Climate Change

Drought risk to soar even at 1.5C


The risk of extreme El Nino events that suck rain away from Australia and cause drought will keep climbing even if the climate stabilises, scientists warn.

Extreme El Nino events that can cause crippling drought in Australia are likely to be far more frequent even if the world pulls off mission improbable and limits global warming to 1.5 degrees.

International scientists have just released new modelling that projects drought-causing El Nino events, which pull rainfall away from Australia, will continue rising well beyond any stabilisation of the climate.

Even if warming is limited to the world's aspirational target of 1.5 degrees - something scientists have warned is unlikely if not impossible - the modelling suggests Australia will face more frequent drought-inducing weather events.

The risk of extreme El Nino events will rise from the current five events per century, to 10 per century by 2050 under a scenario that presumed warming peaks at 1.5 degrees then.

But the risk keeps on rising for a further 100 years - to about 14 events per century by 2150.

In short, the risk of extreme El Nino events won't stabilise even if the climate is stabilised, CSIRO researcher and lead author Dr Guojian Wang says.

"This result is unexpected and shows that future generations will experience greater climate risks associated with extreme El Nino events than seen at 1.5C warming," Dr Wang says.

Report co-author Dr Wenju Cai says extreme El Nino events occur when the usual El Nino Pacific rainfall centre is pushed eastward, toward South America. Sometimes it moves by up to 16,000km, causing massive changes in the climate.

"This pulls rainfall away from Australia bringing conditions that have commonly resulted in intense droughts across the nation," says Dr Cai, director of the Centre for Southern Hemisphere Oceans Research.

"During such events, other countries like India, Ecuador, and China have experienced extreme events with serious socio-economic consequences."

The global Paris climate change agreement seeks to limit global warming to below 2 degrees, a target intended to avoid the worst impacts of climate change.

But the Paris deal, recently abandoned by the United States, also set an aspirational target of 1.5 degrees - a demand from the most vulnerable countries, including low-lying island nations in the Pacific that may not survive at 2 degrees.

Dr Scott Power heads climate research at the Bureau of Meteorology and says most small island states in the Pacific have a limited capacity to cope with major floods and droughts, and the latest modelling is very bad news for them.

"To make matters worse, our recent study published ... indicates that the risk of major disruptions to Pacific rainfall have already increased. And, unfortunately, these El Nino-related impacts will add to the other challenges of climate change, such as rising sea levels, ocean acidification and increasing temperature extremes."

The latest research on the El Nino risk has been published in the journal Nature Climate Change.

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