Towards a Less Habitable Ocean

Ocean warming and associated deoxygenation caused by anthropogenic global warming are impacting marine ecosystems. This article contextualizes and provides perspectives on key insights from a recently published study by Fröb et al. in Earth's Future (2024). The authors employ historical and high-emission scenario simulations through a state-of-the-art Earth system model to detect abrupt and persistent changes in the viability of marine habitats by leveraging an ecophysiological framework that quantifies how temperature and oxygen jointly limit the distribution of life in the ocean for a number of ecophysiotypes. A changepoint analysis is used to objectively detect shifts in decadal to multi-decadal mean states in potential marine habitats. They observe a decrease in the ocean volume capable of providing viable habitats for those ecophysiotypes with positive sensitivity to hypoxia. About half of these decreases occur abruptly, thus highlighting potential risks on the capacity of marine organisms to cope with a changing environment.