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Invertebrates and microorganisms living on or below the soil surface provide needed goods and services to human societies (e.g., mixing and aeration of soils, decomposition of materials and human waste) (Daily et al., 1997). These processes contribute to creation of fertile topsoil from organic matter and mineral components of the soil. Some of these organisms (e.g., ants) are susceptible to climatic changes, especially droughts (Folgarait, 1998). On a global scale, the estimated cost of replacing waste elimination services performed by these organisms is hundreds of billions of U.S. dollars annually; the estimated cost of replacing topsoil production services is tens of billions of U.S. dollars annually (de Groot, 1992; Crosson et al., 1995; Pimentel et al., 1995; Daily et al., 1997).
Another way of assessing the value of wildlife is by examining how much is spent on its conservation. In fiscal year 1995, approximately US$330 million was spent on the conservation of threatened and endangered species in the United States and its territories (U.S. Fish and Wildlife Service, 1995). As pressures facing wildlife increase, the number of species that require conservation attention also will most likely increase.
People in many parts of the world depend on wildlife for their daily nutritional needs. This is most pronounced in less-developed areas. For example, the Cree along James Bay in Canada harvest approximately 800,000 kg of animal food annually. The per capita replacement value of this harvest was estimated to be CDN$6,000 in 1986 dollars (Scott, 1987). The abundance of caribou (Rangifer tarandus groenlandicus) available for harvest by indigenous peoples could decrease as a result of increased temperatures, snowfall, and potential shifts in the timing of precipitation (Brotton and Wall, 1997; Ferguson, 1999). Adverse impacts also have been projected for other subsistence species, including marine birds, seals, polar bears (Stirling, 1997), tundra birds (Jefferies et al., 1992), and other tundra-grazing ungulates (Jeffries, et al., 1992; Gunn, 1995).
Wildlife species also are a significant source of food and medicine for people in many temperate and tropical countries, such as Botswana and Nigeria (McNeely et al., 1990) and Australia (Bomford and Caughley, 1996). Among the Boran (Kenya), birds are used for medicines (ostrich oils) and their feathers for cleaning wounds (Isack, 1987). In many countries, climate change impacts such as reductions in wildlife populations may have the greatest impact on the lowest-income groups—those with the least ability to adapt if hunting opportunities decline (Arntzen and Ringrose, 1996).
In many African countries, ecotourism to view wildlife is a major contributor to gross national product (GNP). Worldwide, ecotourism is estimated to provide US$500 billion to 1 trillion annually to the global economy (Munasinghe and McNeely, 1994). Changes in climate could reduce the populations of some of the species people are willing to pay to see (Mills et al., 1995; Allen-Diaz, 1996).
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