One of the great dangers facing those who attempt to prophesy is that estimates, coming from the best of intentions, may become more catastrophic than the data warrant. Extinction is an emotional issue for many of us, even (or especially) scientists, and emotion can color judgment and distort objectivity. There is a very real possibility that estimates of current extinction rates are inflated. Few studies are able to pinpoint how real the threat of elevated extinction rates really is, or how prolonged it will be. There is a tendency by some working in this field to cry doom when a much more muted response may be justified.
It is clear that the planet is in a period of elevated extinction rates. But just how elevated, compared with the period prior to the population run-up of our own species, is the most pressing question, and one that is very difficult to answer. There is a possibility that most of the consequential extinction (i.e., among the megamammals) has already occurred, and that little further reduction in the Earth's biota will accumulate over the next few centuries or millennia. Thus it may be that the estimation of losses through mass extinction is wildly overstated.
Following are several reasons why the current mass extinction may be less severe than many estimates predict:
1. Most species are resilient—more resilient than previously thought
For all of the extinctions currently thought to be under way, actual case histories of extinctions are rather few. Those species that have gone extinct, ranging from the dodo to the passenger pigeon, may be species that for any number of reasons were extremely susceptible to extinction to begin with. Extinction requires the death of every living individual of a given species. All species are the result of a long period of evolution. They do not just go away; something must eventually kill them all off, and that cause must be sufficient to end a history in most cases counted in millions of years.
2. Conservation efforts will be more successful than previously thought
Worldwide conservation efforts have brought to light the plight of many endangered species. Virtually every country on Earth now practices some form of conservation, be it by preserving large national parks or by protecting individual species or given habitats. These efforts have occurred only in the last two to three decades on a worldwide basis. Yet they have already registered a number of remarkable successes, notably in the restoration of whale and large bird species. Bans on dangerous chemicals such as DDT have vastly aided this process. These efforts alone may be sufficient to reverse the course of the oncoming and ongoing mass extinction.
As we have seen, one of the most maddening aspects of biodiversity studies is our very poor knowledge of the most basic baseline figure, the actual number of species on Earth, and the corollary to that figure, the reduction of species numbers among various taxonomic groups and specific habitats. In very few other avenues of science are the error ranges quite so great: an order of magnitude separates the high and low figures. It may be that there are a very large number of species on Earth, and that a relatively low percentage of them have recently undergone extinction, or will do so in the near future.
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