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the continent, the required movement distance is 0 km. For temperature, however, the
10 th percentile equates to less than approximately 150 km.
Figure 14: The 10 th percentiles of the minimum distance (km) an organism would
have to travel by 2085 to stay within 2 SDs of the current annual mean
temperature, and 1 SD of the current precipitation mean.
3.4.6 Summary of climatic stability analyses
From the preceding, it is clear that shifts in temperature are going to be a major impact
on Australia’s biodiversity. Shifts in precipitation are inherently uncertain, but despite
this the range of the projected shift is relatively modest against the backdrop of natural
inter-annual variation in precipitation across the Australian continent.
Shifts in temperature are far more certain and are, even against the backdrop of normal
inter-annual variation, going to be very large. Indeed the shifts in temperature will
often be larger in magnitude than (though opposite in direction to) climate shifts
associated with the last ice age. Given the magnitude of shifts in temperature, the
only response available to most taxa will be to move. Movement will likely be a
feasible option for lowland populations close to areas of major topographic
relief. Populations distant from mountainous areas, or which are located on top
of these mountainous areas will have to move very large distances to find
equivalent temperatures to those they currently experience. Low vagility taxa in
this situation may well risk extinction without management intervention. The habitat of
mountaintop species becomes a refugium for lowland species; and the nearest
refugium for mountaintop species may well be impossibly distant.
3.4.7 Species distribution modelling
At this point we move from an analysis of raw climate variables to projections of
species distributions and how these might shift as a consequence of climate change.
The underlying assumption behind this approach is that the climatic envelope currently
utilised by a species is indicative of the climatic envelope that species will occupy in the
future or did occupy in the past.
Using the Maxent software, we fitted species distribution models for taxa across four
major taxonomic groups (birds, mammals, reptiles and amphibians). We then used the
species–climate relationships imputed from this modelling process to predict the
location of suitable climates for each of these species in the future.
28 Climate change refugia for terrestrial biodiversity