Proposed improvements on predicting species' distributions with climate change using bioclimatic envelope modelling

Potential shifts in species' distribution with climate change of three agricultural pests were modelled; each was used as an example to examine a potential limitation of the method and evaluate proposed improvements. The swede midge and pea leafminer bioclimatic envelope models (BEMs) illustrated that results depend on the general circulation model (GCM) and greenhouse gas emissions scenario combination used. The BEM of the pea leafminer's distribution showed that results are spatially variable when GCM projections are used versus a constant rate of increase in temperature and precipitation. Finally, the Colorado potato beetle BEM showed that results depend on which part of the climate data distribution is used for temperature and whether or not the variance around the mean temperature is increased, as is predicted to occur (i.e. more extreme weather). It is suggested that modellers should use multiple GCMs and scenarios as well as incorporate climatic variance and increased variance into models of species' distributions.