| El Nino weather pattern not all doom for Australian farmers |
A STRONGER El Nino weather pattern doesn’t necessarily mean a failed spring for Australian farmers, according to climate experts.
Forecasters across the globe say a strong El Nino — whereby warmer sea surface temperatures in parts of the Pacific Ocean can result in hotter temperatures and reduced rainfall in parts of eastern Australia — is forming and is expected to last until next autumn.
Some experts say it is the worst in decades while US scientists have labelled it “the Godzilla” of El Ninos.
“It is not the words I would use but at the moment it is heading towards medium to strong,” University of Melbourne school of earth sciences Professor David Karoly said.
Bureau of Meteorology
climatologist Blair Trewin said while the El Nino was already “the strongest since 1997 in sea-surface temperature terms” a stronger pattern “doesn’t necessarily mean a stronger impact on Australia”.
Dr Trewin pointed to the previous worst El Nino pattern in 1997, which he said had a “fairly modest” impact on Australian rainfall.
“Some El Nino events which were much-less significant events in how far the ocean temperatures were above normal in the Pacific, like 2002 and 2006, had much more widespread dry conditions in Australia,” he said.
Dr Trewin said El Nino conditions were already evident and while “it may not really feel like it at the moment” large swathes of Victoria — particularly in the central and western parts of the state — had been “tracking significantly below normal rainfall for quite some time now”.
“It has not really been a case of any individual month or season being dramatic but we’ve just strung together a long sequence of months with below-normal rainfall,” he said.
Prof Karoly said the El Nino was expected to lead to drier conditions in areas inland of the Great Dividing Range in Victoria, NSW and Queensland.
He said regions “that have been dry for the last six to 12 months” would be the worst affected. “They haven’t got the moisture in the soil already,” he said.
SQP Grain Mallee grain merchant Brad Cullen said farmers weren’t particularly worried about El Nino at this stage.
“Growers, while they’ve certainly heard a lot about El Nino during the whole season, are more interested in the conditions on the ground — the bigger picture stuff,” Mr Cullen said.
“If you looked over the border into NSW, you’d say ‘what El Nino?’.”
WHAT IS AN EL NINO?
AN EL Nino occurs when sea surface temperatures in the central and eastern tropical Pacific Ocean become substantially warmer than average, causing a shift in atmospheric circulation, the Bureau of Meteorology says.
“The most typical El Nino impact on climate is that you get below-normal rainfall in the second half of the year in eastern Australia,” BOM climatologist Blair Trewin says.
HOW SEVERE IS THIS ONE?
IN TERMS of sea surface temperatures, the current El Nino is shaping up as the worst since 1997.
“It already is a strong El Nino and is forecast to remain that way,” Dr Trewin said. “Although it may not really feel like it at the moment, quite a lot of Victoria has been tracking (with) significantly below normal rainfall for quite some time now.
In some regions, particularly northcentral Victoria and in the Wimmera, (rain) has been significantly below normal.”
WHAT DOES IT MEAN FOR YOU?
A STRONGER El Nino pattern doesn’t necessarily equate to a much-drier Australia. “(In the last severe El Nino in 1997) the impact on Australian rainfall was actually fairly modest,” Dr Trewin said.
“Some El Nino events which were much-less significant in how far the Pacific Ocean temperatures were above normal, like 2002 and 2006, had much more widespread dry conditions.”
HOW LONG WILL IT LAST?
THE life cycle of an El Nino typically runs from the southern hemisphere’s winter through to the following autumn, Dr Trewin said.
“The indications from climate models are that this one is likely to follow that sequence and that it will break down during the early months of next year,” he said.
“The chance it will continue into a second full year are fairly low, based on both how El Nino events behave historically and what our models are telling us about this event.”
IS THERE MARGIN FOR ERROR IN FORECASTS?
“ONCE you get to this stage of the year, the actual occurrence of a El Nino event is pretty predictable,” Dr Trewin said.
“If you have an event established in August the chances that there will be any significant breakdown before the end of the year are pretty minimal.”
He said how an El Nino translated into climate in different parts of the world was more uncertain. While some areas were “pretty consistent” the further from “that equatorial Pacific zone, the more inconsistent the impact of El Nino gets”.
ITS IMPACT ON …
EASTERN AUSTRALIA
THE most consistent El Nino signal is typically in inland NSW and inland Queensland, Dr Trewin said. “Victoria historically has been a little bit more hit and miss,” he said.
“Having said that, our outlook for August to October leans dry in most of eastern Australia, but not particularly strongly. We’ve got a 60 per cent or above chance of below-normal rainfall in southern Victoria and northeast NSW, but in the most of the rest of eastern Australia, the odds have not shifted strongly from 50:50.”
WESTERN AUSTRALIA
WESTERN Australia is not typically effected by El Nino, Dr Trewin says. “The odds (for August-October rainfall) have actually shifted quite strongly in favour of above-normal rainfall in many parts of WA,” he said.
UNITED STATES
EL NINO usually equals above-average rain for the US, particularly in the southwest and southeast. Dr Trewin said currently modelling indicated a likely later impact this year, or “most pronounced during their winter”.
SOUTH AMERICA
DURING an El Nino year, more rain on the west coast of South America is expected “during the later part of the year and early the following year”.
“We are starting to see significantly above-normal rainfall in parts of subtropical South America like northern Argentina and Uruguay, which is pretty characteristic of El Nino,” Dr Trewin said.
INDIA
THE Indian monsoon season is “starting to track somewhat below normal, which is a fairly typical El Nino signal”, Dr Trewin says.
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