In a sobering revelation from the United Nations Convention to Combat Desertification (UNCCD), scientists have documented a dramatic shift in Earth’s climate: over three-quarters of the planet’s land has experienced a permanent drying trend in the last 30 years. This finding, detailed in the report The Global Threat of Drying Lands: Regional and Global Aridity Trends and Future Projections, was unveiled at the 16th Conference of Parties (COP16) in Riyadh, Saudi Arabia—the largest UN land conference to date.
The report states that 77.6% of Earth’s land became permanently drier between 1990 and 2020 compared to the previous three decades. Concurrently, drylands expanded by 4.3 million square kilometers, an area almost a third larger than India, and now encompass 40.6% of Earth’s landmass (excluding Antarctica). Most strikingly, approximately 7.6% of global lands- an area larger than Canada- crossed critical aridity thresholds, transitioning from humid to dry conditions or from less to more arid classifications.
“This analysis finally dispels uncertainty surrounding global drying trends,” remarked Ibrahim Thiaw, UNCCD Executive Secretary. “Aridity represents a permanent transformation, unlike temporary droughts. The drier climates now affecting vast lands across the globe will not return to how they were, redefining life on Earth.”
The Role of Human-Caused Climate Change
The report identifies greenhouse gas emissions as the primary driver of this shift. Activities such as electricity generation, transportation, industrial processes, and land use changes are warming the planet, altering rainfall patterns, increasing evaporation rates, and affecting vegetation- all of which contribute to aridity. Advanced climate models and global aridity index (AI) data were used to track these changes and confirm the alarming trends.
Aridification hotspots include vast regions across Europe (95.9% affected), parts of the western United States, Brazil, southern Africa, and Asia. Mediterranean nations, once agricultural powerhouses, are now grappling with semi-arid conditions. In South Sudan and Tanzania, a significant portion of land has transitioned to drylands, while China has seen the largest absolute area shift.
By contrast, only 22.4% of global land experienced wetter conditions during this period, with regions like the central United States and parts of Southeast Asia showing modest gains in moisture. However, the overarching trend is clear: drylands are expanding, jeopardising ecosystems, agriculture, and human livelihoods.
The implications of rising aridity are profound, touching every aspect of life and society:
Agriculture: Aridity is the leading driver of land degradation, impacting 40% of Earth’s arable lands. This has contributed to a 12% decline in GDP across African nations between 1990 and 2015. Projected crop losses include 20 million tons of maize, 21 million tons of wheat, and 19 million tons of rice globally by 2040.
Water Resources: More than two-thirds of the planet’s land is projected to store less water by 2100, even under moderate emissions scenarios. Regions such as the Middle East have already experienced a 75% decline in water availability since the 1950s.
Biodiversity: Rising aridity threatens the survival of 55% of species in arid and humid regions, risking the transformation of ecosystems as forests give way to grasslands and other landscapes.
Human Migration: Aridity-induced land degradation and water scarcity are driving forced migration, particularly in hyper-arid and arid regions of southern Europe, the Middle East, and North Africa. By 2100, up to 5 billion people- over half the projected global population- could be living in drylands under the worst-case climate scenarios.
Health: The cascading impacts of aridity exacerbate global health challenges, from malnutrition to respiratory illnesses caused by increased dust storms.
Recommendations for Action
The UNCCD report outlines a comprehensive roadmap to mitigate the effects of aridity and adapt to its impacts:
Strengthen Aridity Monitoring: Integrate aridity metrics into drought monitoring systems to enable early detection and guide timely interventions. Tools like the Aridity Visual Information Tool provide valuable insights for policymakers.
Sustainable Land Use Practices: Incentivise holistic land management approaches that emphasise resilience and participation by Indigenous and local communities. Initiatives like Africa’s Great Green Wall demonstrate the potential for large-scale restoration projects to combat desertification and create economic opportunities.
Invest in Water Efficiency: Technologies such as rainwater harvesting, drip irrigation, and wastewater recycling offer practical solutions for managing scarce water resources in affected regions.
Build Community Resilience: Empower vulnerable communities through education, capacity building, and financial support. Encouraging practices such as planting drought-resistant crops and adopting arid-tolerant livestock can enhance local adaptation.
International Cooperation: Align national policies with global frameworks like the UNCCD’s Land Degradation Neutrality framework to foster collaborative solutions. Cross-sectoral partnerships are essential to scale interventions and ensure a unified global response.
“For decades, scientists have warned about the dire consequences of greenhouse gas emissions,” noted Nichole Barger, Chair of the UNCCD Science-Policy Interface. “This report underscores the urgent need for global solidarity and innovative solutions. The question is not whether we have the tools to respond- it is whether we have the will to act.”
As the world confronts an escalating aridity crisis, the choices made today will determine the future of billions of people and the planet itself. The report’s findings are a wake-up call for policymakers, scientists, and communities to unite in combating this existential threat and securing a sustainable future.