Drylands could cover more than half of the global land surface by 2100 if global emissions continue to rise, reports a paper published online in Nature Climate Change. The study suggests that this will have a disproportionate effect on developing countries, where over three-quarters of the dryland expansion is projected to occur, and could exacerbate poverty levels and land degradation.

Drylands are regions where precipitation is offset by evaporation from surfaces and plant leaves. They currently cover approximately 40% of global land surface and are expected to increase in size due to climate change and human activities, such as urbanization and population growth.

Jianping Huang and colleagues compare historical observational data (1948-2005) to global climate model simulation data and find that the climate models underestimate global drying trends. They then use the observational data to correct the model projections and investigate change in dryland coverage under moderate and high emissions scenarios. Under a high emissions scenario, the authors find the land surface area that drylands cover will increase by 23% by 2100 (compared to baseline dryland coverage from 1961-1990), with 56% of global land surface covered. They find that 78% of this expansion will occur in developing countries.

The authors observe greater warming trends over dryland regions than humid regions, and conclude that the combination of temperature and aridity increases with population growth in developing countries will amplify the risk of further dryland expansion.