Indian Ocean system that drives extreme weather in Australia likely to worsen with global heating

Reported today on The Guardian

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Indian Ocean system that drives extreme weather in Australia likely to worsen with global heating

Researchers believe the Indian Ocean Dipole is more clearly influenced by climate change than previously thought

Indian Ocean surface temperatures that helped drive hot and dry conditions in eastern Australia last year were more clearly influenced by climate change than previously thought and are likely to worsen in future, researchers have found.

Scientists studying a phenomenon known as the Indian Ocean Dipole say their observations suggest Australia could experience future conditions even more extreme than those that elevated the bushfire risk during the 2019-20 fire season.

The work, led by the Australian National University and the ARC Centre of Excellence for Climate Extremes, used coral records from the eastern equatorial Indian Ocean to examine the occurrence of "extreme positive" Indian Ocean Dipole events over the past millennium.

The Indian Ocean Dipole (IOD) is the difference in temperature between the western and eastern Indian Ocean. When the IOD is in positive mode, warmer waters develop off the Horn of Africa and cooler waters develop off Indonesia. This leads to hotter and drier weather in Australia.

An "extreme positive" event is when these conditions are particularly severe. Last year, an extreme positive IOD played a role in bushfires in Australia and floods in Africa.

The scientists used fossil and modern coral cores to examine how frequently these events occurred back to 1240. Analysing data from 500 of those years, they found an extreme positive Indian Ocean Dipole like the one Australia experienced in 2019 was rare, occurring just 10 times.

Lead author Nerilie Abram, a climate scientist at the Australian

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