Oceans, forests, and other natural systems absorb roughly 40% of the carbon dioxide humans produce each year, but the policies and financial frameworks designed to protect them aren't keeping up with the growing stress they face. That's the central conclusion of Nature capital: the unpriced carbon, a report Wood Mackenzie published in August 2026. The study warns that these natural carbon sinks—which serve as the unpriced foundation of global climate targets—are weakening under mounting pressure, even as most climate models fail to account for their deteriorating health.
In 2025, human activities across energy, agriculture, waste, and land use produced gross carbon dioxide emissions of 48 GtCO2 annually. Natural sinks pulled approximately 18 GtCO2 back out of the atmosphere during the same period, cutting net emissions to around 30 GtCO2, according to the report. Oceans alone accounted for roughly 12 GtCO2 of annual uptake, while forests contributed another 6 GtCO2. Net CO2 emissions from human activities have climbed more than 80% since 1990. Meanwhile, engineered carbon removal technologies—including direct air capture and bioenergy with carbon capture and storage—removed just 0.08 GtCO2 in 2025, about 200,000 times less than the CO2 oceans absorbed over the same stretch.
The vast majority of CO2 removal has historically relied on natural systems, but those systems are shrinking. Global forest area has contracted by 1.5 million square kilometers since 1990, with deforestation adding 5 to 6 GtCO2 of emissions each year. The land-use sector reached near-neutral net emissions in 2024, losing its historical role as a carbon sink. Five major Earth system tipping points—permafrost thaw, Amazon dieback, boreal forest fires, coral reef die-off, and Atlantic Ocean circulation disruption—carry a combined potential to release more than 750 GtCO2, and some are already in motion. Canada's 2023 boreal fires alone released 3 GtCO2, flipping the boreal forest from sink to source. The report states that carbon prices in most compliance markets range from $5 to $90 per ton of CO2, levels that don't reflect the true cost of sink degradation.
Even under the most ambitious climate scenario, residual energy-sector emissions don't vanish. The report's net zero scenario, which reaches global net emissions of zero by 2050, leaves approximately 11 GtCO2 of annual energy emissions on the table. Under the country pledges scenario, which hits net zero by 2060, that figure rises to around 14 GtCO2. Current policy frameworks treat natural sinks as free infrastructure while pricing only emissions, creating what the study calls a structural blind spot in climate policy. Rising temperatures create a feedback loop: more warming fuels more fires, which further weakens absorption capacity. Protecting and restoring forests could deliver 3 to 6 GtCO2 of mitigation each year, but financing gaps in the land-use sector mean the natural sink capacity needed to absorb residual emissions remains underdeveloped.
"Unlike the energy transition, which can accelerate in later years, ecosystem collapse is permanent on human timescales. Each decade of inaction removes future optionality," said Roshna Nazar, senior analyst for energy transition scenarios and technologies at Wood Mackenzie. The report warns that the 2026 to 2035 window is decisive, with scenario analysis showing sink trajectories diverge sharply based on action taken now. Without stronger carbon pricing, scaled-up finance for nature, and urgent policy action, the study concludes, absorptive capacity will continue to weaken—and any net zero strategy that assumes stable natural absorption without assessing sink health is building on unverified foundations.