Knowledge dissemination report
Marine Carbon Dioxide Removal Technologies: Hopes and Threats
As part of the Paris Agreement, nations have committed to limiting global warming to 2°C or even 1.5°C. In most climate scenarios, carbon neutrality is reached via the rapid decarbonisation of economies, supplemented by large-scale CO₂ capture and storage. These approaches are referred to as carbon dioxide removal (CDR).
The ocean is a key ally in the fight against climate change, a massive “carbon pump” that captures 25% of human-released CO₂ emissions each year. This natural capacity relies on physical, chemical, and biological processes, all involving the transfer of carbon to the depths, either dissolved in the water or as organic matter.
Since the 1980s, scientists and companies have explored various technologies that could increase the ocean’s capacity to remove atmospheric CO₂ , for instance by dispersing large quantities of powdered alkaline minerals, which would, by chemical reaction, “neutralise” the CO₂ in the water. Still experimental and risky for marine ecosystems and communities, these technologies are called marine CDR (mCDR).
Today, the role that these technologies should play in global climate action is the subject of growing debate within the ocean and climate community. This debate is all the more complex because the field is recent and the scientific and governance stakes are numerous. While investments and experiments at sea are increasing, the public debate must be able to rely on robust and up-to-date knowledge.
As part of its scientific knowledge dissemination work, the Ocean & Climate Platform publishes Marine Carbon Dioxide Removal Technologies: Hopes and Threats. This report provides an overview of current knowledge, examines the opportunities and challenges associated with these technologies and highlights key scientific, environmental, social, and governance issues to inform public debate and policy-making.
Click below to discover the report!
As interest in mCDR technologies continues to grow, an assessment of the available evidence leads to several key observations. The report highlights five key messages:
- Scientific research remains essential to assess the effectiveness and impacts of mCDR. Current knowledge is limited, and experiments conducted to date have identified important risks to marine ecosystems. Field trials are still controversial, particularly because of uncertainties surrounding their long-term impacts and, in some cases, the sale of carbon credits.
- Investments in mCDR are growing rapidly, raising important governance and resource allocation challenges. Public and private funding can help advance scientific knowledge on mCDR and the ocean more broadly. However, questions remain about how resources should be balanced between support for mCDR, emissions reductions and climate change adaptation.
- Scientific uncertainties, socio-ecological risks and governance gaps limit the prospects for deployment. Except for blue carbon approaches, no mCDR technology has yet reached a level of maturity that would support safe, large-scale deployment within a robust governance framework.
- mCDR raises important ethical questions. The main risk is that the promise of future technological solutions could divert attention and resources away from emissions reduction efforts, while large-scale interventions in the Earth system could trigger unforeseen feedback loops.
- Rapid greenhouse gas emissions reductions must persist as the highest priority. Even under the most optimistic scenarios, mCDR can only play a limited complementary role alongside decarbonisation and cannot replace it.