Temperature trends
Australia has warmed in response to a warming global system by around 1°C in both surface air temperature and sea surface temperature since 1910, with most of the warming since 1950 (Figure 13). Warming has been more notable across autumn, winter and spring, with the smallest increases in summer. Both night-time minimum temperatures and daytime maximum temperatures have increased, with more warming at night.
Figure 13: Trends in Australia’s mean temperature. Sources: CSIRO & BOM
Australia spans over 30° of latitude and is affected by many different weather systems producing large natural variations. While extreme weather has always been part of Australia’s complex climate, some changes stand out from the background variability. There have been significant increases in the frequency of high-temperature extremes and increases in the duration, frequency and intensity of heatwaves over large parts of Australia (Figure 13). Extremely cold days occur less often.
While heatwaves have occurred in the past, the frequency of intense, large-scale heatwaves has increased across spring, summer and autumn and especially over the last 20 years. The warmest spring seasons on record have been found for 2013, 2014 and 2015. Summer 2016–17 saw prolonged and extreme heat over SA. Winter warm spells are lasting longer, occurring more often and becoming more intense. Australia had its warmest winter on record, for average maximum temperatures, in 2017, reaching nearly 2°C above average. In 2017, it was also Australia’s third warmest year since national records began in 1910. Seven of Australia’s 10 warmest years on record have occurred since 2005.
Australia’s temperatures are projected to continue increasing with more extremely hot days and fewer extremely cold days.
Average annual temperatures across SA have been increasing since the 1970s, with the highest rates of increase in the north of the state. The average annual temperature across SA is now about 0.6°C warmer than in the 1970s. The coolest parts of the state have seen the lowest increases, while the highest rate of increase is in the arid lands (1.5°C in mean annual temperatures over the past 47 years), which is already the warmest part of SA.
South Australia’s maximum temperature is expected to increase in all regions and seasons with a greater increase inland and further north. Minimum temperatures are projected to increase less than maximum temperatures, with the largest increase in autumn. By the end of the century, maximum temperatures are expected to increase by 1.5 to 4°C, depending on the region (Figure 14) and emissions scenario (Table 7). More days above 40°C are also projected.
Figure 14: Natural resources management (NRM) regions of SA
Table 7: Temperature projections for South Australia to 2090
|
|
Intermediate emissions scenario |
High emissions scenario |
||
|---|---|---|---|---|
|
NRM region |
Maximum temperature |
Minimum temperature |
Maximum temperature |
Minimum temperature |
|
Adelaide and Mount Lofty Ranges |
1.8°C |
1.4°C |
3.4°C |
2.9°C |
|
Eyre Peninsula |
1.8°C |
1.4°C |
3.3°C |
2.8°C |
|
Kangaroo Island |
1.5°C |
1.2°C |
2.8°C |
2.4°C |
|
Northern and Yorke |
2.2°C |
1.6°C |
3.7°C |
3.2°C |
|
SA Arid Lands and Alinytjara Wilurara |
2.1°C |
1.9°C |
4°C |
3.7°C |
|
SA Murray-Darling Basin |
1.9°C |
1.5°C |
3.6°C |
3.1°C |
|
South East |
1.6°C |
1.4°C |
3.2°C |
2.7°C |
Source: Goyder Institute
The Climate Council describes the following projected impacts for South Australia.
Extreme heat:In Adelaide, the number of hot days per year is projected to increase from 20 to 26 per year by 2030 (relative to 1981–2010), increasing to 47 per year by 2090 under a high emissions scenario (CSIRO and BOM 2015). Earlier projections using data from BOM (2013) and CSIRO and BOM (2007) showed that for the 2000–09 period, the number of hot days in Adelaide has already exceeded the earlier 2030 projections.
Extreme rainfall: Maximum 1-day rainfall is expected to increased by up to 17% for the southern areas of South Australia by the end of the century for the high emissions scenario, relative to 1986–2005 (CSIRO and BOM 2015)
Bushfires: The Forest Fire Danger Index may increase across southern Australia, including coastal part of South Australia, by 7% and 30% in 2030 and 2090, respectively, under a high emissions scenario (CSIRO and BOM 2015).
Sea level rise: Adelaide is expected to experience a mean seal level rise of up to 0.25 m by 2050 releative to 1986–2005 under a high emissions scenario (McInnes et al 2015). Adelaide suburbs that are most at risk of being partially submerged by 2050 include Tennyson, West Lakes and Port Adelaide (Coastal Adapt 2016).
Source: Climate Council
Bureau of Meteorology (BOM) special climate statement on 13 April 2018:
..the highest April temperatures on record occurred for the states of South Australia, Victoria and New South Wales.… The temperature of 42.2°C at Nullarbor on the 9th was a new state record for South Australia.