Trend Ocean heat uptake accelerating

Summary

Since at least the 1970s, Earth has absorbed more energy than it radiates away, and the ocean has stored around 90 percent of the resulting excess heat. Recent studies show ocean warming accelerating, with the rate of heat uptake rising by about 0.15 W/m2 per decade in recent decades and ocean heat content hitting a record high in 2025. The report holds that sustained growth in ocean heat reduces the ocean's ability to buffer climate change and makes long-term warming and non-linear Earth-system change more likely. Warming is also a major stressor for marine ecosystems and interacts with other human pressures such as acidification and deoxygenation. The current climate boundary relies only on carbon dioxide concentration and radiative forcing, which do not directly capture how heat accumulates and is distributed. The report is therefore evaluating upper-ocean heat content over the top 2,000 m as a candidate control variable.