We’re past the point of no return on climate emissions — it’s time we turn to carbon removal

Covering 70 percent of the planet, the ocean has borne the brunt of damage caused by our disrupted climate — absorbing more than 90 percent of the excess heat trapped on the planet, and 26 percent of all civilization’s carbon dioxide pollution.  

While this has shielded humanity and terrestrial ecosystems, the effects in the ocean are alarming: unprecedented warming, acidification, deoxygenation, and a host of related changes that further undermine the stability of our climate. Decreasing emissions must remain an urgent priority of the global community, but the problem is this: Even if we stopped all emissions today, existing carbon pollution in the air will continue to warm the planet to devastating levels. 

New tools are urgently needed to restore the climate and repair the ocean, particularly carbon dioxide removal, including potential ocean-based pathways. 

The United Nations Intergovernmental Panel on Climate Change has made clear that large-scale carbon dioxide removal will be needed this century to hold temperatures to a 1.5 degrees Celsius increase — the goal set out in the Paris Agreement. And if we aspire to ultimately re-cool the planet, carbon dioxide removal is the only tool that can remove the legacy carbon dioxide pollution that otherwise will stay in the atmosphere for hundreds or thousands of years. 

Carbon dioxide removal refers to a variety of natural and engineered methods to remove carbon dioxide from the atmosphere and the upper layer of the ocean. These techniques range from tree planting and soil carbon sequestration practices to industrial processes that filter carbon out of the air and store it underground. 

The ocean is the largest carbon sink on the planet, already holding about 50 times more carbon in the deep ocean than what is in the atmosphere. There are a number of ways the ocean naturally cycles carbon that could be enhanced and accelerated. And the sheer size of the ocean also means that these potential solutions could be scaled to meaningful levels. 

However, ocean-based carbon dioxide removal options are not well understood; this is why earlier this month more than 200 internationally renowned scientists published an open letter endorsing the need to prioritize and accelerate ocean-based carbon removal research as a potential tool in the climate action toolbox. Since its publication and subsequent media coverage, more than 150 additional scientists have become signatories. 

The letter and growing number of signatories show the support of the scientific community to advance vital research efforts to answer critical questions about the efficacy and the social and environmental effects of these techniques. This research must happen carefully and responsibly, to ensure every action is taken to improve ocean health and avoid and decrease potential adverse impacts. 

Ocean-based carbon dioxide removal approaches have enormous potential. However, society does not yet have nearly enough information to make informed decisions about their use at scale. This is why we call for accelerating responsible research, development and testing to determine which, if any, may ultimately be safe, equitable and feasible. This information is foundational to formulating good public policy on carbon removal. 

There is no other way to say it: We face dire times that will continue to worsen until we reverse the causes. Those of us who are alive today may decide the future of humankind. Our planet is in peril and we need to investigate and employ every possible option. Ocean-based carbon dioxide removal is a potential tool in this fight. Let’s use the power of science to illuminate the path forward. 

Sir David King is the founder of Cambridge’s Centre for Climate Repair. Sware Semesi is the director general of the Marine Parks and Reserves Unit of Tanzania.