Expert discusses La Niña and El Niño cycles effects on Australia


The last El Niño was 6-7 years ago, but elapsed time can’t on its own be a guarantee of one this year. Neutral ENSO conditions are another option. As usual an assertion about warming from greenhouse gases is thrown in, with no evidence to back it up.
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Climate models indicate La Niña is on the way out, with El Niño conditions expected later this year, claims Phys.org.

CSIRO Climate Scientist Dr. Wenju Cai explains what this means for Australia’s weather and how changing conditions will affect the country.

Is La Niña really on the way out? What do the climate models tell us?

We are in the mature season of the current three-consecutive La Niña years. During the three years, heat has been stored in the equatorial Pacific Ocean.

There is no precedent for four-consecutive La Niña years. Models that predict the El Niño Southern Oscillation (ENSO) cycles are indicating a demise of the current La Niña condition.

Does this mean El Niño is on the horizon?

With so much heat charged in the equatorial Pacific, an El Niño is readily triggered by relaxation of the trade winds over the equatorial Pacific. Many models are predicting an El Niño by the northern hemisphere summer months. ENSO predictions are more accurate after June, when noise is low. Several previous three-consecutive-year La Niña events, such as the 1973–1975 or 1983–1985 events, were followed by an El Niño.

What will El Niño mean for Australia?

During El Niño, drought occurs over eastern and north-eastern Australia in spring and summer. During winter and spring, a developing El Niño often drives an Indian Ocean Dipole (cooling in the eastern Indian Ocean), inducing droughts over southern Australia in the rain seasons.

Overall, Australia experiences drought, higher temperatures, bushfires and more intense and frequent heatwaves on land and sea, and these extremes are likely exacerbated by warming from increasing greenhouse gases.

Droughts and heat waves cause damage to Australia’s iconic ecosystems, such as the drying of the Murray and Darling Rivers, and coral bleaching on the Great Barrier Reef. Drought in the Murray Darling Basin and the drying Murray and Darling Rivers affect agriculture and mining activities, often reducing economic outputs by tens of billions of dollars.

Bushfires kill and displace wild animals, and affect them in the aftermath by causing starvation, lack of shelter and predator attacks. One estimate suggested that the 2019/20 Black Summer Fires affected over three billion wild animals, most of which likely perished.

El Niño and La Niña explained

Both El Niño and La Niña are known as climate phenomena. The oceans switch between these states roughly every two to seven years, depending on the wind and ocean conditions across the equatorial Pacific Ocean between Australia and South America.

El Niño is known as the warm phase and La Niña the cold phase, but it’s also possible to be in a neutral ENSO phase.

Full article here.

via Tallbloke’s Talkshop

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January 7, 2023 at 03:47AM

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