Intense, frequent, record-breaking: an analysis of extreme weather in 2023

A new report by more than 30 experts analyses severe weather events across Australia in 2023.

Some climate extremes were particularly intense in 2023 and these saw a number of records broken, a new report says.

Co-written by more than 30 of Australia’s leading climate scientists and researchers from the ARC Centre of Excellence for Climate Extremes, the “State of Weather and Climate Extremes 2023” released today analyses key weather and climate extremes from last year.

“What was unusual about 2023 is how intense some of these events were and how they kept pushing records,” said Professor Andy Pitman, a leading climate scientist and Director of the ARC Centre of Excellence for Climate Extremes that is hosted at UNSW.

Prof. Pitman said that while it was challenging to determine the cause of specific extreme events, they seemed to be happening with increased frequency in 2023.

“Some of them were occurring one after the other or close to each other. These temporally and spatially compounding events had a substantial impact on our environment and were difficult for us to deal with.”

The report analyses key weather and climate extremes from 2023, including:
● The wide-ranging impacts of Cyclone Jasper in Queensland
● The South Australian September heatwave
● Early season bushfires in Queensland
● Extreme winter heat in New South Wales and an early end to the snow season in the Australian Alps
● Compounding rain and wind causing widespread damage in Hobart
● Record low sea ice extent in Antarctica
● Devastating floods in the Northern Territory and northwest Queensland.

The report is designed to help decision makers and the general public understand the complexity of climate extremes.

“Over the last few years we’ve been pulling extremes together into a narrative that provides a one-stop shop of what happened in the year,” Prof. Pitman said.

“It’s about packaging the information up in a digestible form to help people understand what’s going on in our environment.”

The report provides a description of each event and its impacts as well as an explanation that reflects scientists’ understanding of the causes.

The influence of climate drivers such as El Niño and the Indian Ocean Dipole as well as the evolution of rainfall and temperature throughout the year were also assessed in the report.

The year began with above-average rainfall in northern Australia and progressed to increasingly dry conditions in southern and eastern Australia in late winter and spring, when El Niño was declared.

Against expectations, above average rainfall was observed in December across much of eastern Australia, particularly in Northern Queensland, where residents were impacted by the intense flooding caused by Cyclone Jasper.

“We can easily get the impression that natural climate drivers such as El Niño are the dominant cause of what we observed in 2023, but that’s not true,” Prof. Pitman said.

“El Niño does not guarantee that eastern Australia will be hot and dry, rather it influences the probability of hotter and drier conditions.”

Overall, 2023 was the 8th hottest year on record in Australia, with temperatures 0.98°C above the 1961-1990 average. Winter was the warmest on record since observations began in 1910, and September was the driest ever recorded.

Globally, 2023 marked the hottest year on record and a year of extremes. Canada’s wildfire season in June was unprecedented with 18.4 million hectares burnt, and the heatwaves over Europe contributed to many national and global temperature records tumbling in July. The report provides an overview of some international events that took place in 2023.

“There’s plenty of places around the world where events are becoming hard to survive,” Prof. Pitman said.

“What scientists bring to the table is more and more evidence of what we already know. We need to act based upon observations and existing knowledge. The actions are straightforward: stop emitting carbon and invest heavily in adaptation.”

As for what will happen in terms of extreme events in 2024, this remains uncertain, Prof. Pitman said.

“This year appears to be leaning towards a weak El Niño or more neutral La Niña conditions. It is likely to be a warm year. However, how extreme events will be expressed regionally over Australia is hard to predict.”

Read more: What we know about last year’s top 10 wild Australian climatic events – from fire and flood combos to cyclone-driven extreme rain