A couple walks home during a dust storm in Xinlinhot, China
Regional and Global Consequences of Desertification beyond Drylands
Desertification has environmental impacts at the global and regional scale. Affected areas may sometimes be located thousands of kilometers away from the desertified areas. Desertification-related processes such as reduction of vegetation cover, for instance, increase the formation of aerosols and dust. These, in turn, affect cloud formation and rainfall patterns, the global carbon cycle, and plant and animal biodiversity. For example, visibility in Beijing is often adversely affected by dust storms originating in the Gobi Desert in springtime. Large dust storms emanating from China affect the Korean peninsula and Japan and are observed to even have an impact on North American air quality.
An increase in desertification-related dust storms is widely considered to be a cause of ill health (fever, coughing, and sore eyes) during the dry season.Dust emanating from the East Asian region and the Sahara has also been implicated in respiratory problems as far away as North America and has affected coral reefs in the Caribbean. (Dust storms can also have positive impacts, however; for example, air-transported dust deposits from Africa are thought to improve soil quality in the Americas). Finally, reduction of vegetation cover in drylands leads to destructive ﬂoods downstream and excessive clay and silt loads in water reservoirs, wells, river deltas, river mouths, and coastal areas often located outside the drylands (C22.5.2, C14 Box 14.4, C12.2.4, R11.3.2, R11.1.3).
The societal and political impacts of desertification also extend to non-dryland areas. Droughts and loss of land productivity are predominant factors in movement of people from drylands to other areas, for example (medium certainty). An inﬂux of migrants may reduce the ability of the population to use ecosystem services in a sustainable way. Such migration may exacerbate urban sprawl and by competing for scarce natural resources bring about internal and cross-boundary social, ethnic, and political strife. Desertification-induced movement of people also has the potential of adversely affecting local, regional, and even global political and economic stability, which may encourage foreign intervention C22.ES, C22.1.3, C22.6.1, C22.6.2).