Much of the country received above-average rainfall and experienced large-scale flooding in 2022, especially over inland New South Wales, southern Queensland, and northern Victoria. The saturated ground will likely support enhanced vegetation growth. This increase in fuel loads, together with warmer and drier conditions over the coming months, is likely to result in above-average fire potentials across central, western, and southern Western Australia, southern Northern Territory, southern Queensland, and inland New South Wales.
Bushfires are integral to the Australian environmental landscape. Many native plants are fire-prone, and some depend on fire to regenerate. Bushfires start due to a combination of dry fuel in the form of leaf litter or other organic debris and an ignition source (generally lightning strikes or human activity). The speed at which the fires spread and the intensity at which the fires burn depends on wind speed, ambient temperatures, slope angle, the amount of fuel available, and the amount of moisture in the fuel.
Summer 2023 Forecast
Figure 1 forecasts areas anticipated to have higher than average wildfire risk and lower than average risk.
- Above-normal fire potentials are forecast across central western and southern Western Australia, southern Northern Territory, southern Queensland and inland New South Wales due to increased fuel loads as a result of significant rainfall as well as across western Tasmania due to a dry spring.
- Below-normal fire potentials are forecast across eastern New South Wales, central and northern Victoria, and Australian Capital Territory due to increased fuel moisture, the likely continued rainfall, and reduced fuel loads following the severe 2019-20 bushfire season.
The bushfire season typically runs December-May in southern Australia, May-October in northern Australia, and August-March in central Australia. Southeastern Australia, including southeastern South Australia, Victoria, and southern New South Wales, is one of the most fire-prone areas worldwide. Figure 2, below, shows the intensity and distribution of bushfires 2016-2020.
Continued above-average rainfall over New South Wales and Victoria resulted in flooding across many parts of the states during 2022. In New South Wales, very high soil moisture content due to the persistent rainfall will continue to enhance grass growth, adding to the existing high fuel loads. The persistent flood conditions are likely to lead to below-average fire activity in the affected regions early in the summer season. The forecast return to normal rainfall conditions as the summer progresses will likely cure the grass fuels and cause them to become more susceptible to fire. This will lead to above-normal fire potentials later in the season, especially in western parts of the state. Although recent rainfall has aided in the recovery of the areas burned in the severe 2019-2020 bushfire season, fuel loads remain low and wet conditions are likely to lead to below-average fire potentials in the area.
In Victoria, forecast models indicate an increased potential for above-average rainfall, especially in central and eastern Victoria through the summer; fire activity is likely to be limited to foothill and wet forests. Drier forests, woodland, and heathlands could support fire activity with the onset of hot and dry conditions. The significant grass fuel growth in paddocks and roadsides is likely to continue but grass curing is progressing slower than average, likely leading to below-average fire potentials early in the summer, with the risk of fires increasing as summer progresses and curing advances. The north and west of the state will therefore likely see increasing fire potentials from mid-summer.
The high amount of grass fuel in Queensland is tempered by significant soil moisture due to the persistent wet conditions. If drying and curing conditions increase, above-average fire potentials are possible in Maranoa and Channel Country.
Above-average temperatures and average to below-average rainfall are forecast over Western Australia during the summer. Higher-than-normal fuel loads and the forecast warm and dry conditions mean that above-normal fire potentials are likely in the central western parts of the state, including the Pilbara, Carnarvon, Gascoyne, and Murchison bioregions; southern Western Australia, including the Jarrah Forest Bioregion, will also see an increased potential due to low rainfall and below-average soil moisture.
Above-average fire potentials are forecast over the Alice Springs and parts of Tanami region in Northern Territory, including parts of the Macdonnell Ranges, Burt Plain, and Finke bioregions as there is sufficient fuel for large fires to form.
Dry conditions over recent months have resulted in reduced soil moisture across western Tasmania while above-average rainfall in eastern Tasmania has increased soil moisture and enhanced grass fuel growth. La Nina conditions are forecast to persist, bringing greater than average rainfall to northern and eastern Tasmania. The rainfall will likely delay the curing of grass fuels, resulting in below-normal fire potentials for the east coast of the state. Below-average rainfall and above-average temperatures are forecast over western Tasmania through at least early 2023; above-normal fire potentials are likely due to the greater-than-normal flammability of fuels. Lightning strikes may also ignite fires in the area.
Disruptive Impact of Bushfires
Bushfires can result in loss of life, property damage, economic losses, and infrastructure damage. Power outages are possible in places due to damaged substations and transmission lines or intentional power cuts to prevent infrastructure damage or help prevent the spread of fires.
Extensive soil erosion is possible across burn scars during bouts of rainfall due to loosened soil and an increase in runoff from the lack of interception by trees and foliage.
Supply chain disruptions are possible, especially if bushfires burn across highways and roads or approach large population centers. Bushfires can also lead to evacuations, road closures, and ground transport diversions. Disruptions to arterial roads are possible, and the scarcity of alternative routes in some areas means that significant transport disruptions are possible at times. While authorities are experienced in minimizing the potential impact, roads in remote regions are likely to be disrupted for longer periods than urban roads due to their relative inaccessibility. Authorities could close routes in bushfire complexes and evacuate communities due to fire activity and the needs of response operations. Traffic flows could also be disrupted after authorities lift evacuation orders during reentry periods.
Low visibility from smoke and possible ashfall could contribute to traffic delays and congestion and prompt short-notice flight disruptions if bushfires occur near airports. Railways can also experience occasional cancellation of services and long delays.
Many warehouses, factories, and other supply chain-related businesses tend to be located in the suburbs with a higher likelihood of being affected by bushfires as compared to city centers. Bushfires can destroy crops and livestock, resulting in losses. Businesses are also likely to be adversely affected by the supply chain disruptions especially if they require transportation of perishable goods.
Health Impacts of Bushfires
The acute effects on the individual of smoke inhalation from bushfires typically lead to a surge in people presenting to emergency departments with asthma attacks, exacerbations of chronic bronchitis and emphysema (COPD), eye and skin irritations and also with cardiac conditions as a result of the strain on the whole circulatory system.
There are also concerns about the long-term effects of acute episodes of smoke inhalation. Fires release multiple pollutants including carbon dioxide and monoxide and chemicals such as benzene that produce deleterious effects on the environment. However, air quality experts are most concerned about the tiny particles, referred to as PM2.5. These are fine particles that are 2.5 microns or less in diameter (less than the diameter of a human hair) and can travel deep into the respiratory tract, reaching the lungs and entering the bloodstream.
According to a study published in the New England Journal of Medicine in 2020, an increase in these tiny particles is associated with a higher risk from all medical causes for up to four days after a population is exposed. The findings of the US Environmental Protection Agency (EPA) risk assessment focused on the increase in all-cause mortality, mortality due to ischemic heart disease, and mortality due to lung cancer: “exposure to increased levels of PM2.5 is also causally linked to numerous other adverse health outcomes, including long- and short-term cardiovascular events, respiratory illnesses, death from cancers other than lung cancer, and nervous system diseases, including dementia. Additional health concerns, such as adverse pregnancy and birth outcomes, are associated with particulate air pollution, though the evidence of causality is weaker”.
Minimize risks before and during exposure to bushfires, download Crisis24’s advice sheet: Personal Safety Before and During Wildfires.
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