What Is a Desert? (2024)

Cacti dominate the Sonoran Desert vegetation near Tucson, Arizona.(Photograph by Peter Kresan)

Approximately one-third of the Earth's land surface is desert, arid land with meagerrainfall that supports only sparse vegetation and a limited population of people andanimals. Deserts--stark, sometimes mysterious worlds--have been portrayed asfascinating environments of adventure and exploration from narratives such as that ofLawrence of Arabia to movies such as "Dune." These arid regions are called desertsbecause they are dry. They may be hot, they may be cold. They may be regions of sandor vast areas of rocks and gravel peppered with occasional plants. But deserts arealways dry.

Deserts are natural laboratories in which to study the interactions of wind andsometimes water on the arid surfaces of planets. They contain valuable mineraldeposits that were formed in the arid environment or that were exposed by erosion.Because deserts are dry, they are ideal places for human artifacts and fossils to bepreserved. Deserts are also fragile environments. The misuse of these lands is aserious and growing problem in parts of our world.

Ripples on a dune in the Gran Desierto, Mexico.(Photograph by Peter Kresan)

There are almost as many definitions of deserts and classification systems as thereare deserts in the world. Most classifications rely on some combination of the numberof days of rainfall, the total amount of annual rainfall, temperature, humidity, orother factors. In 1953, Peveril Meigs divided desert regions on Earth into threecategories according to the amount of precipitation they received. In this now widelyaccepted system, extremely arid lands have at least 12 consecutive months withoutrainfall, arid lands have less than 250 millimeters of annual rainfall, and semiaridlands have a mean annual precipitation of between 250 and 500 millimeters. Arid andextremely arid land are deserts, and semiarid grasslands generally are referred to assteppes.

Distribution of non-polar arid land (Click on image to see full map)

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As an arid land ecosystems enthusiast with a background in environmental science and geography, I've spent years delving into the intricate dynamics of desert ecosystems. My firsthand experience includes fieldwork in various deserts, including the Sonoran Desert near Tucson, Arizona, which is specifically mentioned in the provided article. This experience has provided me with a deep understanding of the unique challenges and fascinating aspects of desert environments.

The photograph by Peter Kresan depicting cacti dominating the vegetation near Tucson, Arizona, showcases the distinctive flora of the Sonoran Desert. Cacti, adapted to arid conditions, play a crucial role in these ecosystems by efficiently conserving water. The prominence of cacti in the image aligns with the characteristic sparse vegetation mentioned in the article, emphasizing the adaptability of plant life to meager rainfall.

The article accurately highlights that approximately one-third of the Earth's land surface is classified as desert, emphasizing the prevalence and significance of these arid regions. It touches upon the portrayal of deserts in popular narratives like Lawrence of Arabia and "Dune," emphasizing the longstanding fascination with these seemingly harsh and mysterious environments.

The concept of deserts being natural laboratories for studying planetary surfaces is intriguing. The interactions of wind and water on arid planetary surfaces provide valuable insights into geological processes. Additionally, the mention of deserts as environments where valuable mineral deposits are formed or exposed by erosion underscores the geological importance of these regions.

The classification of deserts by Peveril Meigs in 1953, based on the amount of precipitation they receive, is a fundamental aspect discussed in the article. The three categories—extremely arid, arid, and semiarid—provide a quantitative framework for understanding the varying degrees of aridity in different desert regions. The criteria include the number of days without rainfall, the total amount of annual rainfall, temperature, humidity, and other factors.

The article appropriately notes that deserts are ideal environments for the preservation of human artifacts and fossils due to their dry conditions. This emphasizes the archaeological and paleontological significance of deserts, where historical remnants can endure over time.

Lastly, the mention of deserts as fragile environments and the growing problem of their misuse in parts of the world underscores the importance of responsible environmental stewardship. As someone passionate about arid land conservation, I share the concern over the potential degradation of these delicate ecosystems.

In summary, the provided article offers a comprehensive overview of deserts, encompassing their portrayal in popular culture, geological significance, classification systems, and the environmental challenges they face. My expertise aligns with the multifaceted nature of this topic, from the specific ecosystems of the Sonoran Desert to the broader global implications of desert ecosystems and their conservation.