ocean-based CDR technique is Ocean Alkalinity Enhancement (OAE). This approach aims to increase the CO2 absorption potential of seawater by raising its pH. OAE offers advantages over other methods, including flexibility in generating alkalinity and the potential to counteract the negative effects of ocean acidification. However, the environmental impacts of enhanced alkalinity and the ability to monitor such effects in the open ocean are still not fully understood.
Marine Afforestation and Deposition:
Another technique involves increasing macroalgae production and burial. Seaweeds like Kelp and Sargassum absorb CO2 through photosynthesis and burying them in deep sea environments can prevent carbon from re-entering surface reservoirs. While seaweed cultivation is already a lucrative industry, further research is needed to understand the efficiency of sequestration and the environmental impact of deep-ocean carbon deposition.
Addressing Knowledge Gaps:
Various other ocean-based CDR techniques are being explored, but they require resolution of specific knowledge gaps before large-scale implementation can occur. Regulatory frameworks and codes of conduct are needed to minimize environmental risks and provide confidence to policymakers and investors. Collaborative research and engagement are essential to ensure the inclusive and responsible development of ocean-based CDR.
The SEAO2-CDR Project:
The Strategies for the Evaluation and Assessment Of Ocean-based Carbon Dioxide Removal (SEAO2-CDR) project brings together experts from multiple sectors to develop mechanisms, tools, and guidelines for responsible deployment of ocean-based CDR techniques. The project focuses on understanding system boundaries, establishing frameworks, and assessing system-level effects.
As we strive to meet global climate targets, a portfolio of CDR approaches, including ocean-based solutions, will be crucial. The ocean has the potential to play a significant role in carbon dioxide removal, but careful stewardship, collaboration, and further research are needed to ensure the safe, socially acceptable, and economically viable implementation of ocean-based CDR techniques.