'Warmer and wetter': Bureau highlights contrasting conditions

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The Bureau of Meteorology says Australia experienced “warmer and wetter” conditions last year as a flood-inducing La Nina held sway, particularly in parts of eastern states, while warmer conditions were felt across northern Australia and the west coast.

In its Annual Climate Statement, the Bureau says the national temperature average was 0.5 °C above the 1961-90 average, the coolest since 2012.

The mean average maximum temperature was higher in Tasmania, WA and northern Australia, but an “exceptionally wet year for the mainland south-east” saw below average maximum temperatures for NSW, southern Queensland, and parts of SA. Mean average minimum temperatures were above average across the country.

The national rainfall average was 26% above the 1961-90 average at 587.8mm, which marked the ninth wettest year in Australian recorded history. NSW and Victoria recorded their second and fifth highest average rainfall years since records began.

The record rainfall resulted in devastating flooding across NSW, Victoria and Queensland, as an “uncommon” three consecutive La Nina events and a negative Indian Ocean Dipole (IOD) influenced weather conditions.

“When La Nina and negative IOD conditions combine, the likelihood of above average rainfall over Australia is further increased, particularly for the eastern half of the continent,” the Bureau said.

Annual Sea Surface Temperature (SST) was the warmest on record for the region as a whole, at 0.80 °C higher than 1961-90 averages and above annual global SST.

Areas around the Tasman, Arafura and Coral Seas, as well as the Western Pacific, recorded their highest warmth level in events linked to the negative IOD and repeated La Nina events.

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“These warm waters around Australia also have an influence on our climate as they act as a source of moisture through evaporation, increasing humidity, cloudiness, and the chance of rainfall,” the Bureau said.

“When the synoptic systems align, features such as north-west cloud bands can draw tropical moisture far into the southern and eastern states of Australia, such as happened during March 2022, contributing to heavy rainfall over a wide area.”

The Antarctic sea ice cover, which the bureau says is a “key indicator of the health of the southern polar region and the global climate,” reached a new low last year. However, it notes that net values did not “fully reflect the regional variability”.

“There are several factors that contribute to the changing extent of Antarctic sea ice, including ocean and atmospheric temperature, winds, ocean currents and salinity,” the bureau said.

“The loss of sea ice around Antarctica has significant implications for the global climate and the ecosystems that depend on it. As sea ice retreats, it exposes darker ocean water to sunlight, which can absorb more heat and contribute to warming.”

Click here for the annual statement.