Australian summers bring higher disease risk

High temperatures could impact agricultural production and health.

The Australian Actuaries Climate Index for summer 2023/24 indicates that both low and high temperatures were unusually warm. Additionally, extreme rainfall and wind were prevalent in the northeast. 

The index, which tracks the frequency of extreme weather conditions over time, recorded elevated temperatures in the northeast from December to February. 

The East Coast (South) and Wet Tropics regions of NSW and Queensland had the third and fourth-highest high-temperature index values on record. Eastern parts of Queensland, NSW, and Victoria also recorded their highest low (minimum) temperature index values to date. 

Higher minimum temperatures, often overlooked, can increase the risk of pests and diseases spreading, impacting agriculture in Australia.

The extreme rainfall index was high in northeastern Queensland, affected by Cyclones Jasper and Kirrily, marking the 34th consecutive positive value for the index, above the average for 1981-2010. 

Rade Musulin, the lead collator of the index, emphasised the need to focus on future-proofing building codes and land use policies and to consider the ecological impacts of warmer temperatures. 

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“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.” Musulin added.

Last summer was the third warmest on record, according to the Bureau of Meteorology, which predicts a likelihood of unusually high temperatures from May to July. Musulin highlighted the importance of vigilance if these temperatures continue into autumn and winter. 

Despite being in an El Niño cycle, typically associated with hot, dry conditions, significant rain in Queensland was likely influenced by elevated sea surface temperatures, increasing air moisture. 

Warmer temperatures and high sea surface temperatures lead to more precipitation, contributing to larger fuel loads and a higher risk of bushfires, as seen with pine beetle infestations in Canada linked to extreme wildfires.