Ocean Acidification Breaches Planetary Boundary as Scientists Detail Triple Ocean Crisis

Overview

• PIK’s Planetary Health Balance 2025 reports that the planetary boundary for ocean acidification has been crossed, with seven of nine Earth-system limits now beyond the safe zone.
• Copernicus’ Ninth State of the Ocean details accelerated warming since the 1960s, a record global sea-surface temperature in spring 2024, persistent marine heatwaves, and repeated Arctic and Antarctic sea-ice minima between December 2024 and March 2025.
• Oceans have absorbed roughly 20% to 30% of anthropogenic CO2 since the 1980s, driving pH declines that damage corals and calcifying organisms and threaten fisheries and the livelihoods of about 300 million people.
• Scientists warn the ocean’s carbon sink could weaken substantially, with a potential loss of up to roughly 30% in CO2 absorption capacity.
• Pollution now pervades all basins, with large annual plastic inflows and contaminants detected from plankton to whales, while the Mediterranean is flagged for severe impacts to aquaculture species such as mussels and oysters and to local tourism.