On the First Meeting of the Conference of the Parties to the Convention on Biological Diversity, Nassau, The Bahamas, 28 November - 9 December 1994Dr. Peter Raven, Director of the Missouri Botanical Gardens. The feature originally appeared in "Our Planet," Vol. 6, No.4, 1994.
We are confronting an episode of species extinction greater than anything the world has experienced for the past 65 million years. Of all the global problems that confront us, this is the one that is moving the most rapidly and the one that will have the most serious consequences. And, unlike other global ecological problems, it is completely irreversible.
The Earth, our planetary home, is truly finite. Economic formulas, developed over the past 200 years to keep track of the values involved in human transactions, cannot make it any larger. Nor can they give us any more of the productive systems and commodities on which we depend. No matter how clever we may be, the Earth remains the same. We can use it and its systems sustainably, or we will destroy them.
Our species first appeared about 500,000 years ago, at the very last instant, as it were, of the planet's 4.5 billion-year history. As our hunter-gatherer ancestors began to move over the face of the Earth, they also began to exterminate many of the large animals and birds that they killed for food. When agriculture was invented - independently in eastern Asia, the eastern Mediterranean, Mexico, and Peru - 11,000 to 8,000 years ago, there were perhaps as few as 5 million people throughout the world. But this population then began to grow quickly, and the extensive land clearing and grazing that characterized early agriculture caused rapidly increasing extinctions.
The number of people grew steadily to an estimated 130 million 2,000 years ago, 500 million by 1650, 2.5 billion by 1950, and a rapidly growing 5.5 billion today. Over the last 40 years, we have wasted about a fifth of the world's topsoil; lost about an eighth of our cultivated lands to desertification, waterlogging, and salinization; increased greenhouse gasses in the atmosphere by over a third, setting the world on an inexorable course to warmer climates; destroyed more than 5 per cent of the stratospheric ozone layer; and cut - or converted to simplified biological deserts - about a third of the forests that existed in 1950.
Super ConsumersHuman beings - just one of an estimated 10 million species on the planet - are currently estimated to be consuming, wasting, or diverting 40 percent of the net photosynthetic production on land. We are using an estimated third of the planet's available fresh water. And yet our numbers are not likely to stabilize until they have reached two or three times their present level, even with continued worldwide attention to family planning, because there is such a high proportion of young people in developing countries.
Already our impact on forests and other biologically rich communities is so intense around the world that we are losing species at between 1,000 and 10,000 times the natural rate that occurred before our ancestors first appeared on Earth. Judged from the fossil record, the average life span of a species is about 4 million years, so if there are about 10 million species in the world, the background rate of extinction can be calculated at about four species a year. At a moderate estimate, we are now likely to lose around 50,000 species a year over the next decades. The rate will presumably accelerate as the years go by. As E.O. Wilson has pointed out: clearly we are in the midst of one of the great extinction spasms of geological history.
If, as is possible, we lose two-thirds of all living species over the course of the next century, this will be more or less equivalent to the proportion which disappeared at the end of the Cretaceous period, 65 million years ago - one of the several great extinction events of Earth history. It took more than 5 million years for the world to regain its equilibrium after that. This is a sobering period of time to contemplate, not least because it is more than five times as long as the history of our own species.
Why does it matter? There are three classes of reason for concern. The first is ethical and aesthetic. As Paul Ehrlich and Ed Wilson put it in 1990, "because Homo sapiens is the dominant species on Earth, we and many others think that people have an absolute moral responsibility to protect what are our only known living companions in the universe. Human responsibility in this respect is deep, beyond measure, beyond conventional science for the moment, but urgent nonetheless."
The second class of reason is economic. We use organisms for food, medicines, chemicals, fiber, clothing, structural materials, energy, and many other purposes. Only about 100 kinds of plants provide the great majority of the world's food; they are precious and their genetic diversity should be preserved and enhanced. There are also tens of thousands of other plants, especially in the tropics, that have edible parts and might be used more extensively for food, and perhaps brought into cultivation, if we knew them better. But overconcentration on the 20 or so best known food plants tends to lead us to neglect the others.
Plants and other organisms are natural biochemical factories. More than 60 percent of the world's people depend directly on plants for their medicines: the Chinese use more than 5,000 of the estimated 30,000 species of plants in their country for medicinal purposes. Moreover, the great majority of Western medicines owe their existence to research on the natural products that organisms produce: for example, natural products played a role in the derivation of each of the top 20 pharmaceutical products sold in the United States in 1988. Relatively few of the 250,000 kinds of plants in the world have been fully examined, so it stands to reason that the remaining species contain many unknown compounds of probable therapeutic importance.
Gordon Cragg, chief of the Natural Products Branch of the National Cancer Institute, says: "No chemists can dream up the complex bioactive molecules produced by nature, but once the natural lead compounds have been discovered, then the chemists can proceed with synthetic modifications to improve on the natural lead."
For example, artemesin is the only drug effective against all of the strains of the Plasmodium organisms that cause malaria, which afflicts 250 million people a year. Its chemical structure is totally different from quinine and the other chemicals used against the disease over the past two centuries. Neither its existence, nor its effectiveness against malaria, could have been predicted had the Chinese not traditionally been using an extract of natural wormwood, Artemisia annua, to treat it.
Taxol, the only drug that shows promise against breast cancer and ovarian cancer, was initially found in the western yew by a United States Government program randomly screening plants for anti-cancer activities. Its molecule is structurally unique, and there is no way it could have been visualized if it had not been discovered in nature.
Following Nature's LeadA novel compound from the African vine Ancistrocladus korupensis, Michellamine B, shows a remarkable range of anti-HIV activity. It does not work in the same way as AZT and other anti-HIV drugs and, when its method of action is understood, may well assist in the discovery of other drugs that will be effective against AIDS.
Against this background, it is easy to understand why the major pharmaceutical firms are expanding their programs of exploration for new, naturally occurring molecules with useful properties. What is almost impossible to understand is why the world's nations have not already united in a major effort to explore and conserve the biodiversity on which so much of our common future will so clearly depend.
The third class of reason for being concerned about the loss of biodiversity centers on the array of essential services provided by natural ecosystems - including the protection of watersheds, the regulation of local climates, the maintenance of atmospheric quality, absorption of pollution, and the generation and maintenance of soils. Ecosystems, functioning properly, are responsible for the Earth's ability to capture energy from the sun and transform it into chemical bonds to provide the energy necessary for the life processes of all species, including ourselves.
Clearly, much of the quality of ecosystem services will be lost if the present episode of extinction is allowed to run unbridled for much longer. And the rebuilding of these systems, in which our descendants will necessarily be engaged, is likely to be seriously impaired by our neglect.
Global Stability NeededThe preservation of biodiversity can only be accomplished as part of an overall strategy to promote global stability. The first prerequisite of a sustainable world is the attainment of a stable human population. But this will not in itself allow the attainment of a stable world: for this, the problems of poverty and social justice must be addressed much more effectively throughout the world. More than four-fifths of the world's resources are consumed by the rapidly shrinking fraction of the global population (now less than a quarter of the total) that lives in industrialized countries; this overconsumption must be brought under control.
Assuming that the twin problems of population and poverty in the developing world and overconsumption in industrialized nations could be addressed adequately, there are a number of strategies that could be employed for the management of biodiversity, including the conservation of a reasonable sample of the species that exist today.
A worldwide system of protected areas, perhaps based at least in part on the UNESCO Biosphere Reserve and Man and the Biosphere (MAB) Reserve Programmes, ought to be established and maintained. They should be selected systematically so as to include the greatest possible proportion of the existing global biodiversity. They must be managed in a regional context, taking into account modified and partly natural ecosystems and human interactions of all kinds, since it will clearly not be possible to protect all of the world's biodiversity by preserving samples of pristine ecosystems permanently in their original condition. This will happen only with the full participation of the peoples of developing countries, who must be assisted strongly by the industrialized world, which must provide the bulk of the financial resources. The Global Environment Facility offers a model of how the funding for such programs might be organized.
Strengthen ScientistsMechanisms must be established for the preservation of samples of selected organisms outside these natural areas. Plants are one likely target: botanical gardens should be encouraged to form an operational network to conserve plants throughout the world, and a worldwide network of seed banks should also be formed. Other economically important groups of organisms, such as bacteria and fungi, lend themselves to preservation in culture centers.
Developing countries contain at least four-fifths of global biodiversity - and more than three-quarters of the world's population - but are home to only about 6 per cent of the world's scientists and engineers. The development of strong scientific communities in these countries is of fundamental significance. Their infrastructure must be strengthened as rapidly as possible with, among other factors, funds to acquire adequate library resources, the encouragement of direct collaboration between scientists in adjacent countries that share particular biomes, the provision of adequate computer facilities, and access to inexpensive and rapid communication.
One of the best strategies for strengthening the relative capabilities in developing countries is the development of national schemes for the management (including the preservation) of biodiversity. The Instituto Nacional de Biodiversidad (INBio) in Costa Rica provides one attractive model. National biological inventories are effective tools for national development, and can assist greatly in building national capabilities to deal with biological diversity.
Use and LearnAll nations should have access to the relevant biotechnology. Its intelligent use - helping to make possible the incorporation of biodiversity into everyday living and thus the stimulation of economic growth - leads directly to reduced pressures on natural ecosystems. Young scientists in the developing world should be encouraged to master the principles of biotechnology and to apply them to indigenous organisms. By applying these principles, hundreds of additional tropical species could be used appropriately at a commercial level. The knowledge possessed by indigenous peoples, and other rural peoples, must be viewed as a precious and rapidly vanishing field of information about which we must learn while there is still time.
Steps ought to be taken, for both scientific and economic reasons, to try to sample the diversity that exists now, because the next few decades can only be a time of catastrophic extinction. In many ways, we now have an opportunity comparable to that of living in the final decades of the Cretaceous period 65 million years ago. We have opportunities to sample the full range of biodiversity with which we coexist that will never occur again
