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Chapter 8
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IntroductionOne of the most fundamental and serious environmental impacts is when a species of animal or plant disappears from a locality or, worse, is made extinct on the planet. Some of the first alarms from environmentalists in modern times dealt exactly with this threat. For example, Rachel Carson's now legendary book Silent Spring from 1962, describes how the birds living at a lake disappeared due to the fact, as it turned out, that the insects they fed on were killed by DDT and so the spring became a very silent one. The first widely noticed alarms of environmental impact on the Baltic Sea in the 1950s and later were also connected with disappearing species, as Grey seals and White-tailed eagles drastically diminished in numbers. Some of the earliest measures of environmental protection concerned threatened animals, e.g. the hunting of the Bengali tiger was outlawed already in the 1700s. This concern with species survival is well motivated. Biodiversity at the species level is in a way the ultimate indicator of environmental impact. The final loss, the extinction, of a species constitutes an irreversible loss of genetic potential, a loss of a natural resource and a final violation of bioethics. Man's onslaught against other species has a terrible history, which we need to understand to comprehend the contemporary situation. From earliest times man has either overused the resources provided by other species and thereby destroyed them forever, or simply changed their living environment so much that they could not continue to exist. All different kinds of environmental impacts influences the possibilities for other life forms to survive, multiply and flourish: spatial intrusion, reduced access to water, and of course chemical pollution, all limit the habitat of life forms. Environmental impacts may be accidental, but in fact manipulation of the biology of the planet is to a very large extent intentional and part of the development of human societies from the very beginning. Since plants and animals are what feed us, this is natural, but nature has been exploited in an unscrupulous way. From extinction of the megafauna hundreds or thousands of years ago, to the large scale animal production of today, the consequences have been immense. Today some 90% of terrestrial higher animal biomass represents animals that are produced and owned by man. Wild animals like moose, foxes and the like, have been left with very little space. Deliberate and accidental introductions of animals and plants have lead to unintentional spreading of invasive species. In some environments this has been very destructive, leading to a completely changed flora and fauna. Biodiversity studies tell us that the evolutionary period of a species the time from its appearance on Earth until its extinction is today about an order of magnitude shorter than normal. This means that we exist in one of the largest periods of extinction in the history of the planet, comparable for example to the situation 65 million years ago when the dinosaurs became extinct. The earlier six identified periods of mass extinction had cosmic causes. This time it is us humans that direct the ominous screen play. A series of measures have been undertaken to protect biodiversity. These include nature conservation and establishment of protected areas. Inventories of species in a "Red List" of different levels of survival status helps identify species that need protection. In the end, however, it seems that the most necessary change is the one that must take place in our minds. Respect for other species and a willingness to share the environment with them is a prerequisite for creating a world where other life forms are given a chance of continued existence. Authors of this chapter are: |
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