An unusual trio of climate patterns brought heavy rainfall and an exceptionally wet but warm year to Australia in 2022, with temperatures remaining higher than average against the backdrop of human-induced climate change.
The main climatic influences on Australia in the past year included the La Nina weather pattern and greater-than-average rainfall, according to the Bureau of Meteorology’s annual climate statement released on Wednesday.
The big picture makes sense of the unsettled, damp weather across much of Australia in the past 12 months.
La Nina persisted through summer 2021 to 2022, eased during autumn, returned in early September and continued through to the end of the year. This was the third year of the La Nina climate pattern – back-to-back La Nina events are not uncommon, but three La Nina events in a row is more unusual.
It was joined by a “negative” Indian Ocean Dipole in winter and spring, which also increases rainfall, and a persistent “positive” phase of the Southern Annual Mode, which is associated with storms and cold fronts that move from west to east, bringing rainfall to southern Australia.
These climate drivers combined, and rainfall in Australia was about 25 per cent above the 1961 to 1990 average – at 587.8 millimetres – meaning 2022 was the ninth-wettest year on record since 1900 for Australia.
“It was the trio of wet-phase climate drivers that stood out in 2022 that caused unusually prevalent easterly winds and drove lots of rainfall over eastern Australia,” said meteorologist Ben Domensino from forecasting service Weatherzone.
There was also a lack of extreme heat in Sydney, for example, which had no days over 32. In Melbourne, to date, it has been more than 1100 days since the temperature last reached 40 degrees at the Olympic Park weather station. That’s the longest stretch below 40 degrees for about 50 years.
There was intense, persistent rainfall across much of eastern Australia, with regional riverside communities in Victoria, NSW and Queensland bearing the brunt of severe flooding and the most significant floods occurring at the beginning and end of 2022.
In many parts of the Murray-Darling Basin, the flooding occurred over prolonged periods, or on multiple occasions, continuing to affect communities throughout October and into November.
Rain delayed play at the Australian Open in JanuaryCredit:Getty Images
However, rainfall was below average for western Tasmania, much of the north of the Northern Territory and the far south-west of Western Australia.
Australia’s national mean temperature was half a degree warmer than the 1961-1990 average, and it was especially warm in the tropics, with severe to extreme heatwave conditions affecting parts of the north and the west during the year.
In addition to the influence of natural drivers, Australia’s climate is increasingly affected by global warming. It has warmed on average by 1.47 degrees (give or take 0.24 degrees) between when national records began in 1910 and 2021, with most of the warming occurring since 1950.
The sea temperature around nearly all of Australia as a whole was much warmer than average, and the highest on record across large areas of the waters to the north of Australia, across much of the Arafura Sea and the Coral Sea.
The warm waters around Australia influence our climate as they act as a source of moisture through evaporation, which increases humidity, cloudiness and the chance of rainfall.
To the south of Australia, the net sea-ice extent around Antarctica in February 2022 was the lowest on record, a finding based on near-continuous satellite imagery since 1979.
Australia’s weather will become even more chaotic in coming years and decades, the bureau found in its recent State of the Climate report, piling pressure on the federal government to increase its climate targets.
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