Scientists have warned that by the end of the 21st century, territories where evaporation significantly exceeds precipitation could cover more than 40% of the planet's land surface. Rising carbon dioxide concentrations may only partially slow this process. The study is published in Environmental Research Letters.

What Arid Lands Are and What the Forecast Says

Arid lands include deserts, semi‑deserts, and dry steppes. Life in such areas is particularly sensitive to water shortages and soil degradation, and their expansion threatens agriculture and water supplies for billions of people.

Researchers from the Chinese Academy of Forestry analysed climate data from 1994–2023 and constructed a forecast for the period 2071–2100. Currently, arid lands occupy about 38.58% of the land surface (excluding Antarctica). By the end of the century, their share is projected to rise to 39.31–40.28%.

In absolute terms, this means an increase of about 2.37 million square kilometres—an area comparable in size to Algeria. The most notable expansion of dry zones is expected in Australia.

Why the New Forecast Is More Moderate Than Previous Ones

Earlier estimates had suggested that arid lands could cover up to 56% of land. The new calculation is more cautious because the authors took into account the effect of rising CO₂ levels. Carbon dioxide enhances plant growth and helps plants use water more efficiently, partially counteracting desertification.

However, the overall trend remains alarming: the climate is becoming drier. The mitigating effect of rising CO₂ is not unlimited. As plants become saturated with carbon dioxide, its restraining influence will weaken, while warming will continue to dry out the land.

What This Threatens

The expansion of arid territories primarily hits agriculture. Cultivable areas shrink, crop yields fall, and pressure on water sources increases. Regions where dry zones already border populated and agricultural areas are particularly vulnerable.

The scientists emphasise that such changes must be prepared for in advance—by developing measures for soil protection and water conservation.

In Brief

According to the scientists' forecast, by 2100 arid lands could cover 39.3–40.3% of Earth's land surface—2.37 million square kilometres more than today. The changes will affect Australia the most. The new calculation is more moderate than earlier estimates because it accounts for the partial mitigating effect of rising CO₂ on desertification; however, the overall trend towards climate drying remains and threatens agriculture and water supplies.