Ocean research unlocking mysteries of Australia’s wild weather

A new batch of research may provide the best explanation yet for the wild variations in Australia's weather.

University of Technology Sydney researchers have found that conditions in three oceans that surround Australia combined to amplify each other's influence and explain Australia's 21st century weather.

Co-author of the paper published in Nature's Scientific Reports, James Cleverly said although meteorologists have linked dry years with the Pacific Ocean's El Nino phase (ENSO), this explanation did not fully account for variations.

“If you look at the correlation between El Nino and rainfall in central Australia, it kind of comes and goes – sometimes it's related and sometimes it isn't, so there appeared to be more problems with that answer than solutions,” Cleverly said.

The research paper stated ENSO–precipitation correlations were present in only 31% of the last 100 years, and often absent in wet years.

“In this study, we demonstrate that the abnormally large fluctuations in precipitation experienced by Australia are not a result of any single climate mode, but instead are due to periods of synchronisation amongst three climate modes: ENSO (equatorial Pacific Ocean), IOD (equatorial Indian Ocean) and SAM (Southern Ocean),” Cleverly and co-author Derek Eamus wrote.

“This entirely novel finding has been speculated upon, but the method required to test this hypothesis has not been presented before now.”

The research used an advanced temporal scaling method to identify interactions between the climate modes.

“When these climate modes synchronised (1999–2012), drought and extreme precipitation were observed across Australia,” the paper states.

Cleverly, who completed his PhD in leaf-level physiology of riparian vegetation at the University of Nevada, started looking into climate modes when he arrived in Australia to visit the red centre in 2010.

“It was greener and wetter than all of my previous experiences of living in the deserts of south-western North America … but then in late 2011, all the way through to 2013, it was pretty much drought-stricken again,” he said.

“I wanted to explain some of the large amounts of variability we see in productivity in the greening of the vegetation and so that's why I looked at the climate modes because there really wasn't a good explanation yet for why we get these extreme fluctuations between wet and dry.”

Cleverly said the findings were of international importance due to Australia's impact on the global carbon sink.

“In 2010 and 2011, there was a 20% increase in net primary photosynthetic productivity globally and that was attributed to the additional greening due to extreme precipitation throughout the southern hemisphere. 56% of it was attributed to Australia alone,” Cleverly said.

For more information, visit the full report here