Scientists warn of more La Nina events in eastern Australia

 Australia's eastern states are likely to become more flood-prone in the coming decades due to increasing La Nina events, according to a new study.

The report, published in the Nature Climate Change journal on Tuesday, said the destructive weather pattern could become more prevalent because climate change has slowed down the "conveyor belt" of currents in the Atlantic Ocean.

The oceanic feature, known as the Atlantic meridional overturning circulation, involves the regular movement of a massive flow of warm tropical water which, in turn, has a major influence on weather across the planet.

The report's authors from the University of New South Wales (UNSW) said the Atlantic overturning had been relatively stable for about 5,000 years but had slowed down in recent decades.

A contributing factor has been the release of greenhouse gases which have triggered the melting of trillions of tons of polar ice caps in Greenland and Antarctica, which has led to massive amounts of freshwater entering the ocean system, altering its buoyancy characteristics and upturning marine ecosystems.

Australians in the eastern states including Queensland, New South Wales (NSW) and Victoria have become familiar with the impact of prolonged La Nina events during the past year.

Unprecedented flooding occured across those states with the weather phenomenon only now "slowly weakening," according to an Australian Bureau of Meteorology (BoM) report released on Tuesday.

Explaining their findings in the online journal the Conversation on Tuesday, the research team of UNSW Scientia Professor Matthew England, Associate Professor Andrea S. Taschetto and PhD candidate Bryam Orihuela-Pinto wrote that "the oceans are the flywheel of Earth's climate, slowing the pace of change by absorbing heat and carbon in vast quantities".

"But there is payback with sea level rise, ice melt, and a significant slowdown of the Atlantic overturning circulation projected for this century."

The researchers said the "current trajectory of unabated greenhouse gas emissions is giving the whole system a giant kick" which could ultimately lead to the collapse of the ocean's "conveyor belt."

To avert or at least ameliorate such an environmental disaster would require the rapid development of a new low-carbon economy, they said.

"Doing so will change, for the second time in less than a century, the course of Earth's climate history -- this time for the better."