NASA study exposes increasing human effects on the global water cycle
Climate change and human activities are reshaping the global water cycle, impacting ecosystems and water management worldwide.
![Climate change and human activities are causing significant disruptions to Earth's natural systems, including the global water cycle.](https://www.thebrighterside.news/uploads/2025/01/water-1.webp?auto=webp&auto=webp&optimize=high&quality=70&width=1440)
Climate change and human activities are causing significant disruptions to Earth’s natural systems, including the global water cycle. (CREDIT: NPS/Kurt Moses)
Climate change and human activities are causing significant disruptions to Earth's natural systems, including the global water cycle. These disruptions have introduced variability and irregularities that challenge assumptions about the stability of geophysical processes.
As a result, water resource management strategies and risk assessments based on outdated assumptions are increasingly unreliable. Understanding these shifts is critical for managing water resources and mitigating the risks associated with hydrological extremes, such as droughts and floods.
Shifting Patterns in the Global Water Cycle
For years, water resource management relied on the assumption that precipitation, temperature, and other geophysical variables would remain statistically stable over time. However, recent studies reveal that these assumptions no longer hold true in many regions.
Changes in precipitation patterns and the increasing intensity of extreme weather events have highlighted the nonstationary nature of hydrological processes. This nonstationarity, influenced by both climate change and human activities, complicates the task of predicting and managing water availability.
Unlike temperature and precipitation changes, which are primarily driven by global warming, terrestrial hydrological processes are directly impacted by human activities. Urbanization, deforestation, agriculture, and river damming have all played a role in altering the water cycle.
These activities, combined with climate change, amplify the variability in terrestrial water storage (TWS) and introduce uncertainties in hydrological modeling.
Despite the progress in monitoring TWS trends, the full extent of nonstationarity remains poorly understood. Current research has largely focused on long-term trends, neglecting other critical factors such as seasonal variability and the frequency of extreme events. These overlooked elements are essential for comprehensively quantifying changes in the water cycle.
New Insights from NASA Research
Recent work by NASA scientists provides groundbreaking insights into these changes. Using nearly two decades of satellite data, researchers have shown that human interventions in the water cycle are more significant than previously thought.
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This research, published in the Proceedings of the National Academy of Sciences, highlights how activities like agriculture and groundwater extraction drive unprecedented shifts in the global water cycle.
Sujay Kumar, a research scientist at NASA’s Goddard Space Flight Center and a co-author of the study, emphasized the profound impact of human activities. “We established with data assimilation that human intervention in the global water cycle is more significant than we thought,” Kumar said.
The study also underscores the limitations of traditional water management practices. According to Wanshu Nie, the study’s lead author, these practices often assume a predictable range of water cycle variability. “This may no longer hold true for some regions,” Nie said.
The research aims to guide improvements in assessing water resource variability and planning for sustainable management, particularly in areas most affected by these changes.
Measuring Nonstationarity with Advanced Tools
To quantify nonstationarity in the water cycle, NASA researchers developed a novel nonstationarity index (NSI). This index is based on three key metrics: the long-term trend of water storage changes, shifts in seasonal cycles, and the frequency of extreme events.
By analyzing satellite data from 2003 to 2020, the researchers produced a global assessment of these changes at a high spatial resolution.
The study relied on multiple satellite datasets, including precipitation data from the Global Precipitation Measurement mission, soil moisture data from the European Space Agency’s Climate Change Initiative, and terrestrial water storage data from the Gravity Recovery and Climate Experiment (GRACE) satellites.
Additional vegetation health information was obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite instrument.
“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 NASA research scientist and co-author of the paper.
Implications for Water Resource Management
The findings reveal three major types of shifts in the water cycle: long-term trends, seasonal changes, and altered frequency of extreme events. For instance, some regions experience a decline in groundwater levels, while others see earlier snowmelt or extended growing seasons. Extreme events, such as 100-year floods, are also occurring more frequently.
One notable example is North China, where ongoing drought conditions coexist with thriving vegetation due to extensive irrigation. Farmers in the region pump groundwater to compensate for the lack of precipitation, but this practice depletes water reserves and affects other aspects of the water cycle, such as evapotranspiration and runoff. These interrelated effects highlight the complexity of human-induced changes in the water cycle.
Nie and her colleagues emphasize that these shifts have far-reaching implications for water management. Infrastructure designed for flood control or drought mitigation often relies on outdated assumptions about water cycle stability. To adapt to the “new normal,” resource managers must integrate the ongoing effects of human activities and climate change into their planning.
“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,” Nie said.
The study’s results also suggest that Earth system models used to simulate the global water cycle should evolve. By incorporating the effects of human activities and leveraging improved satellite data, these models could provide more accurate predictions and help communities prepare for future water challenges.
Bridging Science and Policy
The research underscores the urgent need for collaboration between scientists, policymakers, and resource managers. Advanced tools like the NSI can provide valuable insights into the complex interplay between climate change and human activities. However, translating these findings into actionable policies requires a concerted effort.
For regions already experiencing significant shifts in the water cycle, proactive measures are essential. These include updating infrastructure, improving water use efficiency, and developing early warning systems for droughts and floods. By addressing these challenges head-on, societies can build resilience against the growing uncertainties of a changing water cycle.
In conclusion, the global water cycle is undergoing profound changes driven by both climate change and human activities. These shifts challenge traditional assumptions and demand innovative approaches to water management.
By leveraging cutting-edge research and technology, humanity can better understand and adapt to the evolving dynamics of the planet’s most vital resource.
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