Even as dramatic water-related disasters such as floods and storms intensified in some parts of the world, more than three-quarters of Earth’s land became permanently drier in recent decades, UN scientists have warned in a stark new analysis released on Monday, December 9, 2024.

Some 77.6% of Earth’s land experienced drier conditions during the three decades leading up to 2020 compared to the previous 30-year period, according to the landmark report from the UN Convention to Combat Desertification (UNCCD).

Over the same period, drylands expanded by about 4.3 million km2 – an area nearly a third larger than India, the world’s 7th largest country – and now cover 40.6% of all land on Earth (excluding Antarctica).

In recent decades some 7.6% of global lands – an area larger than Canada – were pushed across aridity thresholds (i.e. from non-drylands to drylands, or from less arid dryland classes to more arid classes).

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.

The report offers a comprehensive roadmap for tackling aridity, emphasising both mitigation and adaptation.

UNCCD Chief Scientist, Barron Orr, said: “For decades, the world’s scientists have signalled 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.”

Nichole Barger, Chair, UNCCD Science-Policy Interface, said: “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.”

Sergio Vicente-Serrano, co-lead author of the report and an aridity expert with Spain’s Pyrenean Institute of Ecology, said: “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.”

Narcisa Pricope, co-lead author, professor of geosciences and associate vice president for research at Mississippi State University, USA, said; “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.”

Andrea Toreti, co-lead author and senior scientist, European Commission’s Joint Research Centre, said: “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.”