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How 'warm blob' east of Australia is causing Chile's megadrought

A large blob of warm water the size of Australia located in the southern Pacific has caused a "chain of events" resulting in Chile's decade-long megadrought, scientists say.

According to the study published in the Journal of Climate, the heat from the Southern Blob, which is located east of Australia and New Zealand, warms the air directly above it which winds then carry towards the South American country.

"The warm surface water that makes up the Blob then heats the air above it and as the atmosphere warms, it expands into a 'big, broad area of high pressure', known as a high-pressure ridge, Kyle Clem, one of the authors and a lecturer in climate science at Victoria University of Wellington, said.

This impacts pressure trends, affecting rainfall and resulting in dry conditions in Chile.

An aerial view of a dried area of the Penuelas Lake, in Valparaiso, Chile, on January 22, 2020.
Chile has been hit by a "megadrought" caused by a blob of warm water thousands of kilometres away. Source: AFP via Getty Images

“This big ridge of high pressure blocks storm systems that bring rainfall to central Chile in winter,” Mr Clem said.

“When we took the blob out of our simulations that ridge of high pressure disappears.

“That was one our biggest pieces of evidence that the blob is a major contributor [to the drought].”

The hot and dry conditions in Chile has resulted in snow caps melting on the Andes, reservoirs running low and once-lush landscapes withered.

Chilean authorities this year were forced to truck water to some 400,000 people living in rural areas.

In the study, scientists used computer simulations to investigate whether there was a link between the blob and years of low winter rainfall in Chile.

The blob "is only perhaps 3% of the South Pacific, but it's located in such a sensitive area that it produces this chain of events", study co-author Rene Dario Garreaud, a climate scientist at the University of Chile in Santiago, said.

A sign sits in the middle of a barren field in Chile.
The blob sits east of New Zealand and research has shown it is fuelling the drought in Chile. Source: AFP via Getty Images

While drought is not uncommon in Chile, the current megadrought has persisted since 2010.

Some scientists and politicians have begun warning of possible long-term water shortages in the central region, home to vineyards and farms.

Ocean blobs also regularly occur, dissipating within a couple of years, but the Southern Blob's prolonged and pronounced rate of warming is beyond what might occur naturally, the researchers found.

"We know that the blob is natural, but it is invigorated by climate change," Garreaud said, adding climate change was the reason it had lasted so long and the reason why it was so intense.

'Southern Blob' study has scientists concerned

More research is needed to determine how much of a role climate change has played in the phenomenon of the blob, though it is still concerning scientists who were not involved in the work.

"I find it very concerning to see that human-caused climate change is amplifying the severity of megadroughts," Andreas Prein, a climate scientist at the US-based National Center for Atmospheric Research, said.

"Such (extreme) droughts are responsible for the collapse of historic civilisations such as the Mayas or the Ming Dynasty, and can destabilise modern cultures such as recently seen in Syria."

A Climate scientist from the University of Colorado, Dillon Amaya, said the fact the blob was impacting Chile thousands of kilometres away shows how broadly climate change will impact our planet.

"We need to be cognisant of the changes that are happening in global climate thousands of miles away," Amaya said.

"It's all connected."

With Reuters

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