Aridity

Growing aridity poses threats to global land surface - Nature

: Extreme dryness with almost no vegetation; covers 4.2% of global land. aridity

: Limited rainfall and specialized vegetation; covers 14.6% of global land. Growing aridity poses threats to global land surface

: Transition zones with enough moisture for grass and some crops; covers 12.2% of global land. Drivers and Ecological Impact Drivers and Ecological Impact Regions are categorized based

Regions are categorized based on their AI values to determine the severity of water limitation. According to the Food and Agriculture Organization (FAO) , drylands cover roughly 41% of the Earth's land surface and are classified into three primary zones:

Aridity: Understanding the Long-Term State of Water Scarcity

Aridity is a permanent climatic feature of regions where the long-term average water supply (precipitation) is significantly lower than the atmospheric demand for water (potential evapotranspiration). Unlike drought, which is a temporary and anomalous period of moisture deficit, aridity is a chronic state of water scarcity that defines the very character of an ecosystem. It is primarily measured using the , calculated as the ratio of annual precipitation to potential evapotranspiration. Classification of Arid Environments