Global Drylands Projected to Encompass 40 Percent of Earth's Landmass by 2100, Study Warns

Arid and semi-arid landscapes are poised to claim a significantly larger portion of the planet over the coming decades. According to newly published scientific modeling, drylands could spread across roughly 40 percent of Earth’s terrestrial surface by the close of the 21st century, posing severe challenges to global agriculture, water supplies, and fragile ecosystems.

The findings, published in the scientific journal Environmental Research Letters, detail how shifting climate patterns are altering the global landscape. Researchers determined that between 1994 and 2023, drylands made up approximately 38.58 percent of Earth’s land surface outside of Antarctica. However, projections for the period spanning 2071 to 2100 indicate that this coverage could climb to between 39.31 percent and 40.28 percent.

At the upper boundary of those projections, the geographic expansion represents an addition of roughly 915,000 square miles, or 2.37 million square kilometers, of dry territory when measured against the modern baseline. Within this expanding footprint, researchers found that hyper-arid zones are expected to experience the most pronounced territorial increase.

To generate these estimates, the research team analyzed historical meteorological records spanning from 1960 to 2023 alongside advanced CMIP6 climate models. The researchers categorized regions using an aridity index, setting a threshold of 0.65 to identify drylands. This metric evaluates areas where precipitation levels are notably low compared to the rate of moisture lost through surface evaporation and plant transpiration.

The investigation also highlighted an intricate physiological feedback loop involving atmospheric carbon dioxide. While rising greenhouse gas levels are the primary engine behind ascending global temperatures, elevated carbon concentrations can concurrently trigger plants to partially close their microscopic leaf pores, known as stomata. This response curbs the volume of water lost through transpiration, slightly tempering the projected expansion of drylands in certain scenarios.

Because older modeling frameworks did not always incorporate the biological influence of carbon dioxide on potential evapotranspiration, previous evaluations may have produced elevated aridity projections and mischaracterized hotspot patterns. Accounting for these plant-level reactions provides scientists with a more nuanced understanding of how aridity shifts will unfold geographically.

Geographically, the study projects that Australia will endure the most intense arid transitions of any country on Earth. Brazil is expected to face the second-most severe dryland shift, with various parts of the African continent also predicted to undergo major environmental transformations.

The research also mapped the existing distribution of different aridity categories across the globe. Nations such as China and Russia encompass vast dry sub-humid territories, whereas hyper-arid environments are heavily concentrated in Middle Eastern and North African countries, including Algeria, Libya, and Saudi Arabia.

The broader ecological consequences of this geographic creep could be severe. As dryland conditions advance into regions that historically enjoyed higher humidity, the shift is expected to exacerbate regional water shortages, accelerate the breakdown of ecosystems, and hasten the spread of desertification across previously fertile terrain.

These expanding dry zones will place immense strain on vulnerable communities and agricultural systems. When arid conditions intensify, arable cropland begins to degrade, leaving farmers with diminishing yields and tightening the margin of survival for populations that are already dealing with acute water stress.

The human cost of accelerating dryness is already evident across several vulnerable regions worldwide. In farming sectors facing declining soil productivity and persistent droughts, agricultural land is rapidly shrinking, while severe water shortages have driven displacement, such as pushing displaced Syrian families into Jordan as barren conditions take over.

Underlying these widespread shifts is human activity, which continues to generate the emissions driving global warming. Rising temperatures systematically increase atmospheric evaporative demand, forcing already fragile landscapes toward severe aridity unless substantial steps are taken to curtail planet-warming pollution.

Beyond lowering emissions, researchers and land managers emphasize the necessity of proactive environmental restoration and conservation. Re-establishing native vegetation, pursuing targeted reforestation, minimizing soil erosion, and rehabilitating local watersheds serve as vital lines of defense against encroaching desertification.

Improving soil organic matter is regarded as a particularly effective resilience strategy. By adopting carbon farming techniques, agricultural producers can use healthy soil to store carbon while simultaneously enhancing its ability to retain moisture and crucial nutrients during prolonged dry spells.

With drylands exhibiting an exceptionally high ecological vulnerability, the study's authors underscored that continuously updated assessments of aridity distribution are critical. Accurate data will be essential to inform future climate adaptation frameworks and safeguard sustainable development before expanding arid zones permanently alter the planet's arable geography.