Alberta West News: New Climate Change call: Continental Drying

Continental Drying: A Global Climate Crisis Reshaping Earth's Water Systems

The world is experiencing an unprecedented phenomenon known as "continental drying"—a persistent, long-term decline in freshwater availability across vast landmasses that represents one of the most alarming consequences of climate change. Recent satellite observations and scientific assessments reveal that this crisis is accelerating, threatening water security, agriculture, ecosystems, and global stability for billions of people.

The Scale of the Crisis

Groundbreaking research published in July 2025 in Science Advances, led by Arizona State University scientists, documents that Earth's continents have experienced unprecedented freshwater loss since 2002. The findings are stark: drying areas on land are expanding at a rate roughly twice the size of California every year, and 75% of the world's population—living in 101 countries—has been losing freshwater for the past 22 years.news.asu+2

The world is losing an estimated 324 billion cubic meters of freshwater annually, enough to meet the needs of 280 million people each year. This represents a 3% decline in global freshwater reserves, and the rate at which dry areas are getting drier now outpaces the rate at which wet areas are getting wetter, reversing long-standing hydrological patterns.policyedge+2

The Mega-Drying Phenomenon

Perhaps most concerning is the emergence of four continental-scale "mega-drying" regions, all located in the Northern Hemisphere. These vast zones represent areas where previously distinct drying hotspots have merged and interconnected, creating unprecedented water scarcity across enormous geographic areas.science+3

The Four Mega-Drying Regions:

Southwestern North America and Central America: This region encompasses major food-producing areas across the American Southwest, along with major desert cities such as Phoenix, Tucson, Las Vegas, Los Angeles, and Mexico City. Groundwater depletion in the Great Basin alone has resulted in the loss of 16.5 cubic miles (68.7 cubic kilometers) over two decades—roughly two-thirds as much water as California uses in a year. The lower Colorado River Basin has lost groundwater equivalent to the full capacity of Lake Mead, approximately 28 million acre-feet.earthobservatory.nasa+2

Alaska and Northern Canada: This region includes melting alpine glaciers in Alaska and British Columbia, snow and permafrost melting across the Canadian high latitudes, and drying in major agricultural regions such as British Columbia and Saskatchewan. Arctic lakes are drying up across the pan-Arctic region, contradicting earlier predictions that thawing permafrost would initially expand lakes.woodwellclimate+1

Northern Russia: Experiencing major snow and permafrost melting across the high latitudes, this region is undergoing dramatic landscape changes as ancient frozen ground thaws.news.asu

Middle East-North Africa (MENA) Pan-Eurasia: This massive region includes major desert cities like Dubai, Casablanca, Cairo, Baghdad, and Tehran; major food-producing regions including Ukraine, northwest India, and China's North China Plain; the shrinking Caspian and Aral Seas; and major metropolitan areas such as Barcelona, Paris, Berlin, Dhaka, and Beijing. The Arabian Aquifer System is losing terrestrial water storage at a rate of 0.64 ± 0.01 cm per year. Tehran faces a potential "day zero" scenario with dam reserves at historically low levels between 9-14% of capacity, and groundwater levels beneath the capital have sunk by about 12 meters in two decades.arabnews+2

Permanent Transformation of Land

A landmark December 2024 report from the UN Convention to Combat Desertification (UNCCD) revealed that 77.6% of Earth's land experienced drier conditions during the three decades leading up to 2020 compared to the previous 30-year period. Drylands have expanded by approximately 4.3 million km²—an area nearly a third larger than India—and now cover 40.6% of all land on Earth (excluding Antarctica).un

Unlike droughts, which are temporary, aridity represents a permanent transformation. "Droughts end. When an area's climate becomes drier, however, the ability to return to previous conditions is lost," explains Ibrahim Thiaw, UNCCD Executive Secretary. Some 7.6% of global lands—an area larger than Canada—have been pushed across aridity thresholds, transitioning from humid landscapes to drylands.un

Primary Drivers of Continental Drying

Groundwater Depletion: The research reveals that 68% of continental water loss comes from groundwater alone—a staggering finding that shows groundwater depletion now contributes more to sea level rise than glaciers and ice caps on land. Unsustainable extraction for agriculture, particularly irrigation, drives this depletion. In some regions, groundwater levels are dropping by 1-1.5 meters per year, as seen historically in China's North China Plain.latimes+4

Climate Change and Increased Evaporative Demand: Rising global temperatures are dramatically increasing the atmosphere's "thirst" for water. As temperatures climb, evaporative demand—the amount of moisture the atmosphere can extract from land, vegetation, and surface water—has been increasing over the last two decades. This intensification of the water cycle means that even when precipitation occurs, more water evaporates back into the atmosphere before it can recharge groundwater or support ecosystems.carbonbrief+1

A 2016 study in Nature demonstrated that land-atmosphere feedbacks amplify aridity increases, with soil moisture decreases, surface temperature changes, and reduced relative humidity combining to enhance continental drying. The physiological impact of increasing atmospheric CO₂ on vegetation exerts similar control on aridity.repository.library.noaa

Land-Atmosphere Feedbacks: Research shows that soil moisture changes create positive feedbacks that accelerate drying. When soil becomes drier, it leads to reduced cloud cover, greater surface solar radiation, more warming, and further decreases in precipitation—creating a self-reinforcing cycle. By 2015, continental water loss emerged as the leading driver of mass-driven global mean sea level rise, contributing 0.89 ± 0.15 mm per year—exceeding contributions from both the Greenland (0.73 ± 0.07 mm per year) and Antarctic (0.37 ± 0.05 mm per year) ice sheets.repository.library.noaa+1

Regional Impacts and Vulnerabilities

Europe and Mediterranean: Almost all of Europe (95.9% of its land) has experienced significant drying trends. By August 2025, 53% of Europe and the Mediterranean basin was affected by drought—an all-time high since records began in 2012. The Mediterranean, once considered an agricultural breadbasket, faces expansion of semi-arid conditions. Climate models project 20-30% declines in rainfall by mid-century, combined with sharp temperature increases.phys+2

North America: The southwestern United States and Mexico are experiencing aridity increases of 20-30% by 2070-2100 under moderate emissions scenarios, with the Chihuahuan and Sonoran deserts potentially seeing changes down to -40% under high emissions scenarios. Groundwater records from the last ice age reveal that aquifers in the U.S. Southwest are more sensitive to climate shifts than those in the Pacific Northwest, suggesting greater vulnerability to future warming.egusphere.copernicus+2

Central America: The region faces structural water security challenges, with demand highest in major cities located where supplies are historically lower. More than 1 million households survive on subsistence farming in the Dry Corridor, which spans over 30% of the region. The 2023-2024 drought left parts experiencing rainfall deficits of 50-75% of normal, with some Mexican areas seeing as low as 5-10% of normal rainfall.everstream+1

Asia: China's North China Plain, which accounts for 61% of the nation's wheat and 45% of maize yields, experienced groundwater table declines of 1-1.5 meters per year due to irrigation of winter wheat-summer maize double cropping systems. However, recent policy interventions show promise: since 2020, groundwater levels have increased at approximately 0.7 meters per year through extensive surface water diversion and strict groundwater extraction regulations.reddit+2

Middle East and North Africa: This region faces perhaps the most severe water crisis globally. Agriculture consumes the lion's share of water resources using outdated irrigation methods that result in enormous waste—billions of cubic meters lost annually in Iran alone. Groundwater dependence exceeds 90% for agricultural irrigation in countries like Saudi Arabia, with water tables declining over 100 meters in parts of the Saq-Ram Aquifer System.water.fanack+1

Consequences for Food Security and Agriculture

Continental drying poses an existential threat to global food security. Agriculture, which accounts for 70% of all freshwater withdrawals globally, is highly vulnerable to water shortages. One-quarter of the world's crops are grown in areas where water supply is highly stressed, highly unreliable, or both. Rice, wheat, and corn—which provide more than half the world's food calories—are particularly vulnerable, with 33% of these staple crops produced using highly stressed or highly variable water supplies.wri+1

Aridity-related land degradation affects approximately 40% of Earth's arable lands and is considered the world's single largest driver of agricultural systems degradation. Africa lost an estimated 12% of its GDP to rising aridity between 1990 and 2015 and is forecast to lose another 16% in the next half-decade. A World Bank simulation showed that a 100 mm decrease in rainfall in India, a key food producer, could reduce global real income by $68 billion.earth+1

The agricultural sector faces cascading impacts: reduced crop and livestock productivity, increased pest infestations, soil salinization (with roughly 10% of irrigated and rain-fed cropland already affected), and potential yield losses as high as 70% for crops like rice and beans in the most impacted countries.nationalobserver+1

Migration, Displacement, and Social Impacts

Water deficits are linked to 10% of the rise in global migration. Forced migration represents one of aridity's most visible consequences. As land becomes uninhabitable due to water scarcity and agricultural collapse, families and entire communities have no choice but to abandon their homes. From the Middle East to Africa and South Asia, millions are already on the move—a trend set to intensify in coming decades.worldbank+2

In worst-case scenarios, projections suggest up to 5 billion people could live in drylands by the century's end, grappling with depleted soils, dwindling water resources, and ecosystem collapse. Droughts in Sub-Saharan Africa alone are estimated to leave between 600,000 to 900,000 people jobless each year.policyedge+1

Irreversible Changes and Tipping Points

Perhaps most alarming, scientists warn that many observed changes may be permanent or irreversible on human timescales. Research published in Science in March 2025 found that Earth has lost enough soil moisture in the last 40 years to change the planet's spin and shift the location of the North Pole. The study provides "robust evidence of an irreversible shift in terrestrial water sources under the present changes in climate," according to hydrology researcher Luis Samaniego.insideclimatenews+1

The research identified a critical tipping point around 2014-15 during "mega El Niño" years, when climate extremes began accelerating and groundwater use increased dramatically. After this point, continental drying exceeded the rates of glacier and ice sheet melting, and drying regions flipped from being located mostly in the Southern Hemisphere to mostly in the north.news.asu

In regions experiencing extended droughts, recovering from water deficits would require well above average rainfall for 10 consecutive years—a scenario researchers describe as highly unlikely. "It's permanent, at least for our time scale," Samaniego noted.insideclimatenews

Policy Solutions and Path Forward

The World Bank's inaugural Global Water Monitoring Report, titled "Continental Drying: A Threat to Our Common Future" and released in November 2025, provides a comprehensive roadmap for addressing the crisis. The report recommends a three-pronged approach: managing demand, augmenting water supply, and improving water allocation.worldbank+2

Five Cross-Cutting Levers:

Strengthening Institutions: Developing robust governance structures for water resource management, with participatory decision-making and equitable access.openknowledge.worldbank+1

Reforming Water Tariffs and Repurposing Subsidies: Implementing pricing mechanisms that reflect the true scarcity and value of water. Tiered pricing systems that charge progressively higher rates as consumption increases have proven effective in discouraging excessive groundwater extraction.researchfloor

Adopting Water Accounting: Implementing comprehensive monitoring systems using satellite data and ground-based observations to track water resources at county and regional levels.worldbank

Leveraging Data and Technological Innovations: Utilizing remote sensing, artificial intelligence, machine learning, and smart irrigation systems to optimize groundwater usage and monitor extraction.researchfloor

Valuing Water in Trade: Addressing the practice of "virtual water trade," where water-scarce countries continue to export water-intensive products, thereby exacerbating domestic water stress.policyedge

Success Stories and Mitigation Potential

Despite the dire outlook, examples of successful intervention demonstrate that reversing groundwater depletion is achievable through coordinated action. China's North China Plain represents a striking success story: through extensive surface water diversion from wetter southern regions, strict regulations on groundwater extraction, and enhanced environmental water allocations exceeding 7 cubic kilometers since 2021, groundwater levels have risen at approximately 0.7 meters per year since 2020, exceeding 2005 levels by 2024. This recovery occurred across approximately 130,000 square kilometers, demonstrating that significant and rapid groundwater recovery is possible through focused policy initiatives.nature+1

While efforts to mitigate climate change face challenges, scientists emphasize that addressing continental drying through improved groundwater management is immediately actionable. "We can address continental drying by implementing new policies around regional and international groundwater sustainability," noted Jay Famiglietti. "In turn, this will slow the rate of sea-level rise and help preserve water for future generations".news.asu

Conclusion

Continental drying represents a planetary emergency that demands immediate, coordinated global action. The convergence of climate change, unsustainable groundwater extraction, and poor water management has created what scientists describe as potentially "the most alarming message yet about the impact of climate change on our water resources". With 75% of humanity already experiencing freshwater losses and projections suggesting conditions will worsen substantially without intervention, the stakes could not be higher.phys+1

The crisis threatens food security for billions, drives mass migration, contributes significantly to sea level rise, and could push societies toward tipping points where adaptation becomes increasingly difficult. Yet the availability of detailed satellite monitoring, proven policy solutions, and successful case studies like China's North China Plain recovery demonstrate that reversing these trends remains possible. What's required now is the political will to implement comprehensive water management reforms, sustainable agricultural practices, and international cooperation—before permanent, irreversible damage to Earth's hydrological systems becomes inevitable.

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Wednesday, November 5, 2025

New Climate Change call: Continental Drying