Ag Weather Forum

On the cusp of the 2025 U.S. crop season -- and even as heavy flooding rain looms over the northern Delta and the southeastern Midwest -- new research by hydrologists from Australia, South Korea and the United States find that Earth is getting drier. In fact, the Earth may have lost so much soil moisture that it cannot be fully recovered due to climate change.

The research project was recently summarized in the journal Science. Lead scientists were University of Melbourne (Australia) Hydrology Professor Dongryeol Ryu and Ki-Weon Seo, a hydrology professor at the Seoul National University (South Korea). Research results have been summarized by a number of news and information providers including the Associated Press, Australia Broadcasting Corporation, Carbon Brief and Inside Climate News.

The research finds that the Earth lost more than 2,614 gigatons of moisture between 2000 and 2016. That loss of soil moisture is so large that it surpasses the melting of Greenland's ice sheet in contributing to sea level rise. The research also found that soil moisture loss is affecting the wobble in the Earth's rotation.

The scientists estimate that this loss of soil moisture has gone on since the early 1990s. But, since 2000, the drying out has been dramatic. The researchers estimated that between 2000 and 2002 alone, world soil moisture loss totaled about 1,614 gigatons. That compares to a 900 gigaton loss of ice in Greenland from 2002 to 2006. An additional 1,009 gigatons of soil moisture were lost from 2003 to 2016. The research project found that this soil moisture loss was likely the main contributor to a notable sea level rise of almost 2 millimeters (about .08 inches) annually between 2000 and 2002.

The research combined data from satellites, sea level measurements and observations of "polar motion" (the motion in Earth's rotation axis) to analyze the decrease in world soil moisture levels since year 2000.

Study findings indicate that this drop in world soil moisture is primarily driven by an increasingly thirsty atmosphere as global temperatures rise, as well as shifts in rainfall patterns, according to a study summary published in the journal Science.

Soil moisture loss is not equal around the world; however, some big global crop areas do show consistent drying. In the U.S., the Great Plains, Southwest, and the Southeast coast fall into that category. Internationally, much of central Brazil through central Argentina is included. And China's former Manchuria region shows this drying trend as well.

The soil moisture loss study's time parameter ended with 2021, but world drying has continued. A 2024 United Nations drought report found that in the last three decades, over three-fourths of all the world's land became drier than in the previous 30 years. Temperatures keep rising -- and so do world water challenges.

More details are available here: https://www.abc.net.au/…

Bryce Anderson can be reached at bryce.anderson@dtn.com

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