Biodiversity Impacts: Loss of Species and Ecosystems
Studies of the potential impacts of global warming have largely focused on the physical and human impacts, such as sea level
rise, effects on agriculture, losses in timber resources, and impacts on human health. More recently, however, studies have
begun to look at the effects on environmental concerns, such as the loss of species and biological diversity (Markham, et.al.,
1993, p. 12).
Rising temperatures, the proliferation of disease, loss of habitat through storms, floods, and fires, and other impacts of global
warming threaten numerous species of plants and animals. Most species cannot tolerate rapidly changing habitat conditions.
Many are therefore likely to become extinct (Peters and Lovejoy, 1992, p. 7).
As with forests and impacts on human health, it is impossible to identify the total value of lost species in terms of dollars.
Species and ecosystems are valuable "for their own sake." Therefore, any attempt to assign a monetary value to them will
underestimate their true worth. Nevertheless, identifying at least part of the value of species in monetary terms provides a useful
illustration of the importance of biodiversity to society — and raises the awareness that such resources are not "free."
Take, for example, the ecological — and economic — importance of coral reefs. Reefs not only provide habitat for thousands
of species of plants and animals (including a third of all fish species), but they are also a significant resource for tourism, fishing,
medical research, and other benefits (Corson, 1990, p. 137). In the Caribbean, marine-based tourism generates billions of
dollars through transportation, food, lodging, services, and local purchases. In 1988, Caribbean tourism was estimated to
generate more than $8.5 billion, of which divers and other special-interest tourists accounted for up to one-fifth (Dixon and
Sherman, 1990, p. 179). In addition, healthy reefs protect shorelines from erosion by acting as self-repairing breakwaters.
They therefore help reduce the need for expenditures on beach protection or replenishment.
Evidence is mounting, however, that the world's coral reefs, already severely threatened by dredging, coral-collecting,
dynamite fishing, and other destructive activities, face increasing danger of coral "bleaching" from warming tropical waters. The
EPA reports that warmer than usual temperatures in tropical waters have already been implicated in the increased incidence
and severity of coral bleaching and death worldwide (U.S. EPA, 1989, p. 143). Communities that depend on coral reefs for
tourism, fishing, and other uses stand to lose billions of dollars a year.
Other forms of wildlife provide similar economic benefits. In 1985, over 109 million people participated in wildlife-related
recreation, including bird-watching and feeding, and wildlife photography (U.S. Fish and Wildlife Service, 1988). People spent
$4.5 billion on equipment and generated $17.9 billion through their activities (Gray, 1993, p. 98). The loss of such wildlife and
habitat would harm both the economy and people's ability to enjoy nature.
Global warming could also cost society lost opportunities for using certain species for medicines and other purposes in the
future. Over 40 percent of the prescription drugs sold in the U.S. contain chemicals originally derived from wild species
(Corson, 1990, p. 103). The economic value of plant-based drugs provides at least a hint of the value of biodiversity to
society. In the U.S., the market value of prescription and over-the-counter drugs in 1985 was estimated at $19.8 billion
($1990) (Pearce, 1993, p. 86). Worldwide, they totaled to over $84 billion. If species die off due to the impacts of
human-induced climate change, we limit the opportunities of coming generations to discover important new medicines.
It is important to recognize that these figures represent merely the "tip of the iceberg" of the consequences of global warming
on species and ecosystems. Economic values do not capture the important role that every species plays in the Earth's
ecological systems; nor do they reflect the fact that once a species is extinct, it is gone forever.
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