Aridity, an “existential crisis” reshaping life on Earth, could impact five billion people by 2100.
Dramatic water-related disasters, such as floods and storms, have intensified in parts of the world, yet more than three-quarters of Earth’s land has become permanently drier in recent decades, UN scientists reported in a new analysis.
The landmark report from the UN Convention to Combat Desertification (UNCCD) revealed that 77.6% of Earth’s land experienced increased dryness in the three decades leading up to 2020, compared to the preceding 30-year period.
During the same timeframe, drylands expanded by approximately 4.3 million square kilometers—an area almost one-third larger than India, the world’s 7th largest country. These drylands now encompass 40.6% of Earth’s land area, excluding Antarctica.
Moreover, 7.6% of global lands—an area exceeding the size of Canada—crossed critical aridity thresholds. This shift involved regions transitioning from non-drylands to drylands or moving into more arid categories within existing drylands.
Most of these areas have transitioned from humid landscapes to drylands, with dire implications for agriculture, ecosystems, and the people living there.
And the research warns that, if the world fails to curb greenhouse gas emissions, another 3% of the world’s humid areas will become drylands by the end of this century.
In high greenhouse gas emissions scenarios, expanding drylands are forecast across the Midwestern United States, central Mexico, northern Venezuela, north-eastern Brazil, south-eastern Argentina, the entire Mediterranean Region, the Black Sea coast, large parts of southern Africa, and southern Australia.
The report, The Global Threat of Drying Lands: Regional and global aridity trends and future projections, was launched at the 16th conference of UNCCD’s nearly 200 Parties in Riyadh, Saudi Arabia (COP16), the largest UN land conference to date, and the first UNCCD COP to be held in the Middle East, a region profoundly affected by impacts from aridity.
“This analysis finally dispels an uncertainty that has long surrounded global drying trends,” says Ibrahim Thiaw, UNCCD Executive Secretary. “For the first time, the aridity crisis has been documented with scientific clarity, revealing an existential threat affecting billions around the globe.”
“Unlike droughts—temporary periods of low rainfall—aridity represents a permanent, unrelenting transformation,” he adds. “Droughts end. When an area’s climate becomes drier, however, the ability to return to previous conditions is lost. The drier climates now affecting vast lands across the globe will not return to how they were and this change is redefining life on Earth.”
The report by UNCCD Science-Policy Interface (SPI) — the UN body for assessing the science of land degradation and drought — points to human-caused climate change as the primary driver of this shift. Greenhouse gas emissions from electricity generation, transport, industry, and land use changes warm the planet, and other human activities warm the planet and affect rainfall, evaporation, and plant life, creating the conditions that increase aridity.
Global aridity index (AI) data track these conditions and reveal widespread change over the decades.
Aridification hotspots
Areas particularly hard-hit by the drying trend include almost all of Europe (95.9% of its land), parts of the western United States, Brazil, parts of Asia (notably eastern Asia), and central Africa.
- Parts of the Western United States and Brazil: Significant drying trends, with water scarcity and wildfires becoming perennial hazards.
- Mediterranean and Southern Europe: Once considered agricultural breadbaskets, these areas face a stark future as semi-arid conditions expand.
- Central Africa and parts of Asia: Biologically megadiverse areas are experiencing ecosystem degradation and desertification, endangering countless species.
By contrast, less than a quarter of the planet’s land (22.4%) experienced wetter conditions, with areas in the central United States, Angola’s Atlantic coast, and parts of Southeast Asia showing some gains in moisture.
The overarching trend, however, is clear: drylands are expanding, pushing ecosystems and societies to suffer from aridity’s life-threatening impacts.
The report names South Sudan and Tanzania as nations with the largest percentage of land transitioning to drylands, and China as the country experiencing the largest total area shifting from non-drylands into drylands.
For the 2.3 billion people – well over 25% of the world’s population – living in the expanding drylands, this new normal requires lasting, adaptive solutions. Aridity-related land degradation, known as desertification, represents a dire threat to human well-being and ecological stability.
And as the planet continues to warm, report projections in the worst-case scenario suggest up to 5 billion people could live in drylands by the century’s end, grappling with depleted soils, dwindling water resources, and the diminishment or collapse of once-thriving ecosystems.
Forced migration is one of aridity’s most visible consequences. As land becomes uninhabitable, families and entire communities facing water scarcity and agricultural collapse often have no choice but to abandon their homes, leading to social and political challenges worldwide. From the Middle East to Africa and South Asia, millions are already on the move—a trend set to intensify in coming decades.
Aridity’s devastating impact
The effects of rising aridity are cascading and multifaceted, touching nearly every aspect of life and society, the report says.
It warns that one-fifth of all land could experience abrupt ecosystem transformations from rising aridity by the end of the century, causing dramatic shifts (such as forests becoming grasslands and other changes) and leading to extinctions among many of the world’s plants, animals, and other life.
- Aridity is considered the world’s largest single driver behind the degradation of agricultural systems, affecting 40% of Earth’s arable lands
- Rising aridity has been blamed for a 12% decline in gross domestic product (GDP) recorded for African countries between 1990–2015
- More than two-thirds of all land on the planet (excluding Greenland and Antarctica) is projected to store less water by the end of the century, if greenhouse gas emissions continue to rise even modestly
- Aridity is considered one of the world’s five most important causes of land degradation (along with land erosion, salinization, organic carbon loss, and vegetation degradation)
- Rising aridity in the Middle East has been linked to the region’s more frequent and larger sand and dust storms
- Increasing aridity is expected to play a role in larger and more intense wildfires in the climate-altered future—not least because of its impacts on tree deaths in semi-arid forests and the consequent growing availability of dry biomass for burning
- Rising aridity’s impacts on poverty, water scarcity, land degradation, and insufficient food production have been linked to increasing rates of sickness and death globally —especially among children and women
- Rising aridity and drought play a key role in increasing human migration around the world—particularly in the hyper-arid and arid areas of southern Europe, the Middle East, North Africa, and southern Asia.
Report marks a turning point
For years, documenting the rise of aridity proved a challenge, the report states. Its long-term nature and the intricate interplay of factors such as rainfall, evaporation, and plant transpiration made analysis difficult. Early studies produced conflicting results, often muddied by scientific caution.
The new report marks a turning point, leveraging advanced climate models and standardized methodologies to deliver a definitive assessment of global drying trends, confirming the inexorable rise of aridity, while providing critical insights into its underlying drivers and potential future trajectory.
Recommendations
The report offers a comprehensive roadmap for tackling aridity, emphasizing both mitigation and adaptation. Among its recommendations:
- Strengthen aridity monitoring
Integrate aridity metrics into existing drought monitoring systems. This approach would enable early detection of changes and help guide interventions before conditions worsen. Platforms like the new Aridity Visual Information Tool provide policymakers and researchers with valuable data, allowing for early warnings and timely interventions. Standardized assessments can enhance global cooperation and inform local adaptation strategies. - Improve land use practices
Incentivizing sustainable land use systems can mitigate the impacts of rising aridity, particularly in vulnerable regions. Innovative, holistic, sustainable approaches to land management are the focus of another new UNCCD SPI report, Sustainable Land Use Systems: The path to collectively achieving Land Degradation Neutrality. It considers how land-use at one location affects others elsewhere, makes resilience to climate change or other shocks a priority, and encourages participation and buy-in by Indigenous and local communities as well as all levels of government. Projects like the Great Green Wall—a land restoration initiative spanning Africa—demonstrate the potential for large-scale, holistic efforts to combat aridity and restore ecosystems, while creating jobs and stabilizing economies. - Invest in water efficiency
Technologies such as rainwater harvesting, drip irrigation, and wastewater recycling offer practical solutions for managing scarce water resources in dry regions. - Build resilience in vulnerable communities
Local knowledge, capacity building, social justice, and holistic thinking are vital to resilience. Sustainable land use systems encourage decision-makers to apply responsible governance, protect human rights (including secure land access), and ensure accountability and transparency. Capacity-building programs, financial support, education programs, climate information services, and community-driven initiatives empower those most affected by aridity to adapt to changing conditions. Farmers switching to drought-resistant crops or pastoralists adopting more arid-tolerant livestock exemplify incremental adaptation. - Develop international frameworks and cooperation
The UNCCD’s Land Degradation Neutrality framework provides a model for aligning national policies with international goals, ensuring a unified response to the crisis. National Adaptation Plans must incorporate aridity alongside drought planning to create cohesive strategies that address water and land management challenges. Cross-sectoral collaboration at the global level, facilitated by frameworks like the UNCCD, is essential for scaling solutions.
Comments
“For decades, the world’s scientists have signaled that our growing greenhouse gas emissions are behind global warming. Now, for the first time, a UN scientific body is warning that burning fossil fuels is causing permanent drying across much of the world, too—with potentially catastrophic impacts affecting access to water that could push people and nature even closer to disastrous tipping points. As large tracts of the world’s land become more arid, the consequences of inaction grow increasingly dire and adaptation is no longer optional—it is imperative.”
UNCCD Chief Scientist Barron Orr
“Without concerted efforts, billions face a future marked by hunger, displacement, and economic decline. Yet, by embracing innovative solutions and fostering global solidarity, humanity can rise to meet this challenge. The question is not whether we have the tools to respond—it is whether we have the will to act.”
Nichole Barger, Chair, UNCCD Science-Policy Interface
The report’s clarity is a wake-up call for policymakers: tackling aridity demands more than just science—it requires a diversity of perspectives and knowledge systems. By weaving Indigenous and local knowledge with cutting-edge data, we can craft stronger, smarter strategies to slow aridity’s advance, mitigate its impacts, and thrive in a drying world.”
Sergio Vicente-Serrano, co-lead author of the report and an aridity expert with Spain’s Pyrenean Institute of Ecology
“This report underscores the critical need to address aridity as a defining global challenge of our time. By uniting diverse expertise and leveraging breakthrough technologies, we are not just measuring change—we are crafting a roadmap for resilience. Tackling aridity demands a collaborative vision that integrates innovation, adaptive solutions, and a commitment to securing a sustainable future for all.”
Narcisa Pricope, co-lead author, professor of geosciences and associate vice president for research at Mississippi State University
“The timeliness of this report cannot be overstated. Rising aridity will reshape the global landscape, challenging traditional ways of life and forcing societies to reimagine their relationship with land and water. As with climate change and biodiversity loss, addressing aridity requires coordinated international action and an unwavering commitment to sustainable development.”
Andrea Toreti, co-lead author and senior scientist, European Commission’s Joint Research Centre
Reference: “The Global Threat of Drying Lands: Regional and global aridity trends and future projections” by Vicente-Serrano, S. M., N. G. Pricope, A. Toreti,, E. Morán-Tejeda, J. Spinoni, A. Ocampo-Melgar,
E. Archer, A. Diedhiou, T. Mesbahzadeh, N. H. Ravindranath, R. S. Pulwarty and S. Alibakhshi, 2024, United Nations.
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18 Comments
“…, yet more than three-quarters of Earth’s land has become permanently drier in recent decades, …”
How long does “permanently” last? Until the 12th of Never?
https://news.yahoo.com/news/officials-stunned-iconic-lake-sees-111531055.html
Note all the trees.
This argument is like pointing out one snowed over car, and arguing that there’s no global warming. Nice try.
You misunderstand. The article talks about “aridity thresholds,” and states, “The new report marks a turning point, leveraging advanced climate models and standardized methodologies to deliver a definitive assessment of global drying trends, confirming the inexorable rise of aridity, while providing critical insights into its underlying drivers and potential future trajectory.” It unequivocally states, “When an area’s climate becomes drier, however, the ability to return to previous conditions is lost.”
I didn’t mention warming. I was addressing aridity, which may happen without warming. The point is, an example of an area experiencing long-term drought, and rebounding, raises the question of whether the claim is valid. This article doesn’t provide sufficient information for the reader to determine whether Lake Oroville qualifies as an example of ‘irreversible’ aridity or simply a ‘common’ drought; although, their claims suggest that the mechanism of drought should drive an area to aridity even with just droughts. The linked article seems to make the point that droughts are directly responsible for aridity.
I realize that a single example rarely proves a thesis, except when the thesis says the example should be impossible, in which case the thesis is disproven.
https://scitechdaily.com/from-parched-to-overflow-how-record-breaking-rains-revived-lake-casitas/
Riiiight. So, when they say the drying is permanent, you want to know which 12th it’ll end. The evidence of climate change is overwhelming. Which is why science deniers like you have to resort to bullsh1t arguments to deny it. If you had better arguments, you’d write science papers to show those other scientists how wrong they are.
To me, the word “permanent” means the original conditions will never, ever return. The geologic history of Earth destroys the idea that if any general geomorphic feature or climate type disappears, it is never replaced. (The Oxygen Revolution is probably the only valid example of a so-called Tipping Point.) If that were the case, the whole Earth would be a desert according to the authors who claim that once aridity is reached, the former conditions cannot return.
Tell me how your arguments are of higher quality than mine. All I see in your remarks are unsupported assertions and insults. The evidence is hardly “overwhelming” when Nobel Laureates and distinguished emeritus professors challenge the claims. Science is not about a political consensus, but about replicatable experiments and provable facts. If you had better arguments, you would actually state them, instead of attacking me.
As to writing those “science papers, were I still an academic, I would have a department publishing budget and be expected to publish. As it is, being retired, there are no expectations to “publish or perish.” So, I seek out cost effective ways to counter poorly researched work that frequently contains unsupportable claims of illogical conclusions. You engage in what is little more than arm waving and regurgitation of things that you have read, but I doubt you actually understand.
The Scientific Method involves observations and measurements to gather facts, inductive reasoning to develop multiple working hypotheses, and the design of experiments to invalidate selected null-hypotheses. The results are preferred to be expressed with mathematics or statistics to validate the conclusions, not arm waving based on beliefs in poor quality, qualitative work. The essence of the validation of science is when it is peer reviewed, which means published in a journal commonly read by peers in the discipline, not what has been pal-reviewed by gate-keepers who are motivated to maintain their own reputation more than they are the reputation of the publisher(s).
Why are you sufficiently incensed by my questions to personally attack me rather than attack my questions and point out how and why they are wrong? The commonly accepted answer is that it is because the only arrow you have in your quiver is insult.
“When an area’s climate becomes drier, however, the ability to return to previous conditions is lost.”
Then why did lakes develop recently in the Sahara for the first time in 50 years. To say something will happen, without even defining what is meant, is scaremongering.
If the quote above is true, how is it that NASA has documented ‘greening’ of several percent in the world?
The Sahara still remains a desert. From time to time lakes form in deserts, yet these occurrences are very rare and most of the water quickly evaporates. Small quantities of water do eventually reach underground aquifers, but this takes an extraordinarily long time, so such desert aquifers take a long time to recharge. Without a high fresh-water table, vegetation can only survive within ecological niches in relatively small numbers. Also, due to the low average rainfall, the number and spread of plants remains below a level which can hold the sand together, and soil and clay cannot form to provide nourishing and fertile soils. Erosion and movement of sand become permanent fixtures. Deserts tend to grow in size and their outer boundaries expand. Dunes move.
“In high greenhouse gas emissions scenarios, …”
Again, a term is used without defining it. Are the authors referring to the RCP8.5 or SSP 8.5 (either or both) scenarios? Recent analyses of these effectively ‘Business as Usual’ scenarios have pointed out that they are improbable because there aren’t sufficient fossil fuel resources. They are essentially self-limiting, yet are still being used. Where are the disclaimers about the long-term improbability of these scenarios?
https://www.carbonbrief.org/explainer-the-high-emissions-rcp8-5-global-warming-scenario/
Without numbers to support the probability (and uncertainty envelope) of these scenarios, they are little more than arm waving.
As average temperatures increase, areas with lower rainfall experience drying soils which changes the types of plants which can grow in those areas. This makes those areas more fire prone as more grasses and shrubs which can survive in low rainfall environments become more common. Trees begin to die off providing more area for these more flammable grasses and scrub lands to take over. Local availability of water also declines as the snow-pack at higher altitudes leads to a decline in melt-water run-off into rivers and streams.
The world has witnessed a tenfold increase in the number of natural disasters since the 1960s.
The cost of these disasters is also increasing leading to trillions of dollars in losses.
https://www.latimes.com/environment/story/2022-06-30/aridification-kills-civilizations-is-california-next
An important point ignored by the authors is that the Clausius–Clapeyron relation predicts that as the atmosphere warms, the capacity for holding water vapor will increase, and therefore evaporation will increase. [The commonly used words, “could, may, might, possibly, that alarmists are so fond of would be appropriate here.] That increased water vapor WILL precipitate out in a short time. Thus, water isn’t actually becoming less abundant. WHERE the water precipitates MAY change, but the principles of orographic precipitation aren’t going to change. Therefore, it would be more accurate to say that some areas will see increases in precipitation, while others will experience a decrease, with an increase overall.
This supposed technical article reads more like an investment prospectus than the technical article it purports to be, complete with marketing buzzword such as, “Indigenous and local knowledge with cutting-edge data.” Gag me with a spoon!
The water will precipitate as more intense rainfall. Warmer air holds more moisture, which leads to increased flooding. Such individual flooding events are harder to predict. Unfortunately many of these events will take place in areas already susceptible to flooding, rather than areas experiencing reduced rainfall. Groundwater reserves in many drought affected areas are already facing overuse due to the extremely long time they require to recharge. The reductions in rainfall increase the pressure on these important sources of water for broadacre cropping. 40% of agricultural land is degraded, in line with the long term trend.
Conflict is also exacerbating reductions in the global staple food supply as farmers abandon their land. Seed programs that ensure resilient seed stock are disrupted in many regions where conflict occurs, which are essential for maintaining viable yields. To prevent further declines, a global seed exchange is required.
Thank you, Clyde, for the good work you’re doing.
As soon as I see an environmental article on this site, I scroll down to your comments. There’s more valuable info in your brief remarks than in the entire body of the article.
Thank you, Boba.
The article refers to “aridity”, how dry and salty land is. As the salinity of land increases, agriculture becomes increasingly difficult. Combined with drier soils, farming such areas eventually becomes impossible. Not only is this an increasing trend, but the average temperature of winters in many agricultural regions have become warmer. Without enough “chilling hours” during winter, many varieties of fruit tree do not produce a crop.
A lot of the food you take for granted is becoming increasingly difficult to produce, and losses in production as well as increasing expense, combined with supermarket concentration, makes farming a losing proposition for many of us who produce your food. Our communities suffer as our friends and neighbours leave permanently.
Increased evaporation leads to drier soils and drier plant matter. This increases the risks of fire. It also leads to drier skin and increased risk of heat stroke, as it is more difficult for the human body to cool itself. That is why they put out those warnings for heat waves and encourage the increased consumption of water.
Increased humidity prevents sweat from adequately cooling the body. Even though you may sweat more in humid weather, it has a reduced effect as the air is already saturated. Your sweat glands also reduce in function as you age, and as a result your body directs more blood flow to your skin, which causes greater strain on your heart and other internal organs. Due to the saturation of the air, the sweat cannot evaporate from your skin, which in turn increases your body temperature. Your heart works harder in an attempt to cool itself.
If the increased evaporation lead to increases in localized rainfall, it might mitigate fire risk or cool the air, but unfortunately more often than not, the rainfall mostly occurs in other areas where the air temperature is already cooler. This usually happens a long distance from where localized evaporation occurs, as it takes time for rising moisture to accumulate and form clouds, then condense and cool enough to fall. This is often influenced by geography, topography and distance from the coastline, a complex process influenced by air movements and land and sea surface temperatures. Cleared land and deserts for example, have warmer surface areas.