By around 2100, 40% of land areas will consist of arid zones

By the end of the 21st century, approximately 40% of the emerged land will be composed of arid areas. This was revealed by a new study published in the scientific journal Environmental Research Letters.

The research

By mapping the current global distribution of drylands, the study quantifies historical and future changes in dryland extent and identifies dryness and moisture tipping points under different emissions scenarios. Using the period 1994-2023 as a reference, global drylands currently occupy approximately 38.58% of the global land surface. From 1960 to 2023, dryland extent showed a fluctuating but overall increasing trend. Future projections indicate continued but slower expansion over the 21st century than the historical trend. By the end of the 21st century, drylands are expected to cover approximately 40.28% of the global land surface.

Global climate conditions have changed substantially over the last decade. Recent drought intensification and land-atmosphere feedbacks suggest that some regions may have already shifted towards drier conditions. Because dryland boundaries are defined by the aridity index (AI), which integrates precipitation and potential evapotranspiration (PET), changes in water supply or atmospheric evaporative demand can alter the spatial extent of drylands. Therefore, the current spatial distribution of global drylands needs to be reassessed using updated climate data.

In this study, aridity change hotspots are defined as regions where the aridity index (AI) changes significantly. Dryness hotspots are identified by significant declines in AI, while humidification hotspots are identified by significant increases in AI. Future dryland projections are sensitive to the representation of potential evapotranspiration (PET).

CO2 emissions

CO2-related physiological effects remain an important source of uncertainty in future projections of dry-wet periods, but their implications for global dryland redistribution and tipping points of aridity change remain insufficiently assessed. To fill this gap, the study evaluates future global redistribution of arid areas and tipping points of aridity change using a modified CO2 model.

The main objective of this study is to quantify the current and future distribution of arid areas globally and identify dryness and moisture hotspots under different emissions scenarios.