Scientists Project Arid Landscapes Could Expand Across 40 Percent of the Globe by 2100

Arid landscapes are poised to spread significantly over the coming decades, potentially encompassing roughly 40 percent of the Earth's total land area by the end of the 21st century. This impending ecological transformation threatens to alter natural habitats, deplete vital freshwater supplies, and disrupt agricultural communities around the world.

According to a study published in the scientific journal Environmental Research Letters and covered by ScienceAlert, global drylands are on track to undergo a substantial redistribution. The researchers modeled these landscape shifts by analyzing extensive meteorological datasets spanning from 1960 through 2023 in conjunction with sophisticated CMIP6 climate projections.

The findings indicate that dryland coverage across the planet—measured outside of the Antarctic continent—stood at approximately 38.58 percent during the 1994 to 2023 baseline reference window. Over the final three decades of this century, between 2071 and 2100, that proportion is anticipated to climb to between 39.31 percent and 40.28 percent.

At the highest end of the researchers' forecast, this outward creep would consume an additional 915,000 square miles, or roughly 2.37 million square kilometers, of land compared to the baseline era. Such a massive geographic shift would place immense pressure on regional biodiversity, altering the fundamental structure of terrestrial biomes.

Within the framework of the study, the research team identified dryland regions using a standardized aridity index threshold set below 0.65. This metric defines an arid environment by calculating the ratio between the volume of incoming precipitation and the amount of water lost to the atmosphere through surface evaporation and plant transpiration.

Interestingly, the investigators noted that elevated atmospheric carbon dioxide—the primary driver of rising global temperatures—exerts a complex, dual effect on landscape drying. Under specific circumstances, elevated concentrations of carbon dioxide may actually slow the rate of dryland expansion by causing vegetation to partially close its microscopic leaf pores, known as stomata.

When plants constrict their stomata in carbon-rich air, they release less moisture back into the atmosphere via transpiration. The study's authors highlighted that traditional climate projections have frequently omitted these plant-level carbon dioxide responses on potential evapotranspiration, a gap that could lead to inflated aridity estimates or inaccurate geographic mapping of future dryland hotspots.

Despite this moderating physiological factor, hyper-arid territories are still forecast to register the largest overall expansion among all dryland categories. These extreme zones face intensifying dryness that will leave fragile ecosystems with virtually no margin for resilience or natural recovery.

Geographically, Australia is projected to experience the most acute and severe dryland transformation on the planet. Brazil is anticipated to suffer the second-highest level of dryland growth, while substantial territories across the African continent are also slated to undergo major aridification.

Other major global powers and regions are already dealing with vast arid zones that could see further pressure. The research highlights that both China and Russia manage wide expanses of dry sub-humid territory, while nations such as Algeria, Libya, and Saudi Arabia encompass vast, hyper-arid deserts.

The authors warned that the intrusion of dryland climatic conditions into previously humid or temperate regions will aggravate water scarcity, accelerate ecosystem degradation, and trigger wider desertification. These intersecting pressures present profound obstacles to international sustainability targets and long-term socio-economic stability.

The real-world impacts of this drying trend are already visible across vulnerable farming communities, where ongoing soil degradation continues to diminish the supply of productive, arable land. In some severely affected regions, catastrophic drought conditions have degraded once-fertile landscapes into barren territory, driving humanitarian crises and displacing families.

Underlying these widespread ecological disruptions is ongoing human activity, which continues to drive up global temperatures and intensify atmospheric evaporative demand. As the atmosphere warms, it pulls increasing amounts of moisture from soils and water bodies, steadily pushing borderline territories past critical aridity thresholds.

To mitigate these dangerous long-term outcomes, scientists emphasize that the most essential step is an aggressive and rapid reduction in planet-warming greenhouse gas pollution. Curbing emissions at the source remains the single most effective way to slow down the relentless expansion of global dryland boundaries.

Alongside global emissions reductions, localized land stewardship and conservation strategies are crucial for safeguarding vulnerable terrain. Initiatives such as restoring native plant cover, undertaking reforestation projects, controlling soil erosion, and revitalizing natural watersheds can dramatically enhance the resilience of the landscape.

Maintaining healthy, organic-rich soil allows the ground to retain greater quantities of water, nourish sustained plant life, and withstand prolonged periods of drought. As dry conditions continue to advance, the research team underscored the urgent need for updated mapping and ongoing evaluations of dryland redistributions to effectively guide future climate adaptation initiatives.