NASA Reveals Shocking Human Impact on Earth’s Water Cycle

NASA scientists have uncovered significant changes in the global water cycle over the past two decades, largely driven by human activities such as agriculture.

Their findings reveal that common water management assumptions may no longer hold true in certain regions, which could have profound consequences for drought planning and flood management.

Global Water Cycle Undergoing Major Shifts

NASA scientists have analyzed nearly 20 years of data and found that the global water cycle is changing in ways never seen before. These changes, largely driven by human activities such as agriculture, could significantly affect ecosystems and how water resources are managed, particularly in certain regions.

“We established with data assimilation that human intervention in the global water cycle is more significant than we thought,” said Sujay Kumar, a research scientist at NASA’s Goddard Space Flight Center in Maryland and co-author of the study, which was published in the Proceedings of the National Academy of Sciences.

Impacts on Water Management Strategies

These changes have worldwide implications. Many current water management strategies — such as building flood-resistant infrastructure or developing drought warning systems — are based on the assumption that the water cycle remains within predictable limits, explained Wanshu Nie, lead author of the study and a research scientist at NASA Goddard.

“This may no longer hold true for some regions,” Nie noted. “We hope that this research will serve as a guide map for improving how we assess water resources variability and plan for sustainable resource management, especially in areas where these changes are most significant.”

One example of the human impacts on the water cycle is in North China, which is experiencing an ongoing drought. But vegetation in many areas continues to thrive, partially because producers continue to irrigate their land by pumping more water from groundwater storage, Kumar said. Such interrelated human interventions often lead to complex effects on other water cycle variables, such as evapotranspiration and runoff.

Three Key Types of Water Cycle Changes

Nie and her colleagues focused on three different kinds of shifts or changes in the cycle: first, a trend, such as a decrease in water in a groundwater reservoir; second, a shift in seasonality, like the typical growing season starting earlier in the year, or an earlier snowmelt; and third a change in extreme events, like “100-year floods” happening more frequently.

The scientists gathered remote sensing data from 2003 to 2020 from several different NASA satellite sources: the Global Precipitation Measurement mission satellite for precipitation data, a soil moisture dataset from the European Space Agency’s Climate Change Initiative, and the Gravity Recovery and Climate Experiment satellites for terrestrial water storage data. They also used products from the Moderate Resolution Imaging Spectroradiometer satellite instrument to provide information on vegetation health.

Advancing Water Cycle Models for the Future

“This paper combines several years of our team’s effort in developing capabilities on satellite data analysis, allowing us to precisely simulate continental water fluxes and storages across the planet,” said Augusto Getirana, a research scientist at NASA Goddard and a co-author of the paper.

The study results suggest that Earth system models used to simulate the future global water cycle should evolve to integrate the ongoing effects of human activities. With more data and improved models, producers and water resource managers could understand and effectively plan for what the “new normal” of their local water situation looks like, Nie said.

Reference: “Nonstationarity in the global terrestrial water cycle and its interlinkages in the Anthropocene” by Wanshu Nie, Sujay V. Kumar, Augusto Getirana, Long Zhao, Melissa L. Wrzesien, Goutam Konapala, Shahryar Khalique Ahmad, Kim A. Locke, Thomas R. Holmes, Bryant D. Loomis and Matthew Rodell, 28 October 2024, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2403707121

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