Could the oceans—where life once evolved—help save the planet and humanity from climate catastrophe? A new report suggests they might. Released on Dec. 8 by the U.S. National Academies of Sciences, Engineering and Medicine, or NASEM, the study explores tantalizing possibilities for drawing carbon out of the atmosphere and sequestering it in the oceans through a mix of nature-based solutions and technological innovations. Getting these climate interventions to scale will of course be a significant challenge. But another challenge may be just as difficult to solve: reconciling these solutions with international law and state obligations.
Notwithstanding incremental progress at last month’s United Nations climate summit in Glasgow, the world is poised to warm to 2.7 degrees Celsius above preindustrial levels by the end of the 21st century, with destabilizing environmental, economic and societal implications. Humanity will need a broad portfolio of strategies to manage and reduce climate risk, based on at least four pillars: aggressive emissions reductions, adaptation to build resilience, carbon dioxide removal and—although it remains controversial—possibly solar climate intervention. Unfortunately, the pace of emissions reduction is lagging, while adaptation strategies are essentially palliative. Agreement on solar climate intervention, meanwhile, remains elusive. That leaves carbon dioxide removal, or CDR, which encompasses a broad array of techniques that capture and store carbon.
To date, most carbon removal efforts—whether they involve planting trees or inventing machines to pull carbon dioxide directly from the air and store it—have been land-based. That is poised to change, as scientists turn to the oceans. Covering more than 70 percent of the Earth’s surface, oceans have already insulated humanity from the worst effects of accumulating greenhouse gas emissions by serving as a massive carbon and heat sink. They absorb about a quarter of anthropogenic carbon dioxide and 90 percent of the heat from global warming. But this role has come at great cost: Oceans are now 30 percent more acidic than they were at the start of the Industrial Revolution, and the hottest they’ve been in human history, threatening the survival of marine species and ecosystems.