Ocean acidification from CO2 absorption is impairing calcification, sensory systems and behaviour in marine species, with significant but often overlooked welfare implications.
Ocean acidification welfare impacts operate across scales from individual physiology to ecosystem function. Individual fish with impaired sensory systems make worse decisions about predator avoidance and habitat selection, increasing mortality risk. Calcifying animals struggle to build shells and skeletons, creating physical vulnerability and metabolic cost. Coral reef collapse eliminates habitat for millions of species, causing population-level welfare catastrophe through starvation, predation exposure and reproductive failure. These are slow-moving welfare disasters that are difficult to perceive because they unfold over decades. Climate action that reduces CO2 emissions is simultaneously the largest-scale animal welfare intervention available.