A national-scale assessment of climate change impacts on species: Assessing the balance of risks and opportunities for multiple taxa

It is important for conservationists to be able to assess the risks that climate changeposes to species, in order to inform decision making. Using standardised and repeatable methods, we present a national-scale assessment of the risks of range loss and opportunities for range expansion that climate changecould pose for over 3000 plants and animals. Species were selected by their occurrence in England, the primary focus of the study, but climate changeimpacts were assessed across Great Britain, widening their geographical relevance. A basic risk assessment that compared projected future changes in potential range with recently observed changes classified 21% of species as being at high risk and 6% at medium risk of range loss under a B1 climate change scenario. A greater number of species were classified as having a medium (16%) or high (38%) opportunity to potentially expand their distribution. A more comprehensive assessment, incorporating additional ecological information, including potentially confounding and exacerbating factors (e.g. dispersal, habitat availability and other constraints), was applied to 402 species, of which 35% were at risk of range loss and 42% may expand their range extent. This study covers a temperate region with a significant proportion of species at their poleward range limit; the balance of risks and opportunities from climate changemay be different elsewhere. The outcome of both risk assessments varied between taxonomic groups, with bryophytesand vascular plants containing the greatest proportion of species at risk from climate change. Upland habitats contained more species at risk than other habitats. Whilst the overall pattern was clear, confidence was generally low for individual assessments, with the exception of well-studied taxa such as birds. In response to climate change, nature conservationneeds to plan for changing species distributions and an uncertain future.