New report reveals major risks in turning oceans into carbon sinks

Scientists are exploring ways to use the ocean to remove carbon dioxide, but current approaches are not ready for large-scale use. Until rigorous monitoring and environmental protections are established, emissions reductions remain the most reliable path forward.

The world's oceans are expected to play a key part in drawing carbon dioxide out of the atmosphere to help slow dangerous climate warming. A central question is whether the technologies designed for this role are ready to be expanded.

According to an expert panel reporting to the European Union, the answer is no.

At least, not yet -- not until there are strong safeguards proving that these methods, known as marine carbon dioxide removal technologies, function as intended and do not create new environmental problems.

Divers among reefs

Marine carbon dioxide removal approaches rely on the ocean's natural capacity to absorb carbon. Some strategies use biological processes, such as increasing plankton or seaweed growth so they can take up carbon dioxide as they develop. Others rely on chemical or physical techniques, including systems that directly remove carbon dioxide from seawater.

Once carbon is extracted from the upper layers of the ocean, it can be stored in deep-sea sediments, on the ocean floor, in the deep ocean, in geological formations, or in products designed to last for long periods.

Protecting the Ocean While Exploring New Climate Tools

"This is about safeguarding the oceans for a common good. The oceans can be part of the climate solution, but we need to strengthen the way we safeguard them before we scale things up," said Helene Muri, a senior researcher at NILU, the Norwegian Institute for Air Research and the Norwegian University of Science and Technology (NTNU).

Muri led an expert group formed by the European Marine Board to evaluate the issue.v

The group's findings appear in a new report, "Monitoring, Reporting and Verification for Marine Carbon Dioxide Removal," released during COP30, the UN climate conference now taking place in Brazil.

Rising Temperatures and the 1.5°C Threshold

Earth's temperature is rising more quickly than countries expected when they agreed in Paris to keep global warming within 1.5°C above "pre-industrial levels."

During his opening remarks at the COP30 Leaders' Summit on November 6, UN General Secretary António Guterres called attention to the seriousness of the climate outlook.

"Science now tells us that a temporary overshoot beyond the 1.5°C limit -- starting at the latest in the early 2030s -- is inevitable," he said. "Let us be clear: the 1.5°C limit is a red line for humanity. It must be kept within reach. And scientists also tell us that this is still possible."