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Earth's water cycle is changing much faster than expected

New research led by scientists at the University of New South Wales (UNSW) has Investigated how our water cycle is changing as a result of global warming. The water cycle is the cycling of water from rivers, streams, lakes and the ocean into clouds and back into precipitation. This cycle is extremely important in keeping Earth habitable.

Unfortunately, scientists have known for a while that climate change is impacting the water cycle and making wet places wetter, while simultaneously making dry places even drier.  

“We already knew from previous work that the global water cycle was intensifying,” said study lead author Dr. Taimoor Sohail. “We just didn’t know by how much. The movement of freshwater from warm to cold areas forms the lion’s share of water transport. Our findings paint a picture of the larger changes happening in the global water cycle.”

The changes in the water cycle are also making an impact on the ocean, changing the salinity based on the temperature of different regions. In fact, with 80 percent of Earth’s evaporation happening over ocean, it was only through tracking the changes in salt that the researchers observed water cycle changes at all.

The scientists found that somewhere between two and four times as much freshwater has moved through the cycle compared to what models anticipated. This shows that the whole system is speeding up.

“In warmer regions, evaporation removes fresh water from the ocean leaving salt behind, making the ocean saltier,” said study co-author Professor Jan Zika. “The water cycle takes that fresh water to colder regions where it falls as rain, diluting the ocean and making it less salty.”

An unanticipated amount of water has moved from the equator to the poles. Compared to what was expected, about 46,000 to 77,000 cubic kilometers more water had shifted toward the poles. All of these changes must be identified for planning and preparation for what is to come. 

“Changes to the water cycle can have a critical impact on infrastructure, agriculture, and biodiversity,” said Dr. Sohail. “It’s therefore important to understand the way the climate change is impacting the water cycle now and into the future.”

The research lays important groundwork for future studies on how Earth’s climate has evolved. “In 10 or 20 years from now, scientists can use this reference to find out how much these patterns are further changing over time.” said Dr. Sohail. 

The study is published in the journal Nature.

By Zach Fitzner, Staff Writer

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