Cracked mud and salt on the valley floor in Death Valley National Park in California can transform into a mirror-like surface after rainfall (image credit: NPS/Kurt Moses).
Research Uncovers Unseen Changes in the Global Water Cycle
A groundbreaking study conducted by a team at NASA has revealed that significant alterations are occurring within the global water cycle, shifts previously overlooked. The majority of these transformations appear to stem from human activities, particularly agricultural practices, which may impact ecosystems and water management strategies globally.
Innovative Use of Technology for Water Cycle Observations
The research is based on nearly two decades’ worth of satellite observations and remote measurement technologies. According to Sujay Kumar, a research scientist at NASA’s Goddard Space Flight Center in Maryland and co-author of this pivotal study, “We have demonstrated through data assimilation that human influence on the global water cycle is greater than we had anticipated.”
Global Repercussions of Water Cycle Changes
The effects described in this study could concern individuals worldwide. Traditional approaches to water management—such as infrastructure design for flood mitigation or creating drought early warning systems—are often anchored in the belief that water cycle variations remain confined within specific limits. Wanshu Nie, lead author and research scientist at NASA Goddard, emphasized that “This assumption may no longer be valid for certain areas.” She expressed hopes that this investigation will aid more accurate assessments of variability in water resources while guiding sustainable management strategies where these changes are most pronounced.
Regional Case Study: North China’s Drought Challenge
Northern China serves as a poignant example where new human-related impacts on the hydrological cycle are evident. The region currently suffers from an extensive drought; however, lush vegetation persists largely due to farmers irrigating their fields by extracting additional groundwater supplies. Kumar pointed out how these intertwined human interventions produce complex effects influencing other aspects of the water cycle such as evapotranspiration rates and runoff patterns.
Identifying Key Shifts Within Water Patterns
The study categorized three types of changes impacting the hydrological system:
- a long-term trend like declining levels within groundwater reserves;
- a shift in seasonal patterns including earlier starts to growing seasons or premature snowmelt;
- a rise in frequency concerning extreme weather events such as what were once termed “once-in-a-century floods.”
A Comprehensive Analytical Approach Using Satellite Data
Citing data accrued from 2003 to 2020 across various NASA satellites—which include precipitation measurements via the Global Precipitation Measurement mission satellite; soil moisture information from Europe’s Climate Change Initiative; plus terrestrial storage evaluation through Gravity Recovery and Climate Experiment satellites—the researchers also incorporated vegetation health assessments provided by instruments aboard Moderate Resolution Imaging Spectroradiometer satellites. Augusto Getirana, another co-author from NASA Goddard remarked about their team’s continuous efforts optimizing satellite data analysis capabilities: “This paper encapsulates years spent enhancing our ability to accurately model continental-scale water fluxes and storage.”
Evolving Earth System Models for Future Predictions
The findings indicated that existing Earth system models must transform—including integration with ongoing anthropogenic influences—to effectively simulate future scenarios about global hydrological conditions. Enhanced modeling techniques coupled with better access to data will enable producers along with resource managers comprehend local conditions deemed part of a “new normal,” according to Nie.
A Significant Publication Announcement
This essential paper titled “Nonstationarity in the global terrestrial water cycle and its interlinkages in the Anthropocene” was published on October 28th, 2024 in Proceedings of the National Academy of Sciences.