The Bureau of Meteorology has raised its prediction of an El Niño weather pattern striking Australia this summer to 70 per cent, up from 50 per cent just two weeks ago. El Niño, a climatic event occurring roughly every five years, is defined by substantial warming of Pacific Ocean sea surface temperatures.
In Australia, El Niño is characterised by droughts and abnormal heat, particularly in the eastern and southern coasts, which are already experiencing a dry spell. The event is largely triggered by changes in the Pacific Ocean, where sub-surface temperatures in the central to eastern areas are already 4 degrees warmer than average.
'We're seeing very warm temperatures in the tropical Pacific Ocean, about 1 degree above average,' said Andrew Watkins, the bureau's manager of climate prediction service. 'Things seem to have evolved fairly quickly in the last few weeks.' He noted that the central tropical Pacific has reached temperatures at El Niño levels now.
The bureau uses five international models from France, England, America, Canada and Japan, plus its own model called Poama, to reach its conclusions. In its latest fortnightly El Niño Southern Oscillation (ENSO) Wrap-Up, the BoM has lifted its ENSO tracking status from 'watch' to 'alert'.
Mr Watkins warned that while it can be difficult to classify the event conclusively, there are telltale signs that El Niño will be reached by December. Warmer Pacific temperatures combined with cooler seas around northern Australia may mean fewer tropical cyclones but also fewer rain depressions relied upon by drought-affected farmers in Queensland.
According to US weather agencies, 2014 has been the warmest April-September period on record, posing a serious threat that it could be the hottest year overall. The current warmest year is a tie between 2005 and 2010.
