Scientific Evidence and Economic Consequences

Biological diversity refers to the variety of living organisms on earth, the range of species, the genetic variability within each species, and the varied characteristics of ecosystems. Today, loss of species and their habitats is a problem of global dimensions; it potentially undermines the equilibrium supporting ecological security. Well over 1,000 species per year may be disappearing, compared to only 1-4 species per year from the fossil record.14

It is difficult to understand exactly what impact human activities have on biodiversity, because the total number of species in the world is unknown.

However, a recent study estimates the total number of existing species as about 13 million, of which less than 2 million have been described.15 Most intensely studied are plants and chordates (fish, birds, mammals). Studies estimate that the impact of human activities on other species has threatened the continued existence of 18 percent of mammals, 11 percent of birds, 8 percent of plants, and 5 percent of fish.16

Deforestation is a primary cause of biodiversity loss, as forests are home to more than one-half of all species. Population growth and the timber industry are the primary factors causing a substantial reduction in the world's forests.17 Biodiversity loss has enormous consequences for humans. In economic terms alone, global threats to species and ecosystems may cost at least $33 trillion.18 The increasing loss of species threatens purification of air and water, food security, and complex compounds used in medicines, among other adverse consequences. Significantly for developing countries, however, the economic costs of biodiversity loss can be diffuse and are not always felt immediately; while reaping the benefits of biodiversity conservation can require trade-offs with the more immediate and economic benefits of development.

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