The Science Of The Next 150 Years: 100 Years in the Future
The first projection of species extinctions came in 1980—a prediction I made in a report for then president Jimmy Carter. It concluded that the pace at which we were losing tropical forests to logging and development would cause the extinction of 15 to 20 percent of all species by 2000. The calculation was not far off. Today's Red List of Threatened Species, from the International Union for Conservation of Nature, estimates that 13 percent of bird, 25 percent of mammal and 41 percent of amphibian species face possible extinction.
Many species are on a path to become what scientists term the “living dead”—populations so small that extinction is inevitable. A century from now most of the big carnivores—including lions, tigers and cheetahs—will probably exist only in zoos or wildlife areas so small as to be quasi zoos. The same fate may await all rhinoceros and elephant species and our closest wild relatives: the two gorilla species, orangutans and chimpanzees.
Our first report in 1980 called the numbers but was overly simplistic as to the forces driving extinctions. Since then, these forces have gained in power and have grown more complex:
Invasive species play a much bigger role. Throughout Oceania the brown tree snake has devastated island bird species, including the Guam rail. Feral animals are causing a wave of decline and potential extinction of native mammal species across northern Australia. In the U.S., three new species have arrived in recent years where I live in northern Virginia: the Asian tiger mosquito, an ant species that attacks electric insulation, and brown marmorated stink bugs. West Nile virus should also be added to the list. One indication for how much things have changed is that a book on pythons in the U.S. has even been published.
Natural habitat has declined. Less than 30 percent of African savanna remains intact; the African lion population has plummeted by 90 percent. Still other threats such as “bushmeat” hunting affect mammal and bird populations. Poaching for rhino horns and elephant ivory has become so rampant that Interpol has made wildlife crime a serious priority. By the next century the Borneo rhino will be very close to extinction and might survive only in picture books and collections of museum bones.
Diseases of wildlife are spreading from one end of the globe to another. Migration has led to an increase in wildlife disease. The chytrid fungus, by far the largest problem to date, has caused a wave of amphibian extinctions around the world—especially in the New World tropics, where, for the first time, an entire group of organisms, amphibians, is in the process of disappearing. Is the disappearance of frogs a harbinger of what may be in store for other animals? If such large-scale disappearances continue, we can only wonder if we will lose the great raptors such as the Philippine eagle and the harpy eagle. The magnificent large vultures of Africa and Asia already seem to be heading toward oblivion.
Humans are distorting the global nitrogen cycle. Agricultural and industrial activities mean that the amount of biologically active nitrogen in circulation has grown in the past three decades, threatening the oxygen in waterways needed by plants and fish. The carbon cycle has been altered as well, causing climate change and acidification of the oceans.
Climate change is already having an effect on biological diversity. Species have experienced changes in their annual cycles—earlier flowering times—and some have begun to move to new locales as they try to seek a suitable climate. Joshua trees are moving away from Joshua Tree National Park in California. The retreat of Arctic Ocean ice means black guillemots have to fly farther to forage for Arctic cod, causing one nesting colony to fail. Migratory species such as wildebeests in Africa and monarch butterflies across the Americas may cease. Many salmon runs may die out for lack of sufficiently cold streams and rivers to migrate to for spawning.
What we are seeing is the beginning of a tsunami of extinction in slow motion. Major upheavals are imminent. All ecosystems (of which human civilization is one) have adapted to 10,000 years of relatively stable climate, a situation that no longer holds. For the planet's biodiversity, adaptation has its limits. Species in high places can move upslope but eventually can go no farther. Island dwellers are vulnerable either because sea level is rising or because they can no longer survive changes in their habitat.
As temperatures rise 1.5 degrees above preindustrial levels, which now seems inevitable, coral reefs as we know them will cease to exist: the partnership at the heart of the coral ecosystem, between the coral animal and an alga, will break down. And the coniferous forests of western North America may be at the threshold of a major transformation: milder winters and longer summers favor the native bark beetles, with ensuing tree mortality, followed by forest fires.
Synergies among fire, deforestation and climate change will lead to a tipping point that imperils rain forests in the southern and eastern Amazon, an event that will occur sooner than if climate change alone is the threat. Indeed, dire consequences are being felt now, at 0.8 to 0.9 degree of average temperature rise. Ocean acidification threatens many life-forms, among them mollusks. At a certain point, the natural integration of ecosystems will unravel as each species acts independently to adapt to climate change. The surviving species will assemble into new ecosystems that are hard to predict in advance and difficult for human populations to cope with.
We need to come to our senses. A critical first step would be to renew our efforts to meet the goals of the Convention on Biological Diversity, which calls for formal protection to be granted to 17 percent of terrestrial freshwater ecosystems and to 10 percent of oceans by 2020. An important step would also be to lessen the human impact of climate change, which would benefit species and ecosystems. By restoring ecosystems on a planetary scale, we might be able to lower atmospheric carbon dioxide by 50 parts per million (the difference between the current carbon dioxide level and an amount that would enable coral reefs to survive).
All these actions require political will, a recognition that the planet should be managed as the biological and physical system that it is, and an awareness that the diversity of life—of which we are a part—is critical for the future of humanity.