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Figure 1: (Left) The areas of Australia that have the greatest stability in
temperature (the 10 th percentile of the minimum distance an organism would
have to travel by 2085 to stay within 2 SDs of current norms are shown in blue);
(Right) the areas with the greatest biotic refugia potential between now and 2085.
The biotic refugia potential index (as shown in Figure 24) is the aggregation of the
highest percentile for modelled incoming and lowest percentile for modelled outgoing
species in each of the four taxonomic groups summed together. The darker colours
indicate the highest score, which corresponds to the greatest overlap of indices. The
two approaches give broadly concordant results. Increasing values on the scale bars
indicate increasing climate stability and increasing biotic stability respectively.
3.4.1 Environmental stability
Here we investigated change in climate in the past as well as that of a projected future.
We measured shift in climatic variables on both an absolute scale (for annual mean
temperature), a proportional scale (proportional difference from current precipitation),
and a relative scale (for both temperature and precipitation). The relative measure was
the SD of current inter-annual variation in our climate metrics.
When examining future climate projections, there is inevitable uncertainty, much of
which is captured by variation across the various GCMs used to develop climate
projections. Therefore, for all our inference about the future, we report results across
the 18 GCMs under the RCP that we are most closely tracking (RCP 8.5, which is the
IPCC’s worst- case scenario).
The future climate projections show that here are very few parts of the Australian
continent that will see temperature shifts less than two SDs above current conditions.
The full range of outcomes across different RCPs and GCMs can be found in
APPENDIX 2. Climate stability. These are shifts of similar magnitude (but opposite in
direction) to those seen during the last ice age (changes which occurred over
thousands of years, instead of the 72 years of our forecast period).
As well as assessing the projected climate change, we also assessed paleological
climate change. The reason paleological climate change is important is because
regions with little climate change in the past tend to be rich in endemic species and
species that are less resilient to future climate change. By identifying areas with high
paleological climate stability, we expect to identify areas where the largest number of
endemic, low- resilience species are likely to live. If these areas are not the same as
our refugia under climate change, then we are at increased risk of biodiversity loss.
Climate change refugia for terrestrial biodiversity 17