Climate change scenarios in fisheries and aquatic conservation research

Scenarios are central to fisheries and aquatic conservation research on climate change. Scenarios project future greenhouse-gas emissions, which climate models translate into warming projections. Recent climate research and global development trends have significantly changed our understanding of plausible emissions pathways to 2100 and climate sensitivities to emissions. Here, we review these developments and make recommendations for scenario use in fisheries and aquatic conservation research. Although emissions pathways are uncertain, recent research suggests that scenarios producing approximately 3.4-4.5W/m2 radiative forcing by 2100 (e.g., scenarios SSP2-3.4 and SSP2-4.5/RCP4.5) might be most plausible. This corresponds to approximately 2-3 degrees C global warming by 2100 with median climate sensitivities, or 1.5-4 degrees C considering climate-system uncertainties. Higher- and lower-emissions scenarios (e.g., RCP2.6 and RCP6.0) might be plausible and should be explored in research. However, high-emission scenarios (RCP8.5/SSP5-8.5, SSP3-7.0) seem implausible and should be used with clear rationales and caveats to ensure results are not misinterpreted by scholars, policymakers, and media. We analyze fisheries and aquatic conservation papers published from 2015 to 2022 in major journals, and find that RCP8.5/SSP5-8.5 are the most commonly used scenarios, though RCP4.5/SSP2-4.5 use has increased since 2020. Studies predominantly project quantitative, rather than qualitative, differences between these scenarios’ impacts.