The decreasing water levels in soil, lakes, and rivers are posing a serious threat to agriculture.

During a train ride to visit Professor Dongryeol Ryu’s family, he and his colleague Ki-Weon Seo made a surprising discovery. While the train was temporarily halted due to technical issues, Seo was working on his computer and stumbled upon data that indicated a significant depletion of Earth’s water stored on land, which caught Ryu off guard.

“At first we thought, ‘That’s an error in the model,’” Ryu said.

After a year of checking, they determined it wasn’t.

Ryu and Seo’s recent publication in the journal Science reveals that the impact of global warming has led to a noticeable decrease in the amount of water stored in various locations such as soil, lakes, rivers, and snow worldwide. This shift, they warn, could have irreversible consequences on agriculture and sea levels. The researchers are particularly concerned about the transfer of water from land to the ocean, as it poses a significant threat to farming. They aim for their study to support initiatives aimed at reducing water consumption.

According to the study, Earth has experienced a reduction of over 2,000 gigatons of soil moisture in the past two decades. To put this into perspective, this amount surpasses the ice loss in Greenland between 2002 and 2006. Additionally, there has been an increase in the occurrence of agricultural and ecological droughts that typically happen once a decade, a rise in global sea levels, and a shift in the Earth’s pole position.

Ryu and his colleagues used three different data sources to verify that Earth storing less water on land than it once did. He also said their results reveal a deeper truth about the land, one farmers have to contend with frequently: When a big, dramatic rainfall event comes after a drought, sometimes leading to huge floods, that doesn’t mean the water stored underground has recovered.

“It seems that lands lost their elasticity to recover the previous level,” he said.

Whether that elasticity ever returns will depend on whether humans take action on climate change and significantly change water use, the researchers say. The increasing heat stress on plants means they need more water. Agriculture, particularly irrigated agriculture, continues to draw up more water than it can afford. And humans are continuing to emit greenhouse gases without a strong effort to reverse course.

“There are long-term climate changes that have happened in the past and presumably could occur in the future that could reverse the trend described, but probably not in our lifetimes,” said Katharine Jacobs, a University of Arizona professor of environmental science who wasn’t involved in the study. “Because greenhouse gases will continue to cause global warming well into the future, the rate of evaporation and transpiration is not likely to reduce any time soon.”

The study also confirms an explanation for a slight wobble in the rotation of the Earth — it’s being driven by the changing moisture levels of the planet.

“When I read this thing, I was very excited,” said Luis Samaniego, a professor of hydrology and data science at the University of Potsdam who wrote an overview commentary discussing the findings in Science. “It’s a fascinating puzzle of all disciplines that came at the right moment to verify something that was not possible before.”

But Samaniego stressed that the finding isn’t only fascinating; it’s a wake-up call. Imagine the planet’s wobble like an electrocardiogram for the Earth, he said. Seeing this result is like detecting an arrhythmia.

Choosing not to listen to the doctor — “that’s what we are playing around with at the moment,” he said.

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