The current El Nino is growing faster than the record event of 1997/98, according to the latest statistics.
The Bureau of Meteorology says weakened or reversed trade winds have caused further warming in the tropical Pacific, with all key monitored areas more than one degree above average for 10 successive weeks.
This is two weeks longer than during 1997/98, currently the strongest event since the start of the 20th century.
El Nino is usually associated with lower rainfall and higher temperatures across many parts of Australia, increasing bushfire risk.
CSIRO Research Director Oceans and Atmosphere Wenju Cai told insuranceNEWS.com.au that while the impact of the 1997/98 El Nino was muted in Australia, there were global losses of $50 billion and 23,000 deaths.
“This El Nino is growing faster at the moment, but we do not know where we will end up,” he said.
The 1997/98 event lasted until May 1998 before switching quickly to a La Nina, the opposite condition to El Nino that brings above-average rainfall and often flooding to Australia.
This rapid reversal is a common pattern, Dr Cai says.
“Huge El Ninos will often be followed by huge La Ninas. There is a switch from one extreme to the other.
“You can imagine a situation where you have a drought, only to be followed by floods.
“The size of the El Nino can be used to predict the size of the La Nina. Quite rightly, people are focusing on the El Nino at the moment, because we will experience that impact first.”
In 1982/83 the second-biggest El Nino on record occurred. Australia was hit hard by heatwaves, the Ash Wednesday bushfires and a dust storm in Melbourne.
One upside currently is that a positive Indian Ocean Dipole (IOD), which has a major impact on bushfire risk in southeast Australia, is yet to develop.
The IOD is currently neutral, but three out of five international models suggest a positive by spring.
“All the huge El Ninos to date have been accompanied by positive IODs,” Dr Cai said.
“When the two combine then there is a severe impact on bushfire risk.
“But positive IODs usually develop in June and it has not developed yet. It may be a weak one, giving some relief.”
The US-based National Oceanic and Atmospheric Administration says last month was the warmest June on record globally, and fifth-warmest for Australia.
Dr Cai says Australia’s high temperatures and low rainfall last month are consistent with the effects of El Nino, but it is still early days in terms of predicting the impact.
“There is more than half a year of this El Nino still to go,” he said. “Let’s watch this space.”
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