Wilderness - Extent

Extent

According to a major study, Wilderness: Earth's Last Wild Places, carried out by Conservation International, 46% of the world's land mass is wilderness. For purposes of this report, "wilderness" was defined as an area that "has 70% or more of its original vegetation intact, covers at least 10,000 square kilometers (3,900 sq mi) and must have fewer than five people per square kilometer." However, an IUCN/UNEP report published in 2003, found that only 10.9% of the world's land mass is currently a Category 1 Protected Area, that is, either a strict nature reserve (5.5%) or protected wilderness (5.4%). Such areas remain relatively untouched by humans. Of course, there are large tracts of lands in National Parks and other protected areas that would also qualify as wilderness. However, many protected areas have some degree of human modification or activity, so a definitive estimate of true wilderness is difficult.

The Wildlife Conservation Society generated a human footprint using a number of indicators, the absence of which indicate wildness: human population density, human access via roads and rivers, human infrastructure for agriculture and settlements and the presence of industrial power (lights visible from space). The society estimates that 26% of the Earth's land mass falls into the category of "Last of the wild." The wildest regions of the world include the tundra, the taiga, the Amazonian rain forest, the Tibetan Plateau, the Australian outback and deserts such as the Sahara, and the Gobi. However from the 1970s, numerous geoglyphs have been discovered on deforested land in the Amazon rainforest, leading to claims about Pre-Columbian civilizations. The BBC's Unnatural Histories claimed that the Amazon rainforest, rather than being a pristine wilderness, has been shaped by man for at least 11,000 years through practices such as forest gardening and terra preta.

It should be noted that the percentage of land area designated "wilderness" does not reflect "quality" of remaining wilderness, part of which is barren areas with low biodiversity. Of the last natural wilderness areas, the taiga—which is mostly wilderness—represents 11% of the total land mass in the Northern Hemisphere. Tropical rainforest represent a further 7% of the world's land base. Estimates of the Earth's remaining wilderness underscore the rate at which these lands are being developed, with dramatic declines in biodiversity as a consequence.