We are in the middle of a mass extinction of life on Earth. It is the greatest extinction since the mass extinction of the dinosaurs 65 million years ago. Not only will virtually all life on Earth die, but all our knowledge about life and the universe, so arduously gained the last few thousand years, will be obliterated with it.
There have been five mass extinctions in the 3.5 billion year evolution of life on Earth, when close to 100 percent of all species were wiped out. The common name for the present mass extinction is the Sixth Extinction (popularised in the 1995 book of the name by Richard Leakey and Roger Lewin). The unique characteristic of the Sixth Extinction is that it is caused by a single species: Homo sapiens - humanity.
What is the morality of causing mass extinction? Biocide is the ultimate of all human moral violations because it is the destruction of all life on Earth.
We can trace back the start of the Sixth Extinction to the Holocene (from Greek holos whole and ceno new), the era in Earth's history that started 11,000 years ago at the end of the last glacial period or Ice Age. This was the period of human culture called the middle stone age or Mesolithic. It was when humans fashioned refined stone tools, gave up a nomadic life to live in settlements, and domesticated the first wild animals.
Around the start of the Holocene several species of giant animals died out in Europe, North America and Australia. This relatively minor extinction is called the Holocene Extinction. These huge animals were comparable in body size to modern rhinoceros and elephants, hence their nickname the megafauna. The megafauna included woolly rhinoceros, woolly mammoth, Irish elk, giant beaver, giant ground sloth, sabre-toothed cat, dire wolf, giant short-faced kangaroo and giant monitor lizard.
Humanity evolved in Africa. Then they spread around the globe during the Holocene Extinction. The timing does not perfectly coincide with the extinction of the megafauna; comparable extinctions did not occur in Africa, for example. There are also other factors to consider, such as the changing conditions when the climate warmed up and the glaciers covering the northern hemisphere shrank back towards the pole. But many scientists think the human radiation and the extinction is more than a coincidence. Humans need not have killed the megafauna directly. When the megafauna were greatly stressed from environmental pressures and balancing precariously on the edge of extinction, human activity, like hunting or disease transmission, might have finally nudged them over. There is still controversy over man's part in their extinction.
The Holocene Extinction of the stone age continues up to the present. Some notable extinctions of land and air animals are the auroch (European ancestor of domestic cattle), quagga (a zebra lookalike in east Africa), thylacine (a stripped predatory marsupial in Australia), dodo (killed off by the first European sailors exploring the islands of the Indian Ocean), and great auk (wiped out from islands in the north Atlantic Ocean).
Numbers & Rate
The rate of species extinction today appears to be similar to the rate of extinction during the previous five great extinctions in Earth's history. Thousands of animal and plant species face extinction soon, including a quarter of mammal species, one eighth of bird species and thousands of plant species.
Some scientists calculate that within a hundred years half of Earth's fauna and flora could be treading the road to extinction. Earth is home to millions of species (of which only 4,000 are mammals and 7,000 are birds) and may be losing some 30,000 species a year. And the rate is increasing as we devastate the planet. The problem is especially grim for rain forests because most terrestrial species live in them (considerably fewer species live in deserts and farm land) and humanity is clear-felling forests fast. When their forest is gone its animals have nowhere to live and die out.
The magnitude of what humanity is doing to Earth life became apparent in the 1970's. But still the extinction crisis is invisible to most people, unaware or unconcerned about it. Many scientists are so worried about the lack of concern that in 1992 over 1,500 prominent specialists, among them several Nobel Prize Laureates, endorsed the World Scientists' Warning to Humanity. But it had little effect to wake up people to the coming catastrophe.
Why are people unaware of what is happening to life? Some possible answers are:
Humanity is rushing headlong in an orgy of destruction of all life on Earth and scorning all warning signals to stop. But nature's destruction is also humanity's extinction.