Although it is widely accepted that future climatic change ¿ if unabated¿is likely to have major impacts on biodiversity, few studies have attempted to quantify the number of species whose populations have already been impacted by climate change. Using a systematic review of published literature, I will identify mammals for which there is evidence that they have already been impacted by climate change. I will model the relationships between observed responses and intrinsic (for example, body mass) and spatial traits (for example, temperature seasonality within the geographic range). Using this model, I will estimate the proportion of terrestrial non-volant mammals that may have already been negatively impacted by climate change in at least part of their
distribution. These results will be helpful to highlight populations of threatened species that are likely already impacted by climate change, and areas and species that conservation managers, conservation planners and policy makers must take this into account in their efforts to safeguard the future of biodiversity.
Trait-based vulnerability assessements use species biological characteristics as predictors of extinction risk due to climate change, often in combination with estimates of exposure. Methods typically involve selecting traits related to sensitivity (e.g., typically describing ecological specialization, inter-specific interactions) and adaptability (i.e. traits related to dispersal and phenotypic adaptability) and scoring each according to observations or expert judgment. Drawbacks with trait-based vulnerability assessements are that precise vulnerability thresholds associated with each trait are often unknown, necessitating selection of arbitrary, relative thresholds for categories of higher or lower extinction risk. Therefore, traits are often weighted equally even if some characteristics are likely to be more important than others in determining climate change vulnerability. This will be the first study investigating the quantitative relationship and the causality between biological and ecological characteristics of mammals, and their observed responses to climate change. This will allow me to fit predictive models of extinction risk under climate change for the species analysed in this meta-analysis, and make inferences about the risk of extinction about species possessing a different mix of intrinsic traits. Additionally, this study will provide a data-driven validation of the expert-based criteria so far used to assess extinction risk from climate change of species based on their intrinsic characteristics.