Aridity

"Arid" and "Dry climate" redirect here. For an arid climate, see Desert climate. For the Belgian rock band, see Arid (band).

Arid regions of the Western United States as mapped in 1893

Aridity is the condition of geographical regions which make up approximately 43% of total global available land area, characterized by low annual precipitation, increased temperatures, and limited water availability [1][2][4][5].These areas tend to fall upon degraded soils, and their health and functioning are key necessities of regulating ecosystems’ atmospheric components [3][4].

Change over time

Main article: Aridification

The distribution of aridity at any time is largely the result of the general circulation of the atmosphere. The latter does change significantly over time through climate change. For example, temperature increase by 1.5–2.1 percent across the Nile Basin over the next 30–40 years could change the region from semi-arid to arid, significantly reducing the land usable for agriculture. In addition, changes in land use can increase demands on soil water and thereby increase aridity.^[1]

A December 2024 report from the UNCCD concluded that more than three-quarters of the Earth's land "has become permanently dryer in recent decades", that "drier climates now affecting vast regions across the globe will not return to how they were", and that a quarter of the global population lives in expanding drylands.^[2]

See also

• Arid Forest Research Institute
• Aridity index
• Desiccation tolerance
• Drought
• Humidity
• Vapor pressure

References

1. Dunkerley, David, (2020),The Ecohydrology of Desert Environments: What Makes it Distinctive?, Encyclopedia of the World's Biomes, Elsevier, Pages 23-35, ISBN 9780128160978, https://doi.org/10.1016/B978-0-12-409548-9.11803-22.
2. FAO. Elaboración de un Programa Mundial Sobre Agricultura Sostenible en Zonas Áridas en Colaboración con el Marco Mundial Sobre la Escasez de Agua en la Agricultura en un Clima Cambiante. http://www.fao.org/3/nd412es/nd412es.pdf
3. FAO. Secuestro de Carbono en Tierras Áridas. http://www.fao.org/3/Y5738s/Y5738s.pdf
4. Perez-Aguilar, L. Y., Plata-Rocha, W., Monjardin-Armenta, S. A., Franco-Ochoa, C., & Zambrano-Medina, Y. G. (2021). The Identification and Classification of Arid Zones through Multicriteria Evaluation and Geographic Information Systems—Case Study: Arid Regions of Northwest Mexico. ISPRS International Journal of Geo-Information, 10(11), 720. https://doi.org/10.3390/ijgi10110720
5. Quichimbo, E.A.; Singer, M.B.; Cuthbert, M.O. Characterising Groundwater-Surface Water Interactions in Idealised Ephemeral Stream Systems. Hydrol. Process. 2020, 34, 3792–3806.  https://doi.org/10.1002/hyp.13847

1. United States Geological Survey (24 May 2017). "Increasing Aridity and Land-use Overlap Have Potential to Cause Social and Economic Conflict in Dryland Areas". Retrieved 29 July 2022.
2. "The Global Threat of Drying Lands: Regional and global aridity trends and future projections" (PDF). United Nations Convention to Combat Desertification (UNCCD). 9 December 2024. p. 7 (Forward). Archived (PDF) from the original on 10 December 2024.

• Griffiths, J. F. (1985) 'Climatology', Chapter 2 in Handbook of Applied Meteorology, Edited by David D. Houghton, John Wiley and Sons, ISBN 0-471-08404-2.
• Durrenberger, R. W. (1987) 'Arid Climates', article in The Encyclopedia of Climatology, p. 92–101, Edited by J. E. Oliver and R. W. Fairbridge, Van Nostrand Reinhold Company, New York, ISBN 0-87933-009-0.
• Stadler, S. J (1987) 'Aridity Indexes', article in The Encyclopedia of Climatology, p. 102–107, Edited by J. E. Oliver and R. W. Fairbridge, Van Nostrand Reinhold Company, New York, ISBN 0-87933-009-0.
• Blue Peace for the Nile Report, 2009, Strategic Foresight Group