There are no precise estimates of the sizes of any deserts and some land that is clearly desert may have been omitted from this compilation. Nevertheless, it serves as a starting point for determining which land can be used to serve the purposes of global surface albedo enhancement.

 

Not all desert land is uninhabited (2), unproductive (3), devoid of vegetation (4), and completely flat and stable (8). So the next step is to identify those desert lands that most completely satisfy all 8 criteria. To obtain precise estimates will require an effort substantially beyond the scope of this research plan and the services of physical geographers, among others. However, some crude estimates can be made.

 

Although several hundred million people live within the boundaries of the desert areas identified, most of the population is concentrated in and around a few cities (115). The vast majority of the territory is unoccupied. Likewise, with the exception of oil wells in the Sahara and Arabian deserts, the land is generally considered useless, except for tourism.

 

Regarding topography, most desert land is not composed entirely of sand dunes and cactus plants as is typically represented in the popular culture, but consists of a combination of gravel plains, dry lakebeds, scrub vegetation, sand dunes and mountains. The gravel plains and dry lakebeds are the most desirable for this project because they appear to meet all 8 criteria.

 

As examples of this diversity, the Sahara is only 15-30% sand and 70-85% rocks and gravel plains (114, 116), whereas much of the Kalahari is sand dunes and the Chihuahuan is mostly shrub vegetation. The Sonoran is also well vegetated due to the relatively high rainfall it receives.

 

We rank the deserts in order of their suitability for albedo enhancement as follows:

 

Category 1 (significant gravel plains)

Sahara

Arabian

Namib

Mojave

Atacama

Patagonian

Kara-Kum

Kyzyl-Kum

Iranian

Taklamakan

Gobi

Thar

 

6.0 million sq. mi.

 

Category 2 (too highly vegetated or sandy)

Sonoran, Chihuahuan,

Australian, Kalahari

 

1.1 million sq. mi.

 

Category 3 (too mountainous)

Great Basin, Colorado Plateau

 

320,000 sq. mi.

 

As a first estimate, we believe that around 75% of the 6.0 million square miles of desert area in the first category or 4.5 million square miles could eventually be considered suitable for this project. Again, these estimates are crude and require refinement. These estimates also do not address the surface albedos or annual average incident solar radiation. It is noted that while the two largest, the Sahara and Arabian, are both subtropical, some of the others, including the Gobi, Patagonian and Taklamakan lie at much higher latitudes and as a consequence, will not receive the same amount of sunlight. Thus, their potential for albedo enhancement per square mile is expected to be less.