Climate & resilience
Ocean carbon uptake slips by about six percent as warming undermines a key climate buffer
UN agencies report that climate‑driven warming has already cut the ocean’s carbon‑absorption capacity by approximately six per cent, weakening its role in soaking up around 30 per cent of human CO₂ and about 90 per cent of excess heat, and call for expanded ocean monitoring, blue‑carbon ecosystems and support for vulnerable island nations.
Ocean’s shrinking climate service
The United Nations environment agency and climate secretariat released a joint report indicating that the ocean currently absorbs around 30 per cent of anthropogenic carbon dioxide and about 90 per cent of the excess heat trapped by greenhouse gases. However, climate‑driven warming has already lowered that carbon‑absorption capacity by approximately six per cent. Higher sea temperatures and shifting chemistry are weakening the ocean’s role as a carbon sink, a trend the report says could accelerate if current warming continues. The loss of this natural service means more CO₂ stays in the atmosphere, intensifying the climate challenge.
Building ocean carbon intelligence
A major obstacle identified in the assessment is the scarcity of reliable monitoring data, especially across the Southern and Indian Oceans, the Arctic, and many coastal zones. The report urges the development of a comprehensive “ocean carbon intelligence” system that combines scientific sensors, data platforms, modelling tools and local knowledge. Among the three technology pathways examined, ocean monitoring—comprising observation networks, real‑time sensors and advanced modelling—is described as the most mature and immediately needed. Strengthening these systems would close knowledge gaps and enable better management of the ocean’s carbon dynamics.
Island nations and blue‑carbon pathways
The study highlights blue‑carbon ecosystems—mangroves, seagrasses and salt marshes—that together sequester about 407 million tonnes of CO₂ each year, with restoration offering additional storage potential. Small Island Developing States, which emit less than one per cent of global greenhouse gases, are on the front lines of ocean change. The report cites Seychelles’ 2015 debt‑for‑nature swap that created a trust fund for marine conservation and the Pacific islands’ effort that trained more than 100 people in blue‑carbon assessment, providing data for national climate plans. Integrating Indigenous and local expertise is also emphasized as essential for effective coastal stewardship.