Ocean acidification from CO2 absorption is altering marine chemistry in ways that impair the sensory systems, physiology, and behaviour of marine animals.
Ocean acidification is a slow-moving welfare emergency whose impacts on individual marine animals are real but diffuse. Fish that cannot smell predators and therefore fail to avoid them die earlier, more frequently, and more violently. Shellfish larvae that cannot build shells die during their most vulnerable life stage. Coral reef animals that lose their habitat face starvation and exposure in degraded reef structures. These are welfare harms distributed across billions of individuals across all the world oceans. Like climate change generally, the welfare response requires systemic carbon emission reduction — individual consumer choices matter only to the extent that they contribute to the systemic transition needed.