Climatic change and the British butterfly fauna: Opportunities and constraints

The magnitude of climatic warming, projected from increasing concentrations of infrared absorbing atmospheric gases, will have a number of direct and indirect effects on British butterflies. It is predicted that many influences will be adverse, especially those mediated through larval hostplants, but that species will be affected differently, some may benefit, and that there will be regional contrasts in impact. A scheme is discussed for assessing the vulnerability of species on their hostplant and habitat associations. Also considered is the potential for species to adapt to changing conditions. Climatic warming may reduce the regional contrasts in species diversity and population status between northern and southern Britain, as range expansions and upland colonization are predicted for the north and reduced populations and population extinctions for the south. However, climatic warming offers potential for new residents and migrants in southern Britain.