Global warming is changing the water cycle across the planet

A report led by researchers at the Australian National University (ANU) concludes that global warming is changing the water cycle across the planetwhile warning that phenomena such as sudden droughts will be more frequent in the coming years.

In it third consecutive year of La Niña, throughout 2022 droughts intensified in the Americas and floods were recorded in parts of Asia and Oceania, according to a report by the Global Water Monitor Consortium. Lead author Professor Albert Van Dijk says the study provides a unique snapshot of global water availability today.

“It typically takes many months to collect, collate, analyze and interpret this kind of data,” Professor Van Dijk, from ANU’s Fenner School of Environment and Society, said in a statement.

“Making the most of the instruments of the satellites that orbit the Earth and by automating the entire process of data analysis and interpretation, our team has been able to reduce that time to a few days.”

The group combined water measurements from thousands of ground and satellite stations to obtain up-to-date information on precipitation, air temperature and humidity, ground water, river flows, and water volume in natural and man-made lakes.

On a global scale, in 2022 the water cycle was dominated by relatively warm oceanic waters in the western Pacific and eastern and northern Indian Oceans. As a consequence, a severe heat wave occurred in South Asia earlier in the year, followed by a very wet monsoon that caused massive flooding in Pakistan.

In other places, such as Europe and China, extreme heat waves led to so-called “flash droughts.”that is, droughts that develop a few months after severe heat waves, causing low river flows, agricultural damage and forest fires.

The report shows that the air temperature over land in 2022 followed the long-term warming trend, while air humidity is decreasing.

“This means that nature, crops and people will need more water to stay healthy, exacerbating the problem.”said Professor Van Dijk.

“It’s a sure thing that we’re going to see more and more of these heat waves and flash droughts.. We also see evidence of the impact of global warming on glaciers and the water cycle in cold regions, and indeed melting glaciers contributed to Pakistan’s flooding. That will continue until those glaciers disappear.”

The role of La Niña

A key feature of 2022 is that it was the third consecutive year of La Niña. This caused flooding problems in Australia, but also deepened drought conditions in the western United States and parts of South America.

“It is not yet known whether those three years of La Niña were a statistical fluke or the first hints of something more sinister,” said Professor Van Dijk.

“If the La Niña or El Niño patterns are going to stick around longer in the future, that’s going to cause a lot of problems, with worse and longer droughts and equally worse floods”.

The report also offers an outlook for 2023, with relatively dry conditions indicating the possibility of intensifying or new droughts in parts of North and South America, Central Asia, China and the Horn of Africa. Nevertheless, La Niña conditions are subsiding, so there is hope that water availability may return to more normal levels soon in some of those regions.

The Global Water Monitor is a joint initiative of several public and private research and development organizations that share the goal of providing free, fast, global information on climate and water resources.

Full report: https://wenfo.org/globalwater/2022report/