34
Using this information, climate change projections were developed for the five Study Area meteorological
stations described in Section 4.2. Projections were developed for several climate change scenarios
(Section 4.7.2). The new climate sequences that were derived were then analysed to identify key
attributes of the projected climate change regime. Refer to
Appendix B
for detailed scenario data.
4.7.2. Scenarios
The climate change analysis documented in this report and included in the accompanying data library
considered five main scenarios. The scenarios account for several timeframes and global greenhouse
gas emissions scenarios, as follows:
x
2030 high emissions
- the scenario represents the period between 2020 and 2039. A high
emissions scenario (A1FI) was selected, as this is similar to the current trajectory for global
greenhouse gas emissions. DENR (2010) found that there are few substantive seasonal or
annual differences in climate change projections between emissions scenarios at this time. Much
of the change in climate at this time is “locked in”, in that it will be caused by greenhouse gases
that are already in the atmosphere or will be produced with current energy and industrial
infrastructure and land use patterns.
x
2050 low and high emissions
– the scenario represents the period between 2040 and 2059.
High and low emissions scenarios (A1FI and B1, respectively) were included because by this
time it is possible for technology, international climate change negotiations and other influences
to have significantly influenced the global greenhouse gas emissions trajectory.
x
2070 high and low emissions
– the scenario represents the average of projections for 2060-
2079. The high emissions scenario reflects a global context in which there is little effective action
to limit greenhouse gas emissions and is the most extreme scenarios considered. The low
emissions scenario reflects a lower greenhouse gas emissions trajectory, which results from
effective global action to mitigate emissions.
In most cases in this report, climate change projections for only the 2030 and 2070 scenarios have been
presented. These show the range that is possible over this period. 2050 values are intermediate between
the 2030 high emissions scenario and the respective emissions scenarios for 2070. While the high
emissions scenario appears more likely for 2030, there is no more or less likely emissions scenario for
2050 or 2070.
In some cases in this report, statistically “extreme” values of projections for one or more emissions
scenarios are used to highlight the potential risks or implications of climate change. For rainfall, this may
involve using the 10
th
and 90
th
percentile rainfall projections (i.e. the 10
th
[dry] and 90
th
[wet] percentile
results from the ensemble of up to 23 GCMs used to produce the data presented in the
data set). For temperature, this only involves using the 90
th
percentile (high extreme) increase in temperature. An analysis of outputs of the individual GCMs that
have reasonable predictive skill for South Australia (DENR, 2010) shows that most models project that
the climate will become both warmer and drier.
