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The global water cycle is changing and that spells bad news



As La Niña caused flooding rains in Australia it intensified droughts in the Americas, a first-of-its-kind report helmed by Australian scientists has found.

The report, released today by the Global Water Monitor Consortium and led by The Australian National University (ANU), found global warming is changing the water cycle across the planet.

In 2022 the water cycle was dominated by warm ocean waters in the western Pacific, eastern and northern Indian Ocean as air temperature over land followed the long-term warming trend, and air humidity declined.

This in turn fuelled extreme natural disasters across the globe.

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Standardised anomaly in annual average air temperature.

Warm ocean temperatures led to the formation of a severe heatwave in South Asia early in the year, followed by an extreme monsoon that caused massive floods in Pakistan.

The year also coincided with the rise of "flash droughts" – dry spells which rapidly develop within a few months following severe heatwaves – across Europe and China.

Lead author Professor Albert van Dijk warned events like flash droughts and extreme floods, will become more frequent as the water cycle shifts.

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"If La Niña or El Niño patterns are going to stay around longer in future, that is going to cause a lot of trouble, with worse, longer droughts and worse floods alike," he said.

"It's a safe prediction that we will see more and more of these heatwaves and flash droughts.

"We also see evidence of the impact of global warming on glaciers and the water cycle in cold regions, and in fact melting glaciers contributed to the Pakistan floods.

"That will continue until those glaciers are gone."

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One can't talk about 2022 without making reference to the fact it was the third La Niña year in a row.

While three consecutive years are unusual it isn't entirely unprecedented, but as the water cycle shifts it remains unclear whether back-to-back events are now the norm.

"The jury is still out on whether those three La Niña years were a statistical fluke or the first signs of something more sinister," Van Dijk said.

To collate their findings researchers combined water measurements from thousands of ground stations and by satellites, producing up-to-date information on rainfall, air temperature and humidity, soil water, river flows and the volume of water in natural and artificial lakes.

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