A few years ago we published a paper (Mantyka-Pringle et al. 2012) in which we used a meta-analysis to quantify empirically the effect of interactions between climate change and habitat loss on species declines due to habitat loss. In general we showed that the effect of habitat loss was greatest in areas with the highest maximum temperatures but lowest in areas where average rainfall had increased over time. This was the first attempt to empirically estimate these interactions.
But we were also interested in how these interactions effects might translate into effects on global biodiversity once the distribution of species and potential future changes in land cover and climate were taken into account. And we also wanted to know whether the interactions modified the ranking of conservation priorities. We reasoned that once we accounted for the interactions, if substantial changes in the ranking of conservation priorities occured then we should be taking these interactions seriously in conservation prioritisation. In a new paper of ours just out in Biological Conservation we explored this issue (Mantyka-Pringle et al. 2015).
We used a risk assessment framework to assess the risk of future land cover change for birds and mammals at a global extent and quantified this risk when accounting for the interaction between climate change and habitat loss (i.e., the amount by which climate affects the impact of habitat loss) and when the interaction is ignored. We found that the interaction between climate change with habitat loss may increase the aggregate impact of land cover change on birds and mammals by up to 43% and 24% respectively. But, interestingly, the effect was highly spatially variable. In our study, negative effects of the interaction were most prominant in Sub-Sahara Africa and Central America. But some areas were predicted to actually benefit from the interaction, including areas of North America, South America, Central and West Africa, Eastern Europe, South and Central Asia, and Southeast Asia. This spatial variability is driven by spatial variation in predicted temperatures and rainfall changes, but also by variation in the rate of loss of habitat and the distribution of species.
We then ranked Conservation International’s Bioodiversity Hotspots based on the risk of species decline due to habitat loss with and without the climate change / habitat loss interaction. This showed that 15–32% of terrestrial biodiversity hotspots change by two or more ranks for both birds and mammals once the interaction was accounted for. Consequently, ignoring the interaction could have important implications for the performance of prioritisation approaches for global biodiveristy.
As with all models there are uncertainties inherent in our model predictions. However, our work emphasises the need to think carefully about how drivers of biodiversity change interact for biodiversity conservation. It is likely that these effects are more important than we currently assume.