Advancing food-web modelling capabilities to analyse global ocean futures

Abstract

There has been considerable effort to predict the impact of climate change and anthropogenic activities on the biophysical environment, biodiversity, and marine resources at regional and global scales. To further our understanding of how changes in the environment and marine resources will affect marine ecosystems, there is a need for advancing global integrated assessments. We improved a previously developed spatial-temporal ecosystem model of the global ocean (EcoOcean) (Christensen et al., 2015), spanning food web dynamics from primary producers to top predators, and including worldwide fisheries. We enhanced its ability to reproduce spatial-temporal ecosystem dynamics by linking spatial-temporal species dynamics and distributions to main environmental conditions that change under climate impact (e.g. primary production, sea surface temperature), accounting for varying species compositions of species groupings over time and space (Coll et al., submitted). The updated modelling platform was used to simulate past and future scenarios of climate change and fisheries, considering structural uncertainty and alternative input drivers using standardized outputs from Earth-System Models (ESMs) and contrasting emission scenarios using the Representative Concentration Pathways (RCPs) for historical (1950-2005) and future (2006-2100) periods. Ecological aggregated indicators and biomass from species groupings were used to compare ecological predictions among scenarios following a standardized protocol (Tittensor et al., 2019; Lotze et al., 2019). Comparing results from scenarios with and without fishing allowed us to evaluate how climate-driven responses differed between fished and hypothetically non-fished oceans. The study sets a baseline to further develop global ocean analyses and contribute to the quantification of cumulative effects assessment of multiple stressors and plausible ocean-based solutions to global change, considering species, biodiversity and food-web spatial-temporal dynamics