Coral bleaching, Great Barrier Reef Marine Park Authority, Australian Government
Once a system’s degradation begins, in general it does not stop unless the thing that caused it to begin is removed. In this case, warming has caused the crossing of the ocean acidification threshold. There are situations where if warming is halted, natural buffering and ocean circulation could restore ocean acidification with time, but generally, a system does not self restore once degradation begins, unless the warming or warming effects that caused the degradation to begin are removed.
Abstract, “Ocean acidification has been identified in the Planetary Boundary Framework as a planetary process approaching a boundary that could lead to unacceptable environmental change. Using revised estimates of pre-industrial aragonite saturation state, state-of-the-art data-model products, including uncertainties and assessing impact on ecological indicators, we improve upon the ocean acidification planetary boundary assessment and demonstrate that by 2020, the average global ocean conditions had already crossed into the uncertainty range of the ocean acidification boundary. This analysis was further extended to the subsurface ocean, revealing that up to 60% of the global subsurface ocean (down to 200m) had crossed that boundary, compared to over 40% of the global surface ocean. These changes result in significant declines in suitable habitats for important calcifying species, including 43% reduction in habitat for tropical and subtropical coral reefs, up to 61% for polar pteropods, and 13% for coastal bivalves. By including these additional considerations, we suggest a revised boundary of 10% reduction from pre-industrial conditions more adequately prevents risk to marine ecosystems and their services; a benchmark which was surpassed by year 2000 across the entire surface ocean.”
Findlay et al., Ocean Acidification – Another Planetary Boundary Crossed, Global Change Biology, June 9, 2025.
https://onlinelibrary.wiley.com/doi/epdf/10.1111/gcb.70238
