Perspectives on most plausible climate futures, and recommendations for using scenarios in fisheries and aquatic conservation research

Climate change projections are central to fisheries and aquatic conservation research, and to planning for a warming world. Such projections include assumptions about future emissions pathways and climate-system sensitivity to emissions. Fisheries and aquatic conservation research typically uses emissions scenarios created for the Intergovernmental Panel on Climate Change (IPCC). However, recent climate research and global development trends have significantly changed our understanding of the ranges of plausible emissions pathways to 2100 and climate sensitivities. Here, we provide a concise review of these updates to our understanding of climate futures, and we make recommendations for best-practice use of climate change scenarios in fisheries and aquatic conservation research. Although emissions pathways are subject to deep uncertainty, recent research suggests that emissions scenarios producing a range of approximately 3.4-4.5W/m2 radiative forcing by 2100 might be most plausible. With median climate sensitivities, this corresponds to approximately 2-3 degrees C global warming by 2100. Climate-sensitivity uncertainties expand this range to approximately 1.5-4 degrees C. In terms of the Shared Socioeconomic Pathways (SSPs) and Representative Concentration Pathways (RCPs), radiative forcing outcomes mostly fall between SSP2-3.4 and SSP2-4.5/RCP4.5, though higher and lower emissions scenarios (e.g., RCP2.6 and RCP6.0) might be plausible and should be explored in research. However, we argue that uses of the highest-emission scenarios (RCP8.5/SSP5-8.5, SSP3-7.0)—which currently predominate the literature—should come with clearly articulated rationales and appropriate caveats to ensure results are not misinterpreted by scholars, policymakers, and media.