THE world is heading into a major drought-bringing El Nino event, which will lift global temperatures and lead to bushfires and water shortages in eastern Australia, climate scientists have confirmed.
Fairfax Media understands Australia’s Bureau of Meteorology will announce on Tuesday the El Nino event is all but certain.
Sea-surface temperatures in the central and eastern Pacific are recording anomalies of more than 1 degree, a combination that has not previously been seen in weekly data going back to 1991, according to a bureau forecaster.
Australia’s measure of El Nino thresholds is sustained warmth of sea-surface temperatures of 0.8 degrees above average in the key regions surveyed, a higher bar to clear than set by the US and some other agencies.
“You can see a warming in the eastern Pacific, which looks to be a classic (El Nino) event,” said Agus Santoso, an El Nino modeller at the University of NSW’s Climate Change Research centre.
Scientists, though, are surprised that the build-up of unusual warmth in the eastern Pacific compared with the west is happening so early in the year.
“It’s quite rare — this is an interesting one,” Dr Santoso said.
In typical El Nino years, the usual easterly trade winds stall or even reverse in winter or later, dragging rainfall eastwards away from Australia and also south-east Asia.
Droughts tend to deepen and spread and bushfire seasons are more active than normal.
A study by the bureau of 12 strong El Nino years since 1905 found rainfall declines were most evident in winter and spring — key agricultural seasons.
The hardest hit areas cover most of NSW and parts of southern Queensland, while almost all of the eastern states have significantly reduced rain.
An El Nino event this year would be bad news for areas also suffering serious or severe rainfall deficiency.
A bureau drought report out this week identified such areas over the past 30 months to include much of inland Queensland, western Victoria and north-central NSW — some of which are already receiving federal and state aid.
The bureau declined to say that its El Nino report would confirm the event.
“The tropical Pacific has continued to warm in the past week and all indices now exceed 1 degree,” Andrew Watkins, head of the bureau’s climate prediction services, said.
It’s the early start to the process, though, that has climate scientists concerned the planet may be on course for a particularly strong El Nino event.
“If it peaks in winter then dies off it’s interesting,” Dr Santoso said. “But if it keeps going up and peaks in summer, that could potentially be a big El Nino.”
Wenju Cai, a leading climate modeller at the CSIRO, said experts were predicting a strong El Nino a year ago but sustained westerly winds failed to eventuate. As a result, the atmosphere did not “couple” with, or reinforce, the warming trends in the oceans.
“Last year at this time, we didn’t see the (westerly) winds,” Dr Cai said. “This time, we see the strong westerly winds all along the equator.”