CERES scientists conducted standardised ensemble projections including six global fisheries and marine ecosystem models, forced with two Earth-system models and four emission scenarios in a fished and unfished ocean, to derive average trends and associated uncertainties.

Without fishing, mean global animal biomass decreased by 5% (±4%) under low and 17% (±11%) under high emissions by 2100, primarily driven by increasing temperature and decreasing primary production. These climate-change effects were slightly weaker for larger animals and in a fished ocean.

Considerable regional variation ranged from strong biomass increases in high latitudes to strong decreases in mid-low latitudes, with good model agreement on the direction of change but variable magnitude. Uncertainties due to differences among ecosystem or Earth-system models were similar, suggesting equal need for model improvement. The ensemble projections provide the most comprehensive outlook on potential climate-driven ecological changes in the ocean to date. Realised future trends will largely depend on how fisheries and management adapt to these changes in a changing climate.

Lotze, Heike K., et al. “Ensemble projections of global ocean animal biomass with climate change.” bioRxiv (2018): 467175. https://doi.org/10.1101/467175