Marine carbon dioxide removal: Our next ocean science, policy and governance frontier?

The world has crossed a critical climate threshold, with global average temperatures now a sustained reality above 1.5°C of warming. This reality shifts the focus from avoiding temperature overshoot to minimizing it and charting a course for climate restoration. The physics of climate change dictates that every fraction of human-linked CO2 emissions exacerbates risks, including more extreme weather, ice loss, and ocean acidification.

Reaching net-zero emissions, while crucial, is no longer sufficient on its own. To stabilize the climate system, deep cuts in CO2 emissions must be coupled with scaled-up carbon dioxide removal (CDR). While biological and land-based CDR approaches like reforestation and soil sequestration play a role, their limitations are becoming apparent. Finite land resources and the risk of impermanence, such as forest fires or carbon release from soils due to warming, present significant challenges.

The Intergovernmental Panel on Climate Change suggests that land-based CDR alone cannot achieve the gigatonne-scale removal needed. Therefore, attention is turning to the ocean, which plays a vital role in regulating the global climate. The ocean stores 98% of the planet's CO2, absorbs at least a quarter of annual human-made emissions, and captures over 90% of excess heat.

Marine carbon dioxide removal (mCDR) represents a new frontier in climate science, policy, and governance. It involves deliberate interventions to enhance the ocean's capacity to remove CO2 from the atmosphere. As World Oceans Day is celebrated on June 8, recognizing the ocean's extraordinary climate work is paramount. The development and implementation of mCDR strategies are becoming an urgent imperative to address the escalating climate crisis.