Confessions of a Greenpeace Dropout: The Making of a Sensible Environmentalist (61 page)

[61]
. “Gates Foundation Names New Agricultural Director,” Kristi Heim,
The Seattle Times
, January 8, 2010, http://seattletimes.nwsource.com/html/localnews/2010747556_gatesag09.html

Chapter 17 -
Biodiversity, Endangered Species, and Extinction

The term
biodiversity
was first popularized by Edward O. Wilson in his book of the same title published in 1988.
[1]
The phrases
living nature or all of life
capture the meaning of this term. The emphasis on diversity highlights the number of distinct species of life. For example, arctic climates tend to have relatively low biodiversity while tropical climates have high biodiversity (because life thrives in warm climates more than in freezing ones). In any given ecosystem there tends to be a minority of species that are quite common and a majority of species that are comparatively uncommon. This gives rise to the bio-ditty, “Species here, species there; few abundant, many rare.” You might get the impression that a species is
endangered
when it is normal for it to exist in low numbers in a particular ecosystem. These species tend to be more vulnerable to displacement or local extinction when circumstances change, that is, when new competing species evolve or invade, or when the climate changes more rapidly than usual.

In any given location there are often a number of species at the extreme extent of their geographical distribution. Every species has a preferred climate where it is most abundant. It will taper off in areas where it can’t survive due to the climate or the presence of a species it can’t compete with. At the fringes of their range these species become
endangered
because relatively small changes in climate and species composition could eliminate them from that region. When their elimination involves humans the word
extirpation
is used, as in the sentence “Grizzly bears have been extirpated from California.” As a reminder of this extirpation, the grizzly remains prominently displayed on the state flag.

As the climate has constantly changed during the comings and goings of ice sheets, ice ages, greenhouse ages, and cataclysmic events of various types and proportions, species have migrated to more suitable climes or evolved to adapt to the change. When they fail to do so, they become extinct. To this extent extinction is an entirely natural phenomenon, as natural as the evolution of new species replacing the extinct ones.

Because humans are part of nature, one can argue that it is natural when we cause species to become extinct. But that doesn’t mean it is a good or a positive thing to do. Most people feel happy that the smallpox virus is now extinct in nature; and there are many other species of vermin, parasites, and disease-causing bacteria and viruses that would not be missed if they happened to disappear—HIV-AIDS and malaria, for example. Yet most people do not want to be responsible for the extinction of anything cuddly or useful.

Until very recently humans were not concerned about the extinction of other species, even though we were clearly responsible for many of them. A few naturalists and philosophers lamented the passing of the dodo bird but most people thought, That’s life. And the dodo birds fed a lot of sailors.

Beginning with the concern for preserving wilderness landscapes that emerged during Theodore Roosevelt’s presidency and John Muir’s founding of the Sierra Club, it became popular to care about the survival of species. The extinction of the passenger pigeon in the U.S. and Canada in the 1920s elevated this concern, and people started doing something about it. Starting in around 1930, concern for species such as the California condor, wolves, birds of prey, whales, and large cats resulted in programs and policies to reverse trends toward extinction. Not all these species have been saved, but the record is a good one, proving we can prevent species from becoming extinct if we act to prevent it. There are grounds for considerable optimism that even as the human population grows larger, it will be possible to keep most of the other species that share this earth with us.

Search the Internet for “mass extinction” and you will find hundreds of websites devoted to the idea that we are in the midst of the Sixth Great Extinction, as humans drive more species into oblivion than at any other time since the era when dinosaurs disappeared. These websites contend that 50,000 species are going extinct each year and that half of all species on earth will be gone before the end of this century. This is not the result of an asteroid impact or massive volcanic eruptions; it is our doing, they claim. We humans are accused of driving the mass extinction. Here is a sample of the headlines on these web pages:
[2]

“Scientists Agree World Faces Mass Extinction” (CNN)

“Quarter of Mammals ‘Face Extinction’” (BBC)

“Half of All Species May Be Extinct in Our Lifetime” (U.S. National Academy of Science)

“Fastest Mass Extinction in Earth’s History” (Worldwatch)

“Headlong Drive to Mass Extinction” (Toronto
Globe and Mail
)

“Wave of Extinctions Sweeping the Planet” (United Nations)

“One Quarter of Primates Will be Extinct in 20 Years” (London
Times
, 2005)

“One Third of Primates Face Extinction” (BBC, 2002)

So it must be true, an unassuming reader might think. No wonder some people don’t want to have children, the planet is soon doomed and it won’t be a good place to live anymore.

Note that some of these headlines are predictive in nature (“…May Be Extinct…”) while others are written as if the extinction is already under way (“Wave of Extinctions Sweeping the Planet”). This is an important distinction, as we will see later when we consider the case of National Geographic magazine.

I began to study the mass extinction phenomenon after my trip to Nairobi in 1982. There I met the Kenyan conservationist Richard Leakey
[3]
and the British environmentalist Norman Myers.
[4]
Both had impeccable credentials and both feared we were causing a mass extinction of wild species. Norman Myers had become a kind of prophet of this belief and gave lectures about the coming collapse around the world . I listened carefully to both men when I met with them and over dinners, and I came away determined to get to the bottom of this subject.

Five major extinctions have occurred during the past 550 million years, since the time of the Cambrian explosion when large, multicellular life forms emerged.
[5]
These extinctions are clearly documented in the fossil record. During the three billion or so years before that time, when all life was microscopic, unicellular, and aquatic, there is not a sufficient fossil record to distinguish extinction events clearly.

The most devastating extinction known occurred 250 million years ago, marking the end of the Permian era.
[6]
By this time all the major forms of life that exist today had already developed. The major life forms are called phyla. All vertebrates, that is, animals with backbones, are grouped into the phylum Chordata. Other examples of phyla are mollusks (Mollusca), segmented worms (Annelida), arthropods such as insects and crabs (Arthropoda), corals (Cnidaria), and ferns (Pteridphyta). In the Permian extinction, about 90 percent of all marine species and 70 percent of terrestrial species were exterminated by what was likely either an asteroid impact, massive volcanic eruptions, or a combination of the two. Miraculously, after every major extinction event the number of living species recovered and became even more abundant than they were before the collapse. This is one of the great hallmarks of the evolution of life, particularly during the 560 million years since multicellular life forms developed. As a result, the biological diversity of living things is higher in our era than it has been at any time since life began.

The most recent mass extinction was what we call the dinosaur extinction, which occurred 65 million years ago, but it was much more than a dinosaur extinction. Tens of thousands of species of all life forms were lost in what many scientists believe was the aftermath of an asteroid impact between Florida and the Yucatan.
[7]
The environmental conditions necessary to cause such a vast extinction were extremely harsh. The sun was largely blocked by atmospheric dust and debris for years. Plant species died out for lack of light and the animals that depended on them died out with them. Nothing remotely resembling this is occurring today.

As with many catastrophe theories there is, however, a grain of truth to the current mass extinction theory. Humans are known to have caused a large number of extinctions. This phenomenon began tens of thousands of years ago as we developed tools and weapons. In Australia, the extinction of most large mammals coincided with the arrival of humans about 50,000 years ago. Similarly, the arrival of humans in the New World (the Western Hemisphere) about 15,000 years ago is strongly correlated with the extinction of mammoths, mastodons, saber-toothed tigers, and many other large mammals that had evolved long before humans arrived on the scene. Interestingly, this pattern did not occur in sub-Saharan Africa, where our hominid ancestors evolved over millions of years and where the native wildlife had the opportunity to adapt to humans as they first threw rocks and then spears.

In more modern times, a considerable number of extinctions have occurred as a result of human activity. These fall into three categories:

Overhunting and eradication.
In other words killing an entire species with clubs, spears, and guns. The dodo bird and the passenger pigeon were victims of overhunting for food; the Carolina parakeet, the only parrot that was native to North America, was eradicated by farmers because it ate their crops. The parakeets came in large flocks and as the farmer shot them one at a time the remaining birds circled around the growing heap of dead fellows until the last one was shot. Not a very good survival strategy in the face of a farmer with a gun. The evolution of human technology overwhelmed millions of years of parakeet evolution in a few decades. The species was pronounced extinct in 1939.
[8]

Conversion of native forests and other ecosystems to vast areas of farmland.
About one-third of the original area of forest has been cleared and converted for agricultural use during the past 10,000 years. Most of this clearing has taken place in the past 200 years. Some species of plants, which can’t easily migrate like birds and mammals, disappeared when their habitats were transformed to produce food for a growing human population.

The introduction of exotic species.
In particular, when Europeans colonized Australia, New Zealand, and many smaller islands in the Pacific and elsewhere, they brought with them rats, cats, foxes, snakes, and diseases not native to those places. Some species of native animals could not defend themselves from these new predators and diseases and were exterminated by them. This resulted in a pulse of extinctions as the most vulnerable native species succumbed.

There are well-documented lists of species that have become extinct due to these three human activities. The rate of extinction has slowed considerably in recent decades, partly because the most vulnerable species are already extinct, and partly because there are recovery programs in place to prevent currently endangered species from going extinct. But as the human population continues to grow there will be increasing pressure on vulnerable species.

Most overhunting for land animals and birds is now mainly an issue of illegal hunting and poaching. Tigers are poached for their hides, birds are taken for the pet trade and for their feathers, and rhinos are killed for the alleged aphrodisiacal power of their powdered horns. Ending these practices requires increased enforcement of hunting regulations and education about endangered species.