The presence of a third consecutive La Nina has resulted in Australia experiencing its coolest year since 2012, but temperatures still remain well above the long term average.
The Bureau of Meteorology (BoM)’s Annual Climate Statement for 2022 reports that Australia experienced the ninth wettest year on average, and temperatures were 0.50°C above average.
Since Australia has warmed by 1.47°C overall since 1910, give or take a quarter of a degree, this makes 2022 one of the cooler years in recent memory.
But two of Australia’s biggest climate drivers – La Niña and a negative Indian Ocean Dipole – were in phases that would normally provoke a cooler and wetter than average year. The warmth of 2022 can yet again be chalked up to climate change.
Australia in 2022: key climate numbers
- Ninth wettest year on record overall
- Wettest spring on record in south-eastern Australia
- Temperatures were 0.50°C above average overall: coolest year since 2012
- Equal-22nd warmest year on average, despite all major climate drivers being in their cooler phase
- Average number of tropical cyclones, but significantly higher than average number of weaker tropical storms
While south-western WA and western Tasmania both experienced below average rainfall, the rest of the country – and particularly the southeast – had a very wet 2022.
The year was bracketed by two La Niña events, phenomena in the Pacific Ocean which generally bring more rainfall and lower temperatures to eastern Australia. There was also a negative Indian Ocean Dipole, which (as opposed to a positive Indian Ocean Dipole) also brings more rain to the Top End and southern Australia.
The summer of 2022-23 marked the third La Niña in a row, and brought rainfall and flooding with it to eastern Australia.
BoM Senior Climate Risk Specialist Dr Stephanie Jacobs said in a webinar yesterday that triple La Niña events had occurred a few times in the last century – but they’d never seen a fourth in a row in their records.
“The way the climate models are looking right now, it’s unlikely that we’re going to see a fourth.”
Jacobs added that a pattern in the Southern Ocean played a major role in rainfall, particularly during the second half of the year. This pattern was the Southern Annular Mode, which describes the band of wind that circles Antarctica. It was mostly in a positive phase in 2022.
“A positive phase is when this band of winds has moved further south. What happens in terms of the climate, in spring and summer, is that this actually means more rainfall – because all this moisture from the tropics can come down.
“Rain-bearing systems from the east as well come in and cause wetter conditions for a lot of southeastern Australia, but notably, less rainfall in western Tasmania.”
Beyond the extensive flooding seen in much of the country, this rainfall led to many water storage systems reaching capacity, and a general replenishment of groundwater.
Dr David Wilson, a hydrologist at the BOM, pointed out that Queensland’s Wivenhoe Dam, for instance, went from 57% full to over 180% full in five days over February.
Jacobs said that it’s still too early to tell what the weather patterns will bring next summer – and therefore, whether to prepare for floods, cyclones, or bushfires.
But, the BOM is predicting a drier and warmer than usual autumn, and April to June will also likely be drier than average.