​La Niña shows signs of declining strength

La Niña continues in the tropical Pacific, but some indicators show signs of declining strength, according to the Bureau of Meteorology. La Niña typically increases the chance of above average rainfall for northern and eastern Australia during summer.

Models suggest that ocean temperatures may reach ENSO-neutral levels during January or February 2023, and remain at neutral levels until at least April.

Sea surface temperatures remain warmer than average in the western Pacific, much of the Maritime Continent, and around northern Australia, particularly in the Coral Sea. Warmer Australian waters, especially in the tropics, can result in greater evaporation, humidity, cloudiness, and rainfall.

Climate change tips the balance

Climate change continues to influence Australian and global climates. Australia’s climate has warmed by around 1.47 °C in the period 1910–2021. There has also been a trend towards a greater proportion of rainfall from high intensity short duration rainfall events, especially across northern Australia.

The State of the Climate Report 2022, released by CSIRO and the Bureau of Meteorology, found changes to weather and climate extremes are happening at an increased pace across Australia.

The director of CSIRO’s Climate Science Centre, Dr Jaci Brown, said concentrations of greenhouse gases, such as carbon dioxide, are at the highest levels seen on Earth in at least two million years.

“The concentrations of greenhouse gases in the atmosphere are continuing to rise, and this is causing Australia’s climate to warm,” Dr Brown said, adding that the report documents the continuing acidification of the oceans around Australia, which have also warmed by more than one degree since 1900. 

“The warming of our oceans is contributing to longer and more frequent marine heatwaves, and this trend is expected to continue into the future,” Dr Brown continued. “We’re seeing mass coral bleaching events more often, and this year, for the first time, we’ve seen a mass coral bleaching on the Great Barrier Reef during a La Niña year.”