AUSTRALIA’S weather bureau has confirmed that an El Niño and a positive Indian Ocean Dipole are under way, indicating warmer and drier conditions are more likely for south-eastern Australia.

In its latest Climate Driver Update, the Bureau of Meteorology said declaration of the events, and their concurrence over spring, have reinforced the bureau’s long-range rainfall and temperature forecasts.

These forecasts continue to predict warmer and drier conditions for much of Australia over the next three months.

The confirmation of an established El Niño increases the likelihood that the event will be sustained through the Summer period, the bureau said.

The bureau today said oceanic indicators firmly exhibit an El Niño state.

Central and eastern Pacific sea-surface temperatures continue to exceed El Niño thresholds and models indicate further warming of the central to eastern Pacific is likely.

Broadscale pressure patterns over the tropical Pacific reflect El Niño, with the 90-day Southern Oscillation Index (SOI) at −7.7.

Recent trade-wind strength has been generally close to average, but was slightly weaker than average across the tropical Pacific in August 2023 for the first time since January 2020, the bureau said.

The bureau said overall, there are signs that the atmosphere is responding to the pattern of sea-surface temperatures in the tropical Pacific, and coupling of the ocean and atmosphere has started to occur.

“This coupling is a characteristic of an El Niño event and is what strengthens and sustains an event for an extended period.

“Climate models indicate this El Niño is likely to persist until at least the end of February.”

The bureau said El Niño typically leads to reduced Spring and early Summer rainfall for eastern Australia, and warmer days for the southern two-thirds of the country.

“A positive Indian Ocean Dipole is under way.

“The Indian Ocean Dipole index is +1.25°C for the week ending 17 September,” the update said.

“This is its fifth week above the positive IOD threshold (+0.40 °C).

“The longevity of this trend, combined with the strength of the dipole being observed and forecast, indicate a positive IOD event is under way.”

The bureau said all models predict this positive IOD will persist to at least the end of spring.

A positive IOD typically leads to reduced spring rainfall for central and south-east Australia.

When a positive IOD and El Niño occur together, their drying effect is typically stronger and more widespread across Australia, the bureau said.

The Madden–Julian Oscillation is currently weak and is forecast to remain weak over the coming week.

The Southern Annular Mode index is currently negative and is expected to remain negative for at least the coming week, before a possible return to neutral late in September.

During spring, a negative SAM is associated with decreased rainfall across parts of the east in both NSW and Victoria, and increased rainfall over western Tasmania, the bureau said.

The bureau’s long-range forecast for Australia indicates warmer and drier than average conditions are likely across most of southern and eastern Australia from October to December. The bureau’s climate model takes into account all influences from the oceans and atmosphere when generating its long-range forecasts.

Farmer group urges economy-wide climate action

Farmers for Climate Action today calling for urgent action to limit climate change after the declaration that farmers are officially facing an El Niño weather pattern after three years of La Niña.

Farmers for Climate Action member Peter Lake farms near Grafton on New South Wales’s north coast, that is officially in drought conditions after battling floods 12 months ago.

Mr Hall said conditions turned from mud to concrete in a couple of weeks and suddenly everything was just dry.

“From flood to drought, climate change is making the changes more extreme,” he said.

Farmers for Climate Action chair Brett Hall, in Tasmania’s Derwent Valley, said many farmers were concerned about the possibility of warmer, drier conditions and increased weather variability for eastern Australia this spring and summer.

“Although some farmers have had reasonable conditions recently, we know things can change in a few months.”

Mr Hall said farmers are always looking three steps ahead to the next event, but there are limits to their adaptation.

“While we adapt and mitigate on-farm, we need to know the rest of the economy is doing its bit to reduce emissions and tackle climate change, which is causing more frequent and severe weather events.”

Farmers for Climate Action represents 8000 farmers and hosted an El Niño explained webinar in July. Click here to see that presentation.

Source: Bureau of Meteorology, Farmers for Climate Action