Aridification

Aridification is the long-term process by which a region experiences a net reduction in moisture availability, leading to persistently drier conditions and lower ecosystem and agricultural productivity. It describes broad shifts in climate and water balance, and it is distinct from short-term drought, though drought events can contribute to or reveal aridification trends.

Causes and mechanisms include rising temperatures that increase atmospheric and soil evaporation, alterations in precipitation patterns and amounts, and intensification of evaporation in many landscapes. Human activities such as over-extraction of groundwater, excessive irrigation, deforestation, and land degradation can degrade soil structure and reduce its capacity to retain moisture. These factors can interact with natural climate variability to produce gradual, long-lasting drying in a region.

Aridification is monitored through aridity indices, such as the ratio of precipitation to potential evapotranspiration, along with indicators like soil moisture, groundwater levels, and drought indices derived from precipitation and temperature records. It has been observed or projected in various regions, including parts of the Mediterranean, southern Africa, the southwestern United States, Central Asia, and parts of Australia, where climatic and hydrological changes increasingly reduce moisture availability.

Impacts include water scarcity for drinking and farming, declines in crop yields and livestock productivity, shifts in natural ecosystems and biodiversity, and increased risk of wildfires and dust events. Adaptation and mitigation efforts emphasize water conservation and efficiency, drought-tolerant crops, improved irrigation and groundwater management, rainwater harvesting, land restoration, and cross-sector planning to build resilience against ongoing dryness.