Global risk assessment of sharks to climate change.

In what has been referred to as a 'perfect storm', it is now clear that we will be concurrently facing both a biodiversity and climate crisis over the incoming decades. In this context, we propose a broadly applicable framework to evaluate the climate-associated risk for marine life at the species-level, based on the ecosystem-level assessment developed by the Intergovernmental Panel on Climate Change (IPCC). We apply this framework to extant marine shark species - given their major ecological and socioeconomic importance, alongside their precarious conservation status -at the global scale. Through the integration of expert-assessed information on each risk dimension, we consider the ecosystem dependencies of the targeted species, alongside with their vulnerability to human pressures. More specifically, we estimate the threat (exposure * hazard) level imposed by different climate change scenarios [Shared Socioeconomic Pathway (SSP) 1, SSP2, SSP3 and SSP5] across meaningful timeframes (2021-2040, 2041-2060 and 2081-2100) and contrast the normalized threat, vulnerability, and risk scores of each species across regions and attributes (order, habitat use, climate preference, lifestyle, trophic position, reproductive mode, and extinction risk category). Our analysis showcases how all shark species should be affected by climate change regardless of the emission scenario. With effects widely expected over the short-term, discrepancies between emission scenarios escalate considerably over time, with associated changes in the level and type of ecological implications. Moreover, with distinct lineages and functional attributes likely to be differently affected and with distinct consequences expected across scenarios, this analysis highlights how climate change may exacerbate the risk of functional and phylogenetic loss documented for this key group of marine predators.