A marine heatwave off Western Australia that killed fish and bleached coral was driven by unusual features in a warm ocean current, new research shows. During the 2011 heatwave, water temperatures were more than three degrees Celsius above long-term seasonal averages.
At the peak of the event, for a two-week period, water temperatures climbed up to five degrees Celsius above long-term seasonal averages.CSIRO's Dr Ming Feng said the heatwave was driven by unusual features in the Leeuwin Current, a warm ocean current that flows southwards near Australia's west coast.
"Record easterly wind in the eastern Pacific and record northerly wind in the southeast Indian Ocean combined to produce an unseasonable surge of the southward-flowing Leeuwin Current," Dr Feng said.
The unusual conditions were caused by the La Nina climate phenomenon, which brings rain, floods and cyclones, while its counter-cycle El Nino causes drought.
Understanding the factors behind the heatwave was a step towards preparing for the impacts of extreme warming events in the future, Dr Feng said.
Source: WA Today
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