Indicator assessment
CONDITION
TREND
DATA QUALITY
Climate change is already impacting on the ACT’s community, economy, and the natural environment. Observed changes include increases in tree mortality, soil erosion, air pollution, impacts on water quality, recreational water closures, and extended periods of reduced river flows and water resources. The ACT’s warming climate, combined with periods of below average rainfall, is increasing fire risk and was a significant factor in the severity of the 2020 bushfires.
CONDITION
Environmental condition is healthy across the ACT, OR pressure likely to have negligible impact on environmental condition/human health.
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.
Environmental condition is under significant stress, OR pressure likely to have significant impact on environmental condition/ human health.
Data is insufficient to make an assessment of status and trends.
TREND
DATA QUALITY
Adequate high-quality evidence and high level of consensus.
Limited evidence or limited consensus.
Evidence and consensus too low to make an assessment.
Assessments of status, trends and data quality are not appropriate for the indicator.
Environmental impacts
The warming associated with climate change has already affected the ACT’s ecosystems and biodiversity, human health and livelihoods, and changed the intensity and frequency of heatwaves, droughts, storms, and floods.
Attributing environmental changes to climate change alone is difficult due to the range of factors that affect the environment. However, data used in this report suggest the following impacts from climate change:
- Despite the higher than average rainfall from 2020 to 2022, long term projections suggest extended periods of lower than average rainfall leading to reduced water for the environment and for the ACT’s water resources. It is highly likely that the ACT will again experience reduced inflows to water storages. For example, all but two years were below the long-term average for inflows between 2001–02 and 2019–20. The total inflows during 2018–19 were the lowest since records began in 1912 (see Human settlements — Indicator HS5: Water resources).
- Increased tree dieback across the ACT. For example, observations in Namadgi National Park prior to the 2020 bushfires showed significant dieback in eucalypts due to the unprecedented hot and dry conditions (see Biodiversity — Indicator B4: Native vegetation extent and condition).[4] There is also an increase in the mortality of urban trees due to increasing temperatures and dry periods. This may suggest that climate conditions in the ACT region are no longer suitable for some tree species.
- Longer periods of higher temperatures and reduced rainfall have led to an increasing number of consecutive fire seasons with elevated fire severity risk in the ACT, as well as fire seasons that are starting earlier and lasting longer. Extended periods of elevated fire severity increase the chance of a significant bushfire such as the 2020 fires which occurred after eight years of elevated risk conditions. Such conditions also increased the intensity and size of the 2020 bushfires (see Fire — Indicator F2: Fire risk and 4. Bushfires in the ACT).
- The increased need for fuel reduction burns undertaken to manage the risk of bushfires can impact on air quality due to smoke (see Air — Indicator A1: Compliance with air quality standards).
- Increased occurrence of dust storms caused by the loss of ground cover vegetation and greater wind strength (see Air — Indicator A1: Compliance with air quality standards).
- The loss of ground cover vegetation caused by heat and drought, combined with more severe storms, is increasing the severity of soil erosion and degrading soil health (see Land — Indicator L2: Land health).
- A warming climate and increased intensity of storms is increasing impacts on water quality through elevated water temperatures, nutrients and sedimentation. This has led to more frequent cyanobacterial blooms in Canberra’s lakes, reducing amenity and recreational activities, and has also impacted on the ecosystem health of other waterways including urban and non-urban rivers and creeks (see Water).
There will be many other impacts which are not captured by data used in this report. This is particularly the case for subtle changes that occur over long periods. For example, it is widely accepted that climate change is having a significant impact on terrestrial and aquatic ecosystems and the biodiversity they support. The repercussions of climate change on human health and wellbeing are also well documented.[5]
It is also difficult to determine climate change impacts at the local level, particularly for the natural environment. This is because the severity of changes depends on a range of factors including landscape types, elevation, and the sensitivity and resilience of ecosystems. This means that the implications of climate change will differ across the ACT with some areas and ecosystem types more affected than others.
Climate change and the 2020 bushfires
The severity and size of the ACT’s 2020 bushfires were a consequence of climate change which is contributing to more severe fire seasons that are starting earlier and lasting longer. There were extreme temperatures over the 2019–20 summer with 4 January recording the ACT’s hottest day on record at 44°C. The mean maximum and minimum temperatures over the summer were the third warmest on record. In addition, the ACT was experiencing the lowest rainfall deficit on record, along with much of NSW. The combination of heat and low rainfall provided optimum conditions for the bushfires, for both temperature and dry fuel loads.
Climate conditions led to concerning fire severity risk conditions for the ACT prior to the fires. The risk conditions were particularly elevated in the month leading up to the Orroral Valley fire and for the first days of the fire. Fire severity risk conditions included two catastrophic and two extreme risk days, seven severe days, ten very high and nine high risk days. Such conditions significantly increased the severity and spread of the Orroral Valley fire.
The impacts of the 2019–20 bushfire season on the ACT’s community, environment and biodiversity are discussed in 4. Bushfires in the ACT. The future risk of bushfire in the ACT is also discussed.
Data gaps
More comprehensive data is required on the impacts of climate change on natural ecosystems, the urban environment and human health to improve knowledge, adaptation and resilience.
← Previous