Desert, global area

We will consider both Steppe and Desert ecosystems as deficient in atmospheric humidity (evapotranspiration exceeds precipitation). The Sub-Boreal, Semi-arid and Arid Steppe and Desert ecosystems occupy a significant part of the global area. This territory includes Sub-Boreal zones (Steppe, Arid Steppe, and Desert Steppe ecosystems) with total area of 9.23 x 10 km, as well as subtropical zones (Shrub Steppe and Desert Steppe ecosystems) with total area of 7.04 x 10 km. These areas do not include Subtropical and Tropical Sandy Desert ecosystems (5.77 x 10 km-) and Stony Desert ecosystems (8.96 x 10 km ). Thus the extra-tropical arid area takes about 20% of the World s terrestrial ecosystems. Most of this area goes to the inter-continental regions of Eurasia and, partly, of North and South America. The biogeochemistry of semi-arid and arid ecosystems shows distinctive parameters, which allow us to consider the quantitative features of element turnover and dynamics in natural fluxes. 

Fig. 7-6 Satellite observations of global reflectivity for January 1967-1970. White indicates areas of persistent cloudiness and relatively high precipitation, except for northern Africa where desert surface regions are highly reflective. (From US Air Force and US Department of Commerce (1971). "Global Atlas of Relative Cloud Cover," 1967-1970, Washington.)...

Figure 6.1. Ecosystem area and soil carbon content to 3-m depth. Lower Panel Global areal extent of major ecosystems, transformed by land use in yellow, untransformed in purple. Data from Hassan et al. (2005) except for Mediterranean-climate ecosystems transformation impact is from Myers et al. (2000) and ocean surface area is from Hassan et al. (2005). Upper Panel Total C stores in plant biomass, soil, yedoma/permafrost. D, deserts G S(tr), tropical grasslands and savannas G(te), temperate grasslands ME, Mediterranean ecosystems F(tr), tropical forests F(te), temperate forests F(b), boreal forests T, tundra FW, freshwater lakes and wetlands C, croplands O, oceans. Data are from Sabine et al. (2004), except C content of yedoma permafrost and permafrost (hght blue columns, left and right, respectively Zimov et al., 2006), and ocean organic C content (dissolved plus particulate organic Denman et al., 2007). This figure considers soil C to 3-m depth (Jobbagy and Jackson, 2000). Approximate carbon content of the atmosphere is indicated by the dotted lines for last glacial maximum (LGM), pre-industrial (P-IND) and current (about 2000). Reprinted from Fischlin et al. (2007) in IPCC (2007). See color insert.

Overall, we will need to harvest nearly three times as much farm output in 2050 as we harvest today - and we re already farming half the global land area not under deserts or glaciers. Pest control will remain vital to both people and wildlife. 

Boron is present in the earth s crust at a level of only three parts per million, but there are areas where it is concentrated as borate salts (salts of the oxidized form of elemental boron) in substantial volumes for mining. The United States and Turkey supply 90% of the global borate demand. Rio Tinto Minerals (RTM)/U.S. Borax, the largest borate producer, operates an open pit mine and refinery complex in the Mojave desert of California. The principal minerals in the deposit are tincal and kernite (Table 9.1). 

In contrast to classical targets, in the on-going global war on terror (GWT), new targets such as tunnels, caves and remote desert or mountain areas have become important. 

The trend is simply shown in Fig. 5, which takes a global difference of the GVI in July between 1990 and 86. This period is continuous temperature rise as shown in Fig. 3. Then the differences are counted over the value of 110 GVI, that is, excluded desert or soil regions. Increased areas are... 

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