The Actuaries Institute’s latest Australian Actuaries Climate Index has revealed significant temperature increases during the summer of 2023/24.
Both high and low temperatures in Australia rose above usual levels, particularly in the northeast, from December to February. The index, which tracks extreme weather frequency and changes over time, recorded elevated temperatures in this region.
In particular, the East Coast (South) and Wet Tropics cluster regions of New South Wales and Queensland registered their third and fourth-highest high-temperature index values on record. The eastern parts of Queensland, NSW, and Victoria saw their highest low (minimum) temperature index values.
With warmer minimum temperatures becoming more frequent due to global warming, the Actuaries Institute said risks related to pests and diseases could escalate, impacting agriculture.
Meanwhile, extreme rainfall levels affected northeastern Queensland, as Cyclones Jasper and Kirrily struck the region over summer. This resulted in the index’s 34th consecutive positive value, reflecting that the frequency of extreme weather remains higher than the baseline set between 1981 and 2010.
Rade Musulin, the lead collator of the index, said persistent higher temperatures could have significant impacts on both ecosystems and land use.
“Insects and pathogens may change their geographic scope, particularly if higher minimum temperatures persist into winter, because they will not be killed off as early as they normally would,” he said. “Those warmer temperatures can also impact agricultural production and people’s health, particularly because it is harder to sleep if it does not cool down after a sweltering day.”
The Bureau of Meteorology identified last summer as the third-warmest recorded, predicting an increased likelihood of elevated temperatures through May and July.
Musulin highlighted the potential risks if summer’s warmer conditions extend into autumn and winter.
“We need to be on guard if these warmer temperatures from summer continue into autumn and winter,” he said.
Although Australia is currently in an El Niño phase known for dry and hot conditions, intense rainfall in Queensland was likely influenced by warmer sea surface temperatures, which drove higher moisture into the atmosphere.
“When you have warmer temperatures and high sea surface temperatures you get more precipitation. This can contribute to bigger fuel loads in the bush, which combined with factors such as insect damage to trees, can raise the risk of bushfires next summer,” Musulin said.
The index focuses on extreme weather conditions exceeding the 99th percentile during the 1981-2010 reference period. This metric is more relevant to the insurance industry than averages, as it correlates more directly with damage, tracking patterns in high and low temperatures, rainfall, wind, and sea levels.
