Ocean conditions are projected to continue diverging from a pre-industrial state , with the magnitude of warming, acidification, deoxygenation, sea level rise and other climate-induced drivers depending on the emission scenario , and to increase risk of regional extirpations and global extinctions of marine species . Marine species richness near the equator and in the Arctic is projected to continue declining, even with less than 2℃ warming by the end of the century . In the deep ocean, all global warming levels will cause faster movements of temperature niches by 2100 than those that have driven extensive reorganisation of marine biodiversity at the ocean surface over the past 50 years . At warming levels beyond 2°℃ by 2100, risks of extirpation, extinction and ecosystem collapse escalate rapidly . Paleorecords indicate that at extreme global warming levels , mass extinction of marine species may occur . 
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report