Since 2002, Earth’s continents have been undergoing a dramatic and unprecedented transformation marked by substantial freshwater loss, a phenomenon driven by a complex interplay of climate change, unsustainable groundwater extraction, and worsening drought conditions. This alarming trend was revealed through over two decades of satellite observations, spearheaded by a research team led by Arizona State University and published in Science Advances. Their study identifies four expansive “mega-drying” regions exclusively located in the northern hemisphere, highlighting a looming crisis with far-reaching consequences for water security, agriculture, sea level rise, and global socioeconomic stability.
The empirical evidence collected from the US-German GRACE and GRACE-Follow On (GRACE-FO) satellite missions, which monitor terrestrial water storage, confirms a stunning acceleration in drying patterns that now outpace wetting trends worldwide. Terrestrial water storage encompasses all forms of surface water, including soil moisture, snow, ice, vegetation, and critically, groundwater. The data indicates that the expansion of drying zones is occurring at an alarming rate—roughly twice the size of California’s landmass each year—signaling a rapid transformation of the planet’s hydrological balance.
Groundwater depletion emerges as a particularly grave component of this crisis, accounting for approximately 68% of the total freshwater losses on land over the past two decades. This startling proportion reveals that underground aquifers, which are often considered reliable reserves or “ancient trust funds” of freshwater, are being overexploited unsustainably. These groundwater reserves contribute more extensively to sea level rise than the melting of glaciers and ice caps, making the crisis not only a terrestrial issue but one with significant implications for the world’s oceans.
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The researchers underscore the gravity of these shifts by noting that 75% of the global population inhabits regions experiencing continuous freshwater losses, affecting 101 countries around the world. With the United Nations projecting further population growth over the coming half-century, this imbalance threatens to exacerbate water scarcity at a planetary scale. The combination of increasing demand and decreasing supply introduces complex challenges for ensuring equitable water distribution and sustaining agricultural production.
A critical turning point in this hydrological narrative appears to have occurred around 2014–2015, coinciding with significant climatic events such as the “mega El Niño.” This period marked an intensification of continental drying, a surge in groundwater extraction, and a decline in the buffering effect of glacial and ice sheet meltwater. Additionally, satellite data reveal shifts in hemispheric water patterns post-2014, with drying predominantly migrating to northern hemisphere landmasses, while wet regions oscillated primarily to the southern hemisphere—a dynamic previously undocumented.
The mega-drying regions identified in this latest research encompass vast and diverse geographic expanses. In North America, the southwestern United States and Central America are suffering extreme water deficits amid some of the country’s most important agricultural zones and rapidly expanding desert cities like Phoenix, Las Vegas, and Mexico City. Similarly, Alaska and Northern Canada face accelerating glacier recession, permafrost thaw, and diminishing soil moisture in key farming territories such as British Columbia and Saskatchewan. Northern Russia endures snowpack and permafrost melt at a scale disrupting ecosystems and water availability, while the Middle East-North Africa (MENA) to Pan-Eurasia region confronts acute freshwater challenges with major urban centers, deserts, and shrinking inland seas like the Caspian and Aral experiencing profound drying.
Remarkably, while most latitudinal bands around the globe are trending towards greater dryness, tropical regions stand out as an exception, continuing to get wetter on average—a development that diverges from many projections by the Intergovernmental Panel on Climate Change (IPCC). These anomalies highlight the critical need for continuous, long-term hydrological monitoring, as evolving patterns challenge existing climate models and water management paradigms.
The implications of sustained continental drying are profound and multifaceted. Agricultural productivity threatens to falter under water shortages, risking global food security for billions. Biodiversity, intimately linked to both aquatic and terrestrial water availability, faces unprecedented stress. We also see the acceleration of sea level rise driven not just by melting ice but by the transfer of terrestrial water into the oceans, compounding threats to coastal infrastructure and ecosystems. These interconnected vulnerabilities emphasize that freshwater depletion is a planetary-scale issue necessitating urgent, coordinated responses.
Experts involved in the study stress the importance of recognizing the unrecoverable nature of many water losses. Groundwater aquifers and glacial reserves do not replenish on human timescales, implying a potential freshwater “bankruptcy” if current practices continue. Utilizing non-renewable water sources as though they were inexhaustible is a critical mistake that demands immediate attention in water policies worldwide. Furthermore, the failure to actively replenish aquifers during wet periods is worsening the imbalance.
Mitigating this crisis requires integrated efforts spanning scientific research, policy innovation, and international collaboration. The study’s authors advocate for new global groundwater management frameworks and sustainable usage policies that prioritize long-term water security. They also call for enhanced data sharing and the expansion of both satellite and in situ hydrological observations to refine models, monitor trends, and support adaptive water management strategies.
As the global community grapples with the realities of climate change, this research serves as a planetary wake-up call. While climate mitigation efforts continue to face challenges, adjusting water governance to address continental drying can provide an immediate and impactful lever to protect freshwater resources. Strategic water management aimed at conserving groundwater and safeguarding terrestrial water storage will slow sea level rise impacts and provide vital resilience for future generations.
In addition to informing policymakers, this body of work supports ongoing and future assessments by organizations such as the World Bank, which plans to incorporate these findings into flagship reports focused on the human and economic dimensions of freshwater depletion. By coupling technical insights with actionable recommendations, this research lays the groundwork for targeted interventions that can ameliorate water scarcity and promote sustainable development across drying continental regions.
The unprecedented loss of freshwater on Earth’s continents illuminated by this study underscores a crisis that is as urgent as it is complex. Addressing it will require an all-hands-on-deck approach, leveraging the best scientific tools and the strongest policy frameworks to secure water for people and ecosystems alike amid a transforming climate.
Subject of Research: Not applicable
Article Title: Unprecedented Continental Drying, Shrinking Freshwater Availability, and Increasing Land Contributions to Sea Level Rise
News Publication Date: 25-Jul-2025
Web References: https://www.science.org/doi/10.1126/sciadv.adx0298
References: Data from US-German GRACE and GRACE-Follow On satellite missions, and related studies on terrestrial water storage.
Image Credits: Image by Sophia Franz
Keywords: Climatology, Hydrogeology, Groundwater, Water resources, Watersheds, Oceans, Earth systems science
Tags: climate change impact on waterdrought conditions and agriculturefreshwater resources declineglobal water crisisgroundwater depletionhydrological balance transformationmega-drying regionssatellite observations of water losssocioeconomic effects of water scarcityterrestrial water storage monitoringunsustainable water extraction practiceswater security challenges