Indicator /

Climate trends

Indicator
CC1: Climate trends

Climate change is having a significant impact on the ACT, with clear evidence of a warming climate and increased occurrence of heat days. Rainfall is variable, but most recent years have been drier than average. Projections suggest a worsening climate with hotter temperatures and decreased rainfall.

Condition & trend
  • Trending arrow Poor
  • Trending arrow Fair
  • Trending arrow Good
Data quality
High
Indicator assessment legend
Condition
  • Poor
  • Fair
  • Good

Environmental condition is healthy across the ACT, OR pressure likely to have negligible impact on environmental condition/human health.

  • Poor
  • Fair
  • Good

Environmental condition is neither positive or negative and may be variable across the ACT, OR pressure likely to have limited impact on environmental condition/human health.

  • Poor
  • Fair
  • Good

Environmental condition is under significant stress, OR pressure likely to have significant impact on environmental condition/ human health.

  • Poor
  • Unknown
  • Good

Data is insufficient to make an assessment of status and trends.

Trend
Trending arrow

Improving

Trending arrow

Deteriorating

Stable

?

Unclear

Data quality
High

Adequate high-quality evidence and high level of consensus

Moderate

Limited evidence or limited consensus

Low

Evidence and consensus too low to make an assessment

N/A

Assessments of status, trends and data quality are not appropriate for the indicator

Background

The data presented in this indicator shows the impact of climate change on temperature and rainfall the ACT region. Projected climate trends are also discussed.

The ACT’s climate is determined by atmospheric conditions and sea-surface temperatures. The main drivers of natural climate variability include (but are not limited to) the El Niño–Southern Oscillation (including La Niña cycles), the Indian Ocean Dipole, and the Southern Annular Mode which influence climate across south-eastern Australia. Changes in the frequency and duration of these drivers cause year-to-year variations in temperature and rainfall. 

This natural climate variability is now significantly influenced by human-induced climate change. Evidence of global and regional warming caused by greenhouse gas emissions is incontrovertible.

Condition and trends

Observed surface temperature

The ACT’s annual mean maximum temperatures have risen by over 1.5°C since records began in 1926 (Figure CC1). The frequency and severity of hot temperatures have also increased (see Figure CC2). Since 2013, every year has been among the eleven warmest years on record for daytime temperatures and 2018 was the warmest year on record for daytime temperatures in the ACT. 

Figure CC1: ACT mean maximum temperature anomaly (as calculated from the 1961 to 1990 average), 1926 to 2018.
Data sourced from Bureau of Meteorology, Canberra Airport site.

In the ACT, minimum temperatures have warmed the most, with annual mean minimum temperatures having risen by around 2°C since records began in 1926 (Figure CC2). Recent warm years include 2016 which was the warmest year on record for mean minimum temperatures and 2018 which was the tenth warmest year on record. 

Figure CC2: ACT mean minimum temperature anomaly (as calculated from the 1961 to 1990 average), 1926 to 2018.
Data sourced from: Bureau of Meteorology, Canberra Airport site.

Other annual temperature trends for the ACT include: 

These results demonstrate a clear warming climate trend in the ACT. The impacts of this warming are discussed in Indicator CC2: Impacts of climate change.

Observed rainfall

There is considerable year-to-year and decadal variability in annual rainfall averaged over the ACT region, with no long-term trend (Figure CC3). Over the last two decades, the Millennium Drought drove drier-than-average conditions across the ACT from 2000–2009, before being broken by the two La Niña events of 2010–2011 and 2011–2012. Recent years have been drier than average, except for 2016 which had a strong negative Indian Ocean Dipole in that year which typically results in wetter than average conditions over south-eastern Australia.

Figure CC3: ACT annual rainfall anomaly (as calculated from the 1961 to 1990 average), 1900 to 2018.
Data sourced from Bureau of Meteorology, Canberra Airport site.

Regional climate modelling has identified the most significant effects of climate change on the ACT. EPSDD, 2019, ACT Climate Change Strategy 2019–25, ACT Government, Canberra Webb, L.B. and K. Hennessy, 2015, Projections for Selected Australian Cities, CSIRO and Bureau of Meteorology, Australia These projections are dependent on the level of global greenhouse gas emissions. Projected impacts include: 

These projected changes will significantly increase climate pressures on the natural and urban environment.

Case studies