The human species, 6.7 billion individuals strong, has modified its environment to such a degree that it is now hurting the biodiversity of terrestrial and marine species and, ultimately, its own survival. This to the point that an ever-growing number of scientists unhesitatingly talk about a sixth extinction, successor to the five others - all due to important natural modifications of the environment - that have punctuated life on Earth. The International Union for Conservation of Nature (IUCN), which focuses on over 41,415 species (of the roughly 1.75 million known) to establish its annual red list, estimates that 16,306 are threatened. One mammal species out of four, one bird species out of eight, a third of all amphibians and 70 percent of all plants assessed are in danger, the IUCN observes.
Is it still possible to curb this species decline, which is likely to intensify when our planet carries 9.3 billion humans in 2050? American biologists Paul Ehrlich and Robert Pringle (Stanford University, California) think so, as long as several radical measures are undertaken at a global level. They present these in the August 12 Proceedings in the National Academy of Sciences (PNAS) which devotes a special section to the sixth extinction. In their preamble, the two researchers declare outright that, "The fate of biodiversity for next ten million years will almost certainly be determined in the next fifty to one hundred years by the activity of a single species. That species, Homo sapiens, is about 200,000 years old." If one considers that mammalian species - of which we are one - last a million years on average, that places Homo sapiens in the middle of adolescence. Now we, this "spoiled teenager," "narcissistic and presupposing our own immortality, (...) mistreat the ecosystems that produced us and support us, mindless of the consequences," Paul Ehrlich and Robert Pringle add severely.
Consequently, according to the authors, we must instill a profound change in mentality to look at nature in a different way. Since, they say, "the idea that economic growth is independent of the health of the environment and that humanity may indefinitely extend its economy is a dangerous illusion." To counter that deviance, we must begin by mastering demographic expansion and reducing our excess consumption of natural resources, a good part of which serves to satisfy superfluous tastes and not fundamental needs. Pisciculture and aviculture, for example, cost less for transport and in fuel oil than raising pigs and beef, combined in the sacrosanct bacon cheeseburger...
Another angle of attack: the services the biosphere offers are numerous and free. It supplies raw materials, natural water filtration systems, carbon storage in forests, prevention of erosion and floods by vegetation, plant pollination by insects and birds. That last activity alone weighs in at $1.5 billion dollars in the United States. So, it would be desirable to evaluate the cost of the services nature offers and to integrate it into economic calculations to assure the protection of those services.
To finance the development of protected areas - now too few and too fragmented - Paul Ehrlich and Robert Pringle propose to appeal to private foundations dedicated to conservation. Which costs the taxpayer less and allows significant sums to be generated. In Costa Rica, a fund of this type, Paz con la naturaleza, raised 500 million dollars, a sum that will serve to finance the country's conservation system. We may also associate shepherds and farmers more closely with the preservation of biodiversity by avoiding imposing decisions on them over which they have no control and on the condition that they personally benefit from that preservation. That end may be reached through explanations and better education in the field. But there is nothing to prevent the restoration of damaged habitats as well. However, the two researchers worry about the growing divorce in industrialized countries between the population and nature, a divorce due to intensive multimedia use. They remark that, "in the United States, the rise of electronic media has coincided with a significant reduction in visits to national parks after fifty years of uninterrupted growth." And it seems that similar phenomena have occurred in other developed countries. Thus, with a definite sense of the right moment, Paul Ehrlich and Robert Pringle propose to add an ecological dimension to the best-known virtual worlds, such as Second Life.
The Great Extinctions of the Past
The beginnings of life go back 3.7 billion years. But it took until the explosion of the Cambrian, 500 million years ago, before the first complex marine organisms appeared. Since that time, five great extinctions have taken place.
The First, 440 million years ago, caused the disappearance of 65 percent of all species, all marines. Significant glaciations followed by warming had provoked great fluctuations in sea levels.
The Second, 380 million years ago, caused the death of 72 percent of - essentially marine - species. The catastrophe would have been due to a global chilling, following the fall of several meteorites.
The Third, 250 million years ago, was so vast that life almost didn't recover from it. It is estimated that 90 percent of all species (marine and terrestrial) disappeared. The causes of the catastrophe are still being debated, but people think that immense lava flows in Siberia, perhaps provoked by an asteroid fall, profoundly changed the climate and reduced the amount of oxygen dissolved in the seas' waters.
The Fourth, 200 million years ago, is associated with the opening of the Atlantic Ocean and significant lava flows that warmed the climate. Sixty-five percent of all species perished.
The Fifth, 65 million years ago, is the best known because it is associated with the disappearance of the dinosaurs and of 62 percent of species. The causes proposed are an asteroid fall in the Gulf of Mexico and significant lava flows in India.
Closer to us, during a period from 50,000 to 3,000 years ago, half the great mammal species weighing over 44 kg. disappeared. Some researchers primarily incriminate humans and consider that the sixth extinction, the one due to Homo sapiens's behavior, has already begun.