Overview
- Germany’s Potsdam Institute 2025 assessment confirms ocean acidification has moved from “at the limit” to “transgressed,” bringing the total to seven of nine boundaries exceeded.
- Surface ocean pH has fallen by about 0.1 since preindustrial times, a 30–40% rise in acidity, and aragonite saturation has dropped below the 80% preindustrial threshold used for the boundary.
- Researchers identify the main driver as ocean uptake of CO2 from fossil‑fuel emissions, threatening calcifying organisms such as corals, mollusks and key plankton species.
- The other transgressed boundaries are climate change, land‑use change, biosphere integrity, biogeochemical flows of nitrogen and phosphorus, freshwater use, and novel entities/chemical pollution including plastics.
- Experts urge integrated action, including rapid emissions cuts, forest protection, tighter nutrient management and strengthened ocean conservation.