35
Use of these values is not intended to suggest that such outcomes are likely results of climate change.
Revised projections, currently under development by a project which is funded through the Goyder
Institute, will provide higher resolution model outputs over the next 1-2 years or so. Analyses provided
here are not intended to be definitive in nature and new, updated models should be considered in light of
future analyses.
A data library has been developed that incorporates all climate scenarios outputs, which is an
accompaniment to this report.
4.7.3. Uncertainty
Climate change projections are useful tools to guide decision-making about climate risks. They indicate
the expected trend in climate variables under various emissions scenarios and the likely quantum of
change. While probabilities may be provided for GCM projections for given emissions scenarios (as in
Figure 4.12
), no probabilities may be attached to the scenarios themselves.
Climate change projections reported here for the five Western Adelaide region meteorological stations are
not the result of “downscaling”. Climate change projections (as amounts or percentage changes) from the
Climate Change in Australia web site (
) are merely used to perturb
or adjust historical climate change records for the 1980-1999 reference period.
Various other methods (e.g. use of regional-scale climate models or statistical downscaling techniques)
may be used to produce climate change projections with much finer resolution than those derived solely
from GCMs. While this may be useful, such projections are subject to the uncertainties inherent in GCMs,
as well as in their own methodologies. While the increased spatial resolution achieved may convey
greater accuracy, this is not necessarily the case.
The reliability of climate change projections varies between climate variables. In general, global
projections are more certain than regional projections and temperature projections are more certain than
those for rainfall. Changes in average conditions are also more certain that changes in extremes. While
climate model projections have improved in recent years, some important climatic influences, including
ENSO, are currently not well represented.
The hydrological cycle is expected to strengthen as the planet warms. Recent observations suggest that
this is currently occurring at double the rate projected by climate models. This suggests that changes in
mean and extreme rainfall may occur much more rapidly that climate modelling currently suggests.
4.7.4. Changes in Temperature
4.7.4.1. Temperature projections
Annual temperatures are projected to increase throughout South Australia through the 21
st
century in
each of the climate change scenarios considered (
Figure 4.13
). The median projection for the Study Area
is for temperature to increase by 0.6-1.0°C by 2030 and by 1-2.5°C by 2070. Under the most extreme
scenario for 2070 (90
th
percentile GCMs), average temperature is projected to increase by 3-4°C by 2070.
The cooler of the GCMs project that average temperatures will increase by 1.5-2.0°C by 2070.
