The ocean and climate are inextricably linked. More than 90 percent of the extra heat from global warming has gone into the deep blue sea, with associated climate-driven changes reducing the productivity of fisheries and threatening more than 600 million people through sea-level rise. Yet the ocean offers opportunities: it could also be a source of solutions rather than just a victim of climate change.
One possibility is increasing the ocean’s uptake of carbon dioxide (CO2) from the atmosphere and storing it in the deep. Doing so on a large scale would help deliver the net zero goal of the Paris Climate Change Agreement. But considerations beyond just the financial commitments of research and development, costed at US$2.5 billion, will need to be taken into account.
Either biology or chemistry could be used to remove carbon dioxide from the atmosphere to store it in the ocean. The most straightforward approach is a ‘nature-based solution’, restoring the natural functions and processes already provided by our environment. Protecting marine ecosystems by ending overfishing and other conservation actions can reinstate the role of top predators in marine food webs, particularly those of the deep ocean — found in depths beyond 200 metres. The resulting increase in the abundance of larger organisms, such as fish and whales would transfer organic carbon from surface waters to deeper layers through faeces and deadfall, slowing the return of that carbon to the atmosphere.
