by Amanda WomacOver the course of Earth’s history there have been five significant mass extinctions, according to Dr. Jack Sepkoski and Dr. David Raup in a 1982 paper titled “Mass extinctions in the marine fossil record,” published in the journal “Science.” The first great extinction took place around 440 million years ago and wiped out 85 percent of marine animal species. In the second, known as the Late Devonian extinction, nearly 70 percent of species were eliminated over a prolonged period of time, possibly 20 million years. Earth’s largest extinction occurred about 245 million years ago. Up to 95 percent of all animals were lost in what is known as the Permian-Triassic extinction, or the “Great Dying.” Sea creatures suffered most in the fourth mass extinction, which took place 200 million years ago.
The most familiar mass extinction took place 65 million years ago during the Cretaceous-Paleocene transition, in which three-quarters of all species, including dinosaurs, were eliminated. Possible causes for these extinctions are volcanic eruptions, meteorites colliding with the Earth and a changing climate. Biological diversity and richness took upwards of 10 million years to recover, yet once a species is gone, it is gone forever. Most biologists, including E.O. Wilson, renowned Harvard University professor, believe we are moving toward another mass extinction that could wipe out half of all species on the planet in the next 100 years. Although climate factors into the equation for the upcoming extinction, finger point at one single species as the cause for the massacre: humans.
The current extinction rate is 1,000 to 10,000 times faster than extinction rates over the past 60 million years. For most of geological history, new species evolved faster than existing species disappeared, so biological diversity increases. Now, however, evolution is falling behind and humans are the main culprit. Scientists estimate that 10-15 million species inhabit the planet today, yet thousands of modern species have been lost for good, some before scientists even discover them. Across the globe, consumption drives habitat destruction and fuels extinction. What people need to survive and what people want are fused and muddled by cultural conditioning. Industry manufactures cheap, plastic crap most people throw away in five years and replace with an equally cheap, plastic piece of crap, which prolongs a cycle of consumption that is killing other species.
State of the SpeciesThe International Union for the Conservation of Nature and Natural Resources (IUCN), now known as World Conservation Union, released the 2007 Red List of Endangered Species Sept. 12. According to the list, 16,306 species are threatened with extinction, up from 16,118 last year. The total number of recently extinct species has reached 785, and 65 species are only found in captivity or in cultivation. One in four mammals, one in eight birds, one third of all amphibians and 70 percent of the world’s assessed plants are in jeopardy.
“This year’s IUCN Red List shows that the invaluable efforts made so far to protect species are not enough,” said Julia Marton- Lefèvre, director general of the IUCN. “The rate of biodiversity loss is increasing, and we need to act now to significantly reduce it and stave off this global extinction crisis. This can be done, but only with a concerted effort by all levels of society.”
The IUCN began in 1948 following an internationial conference in Fontainebleau, France, and brings together 83 states, 110 government agencies, more than 800 nonprofit organizations and 10,000 scientists and experts from 181 countries. Its headquarters are in Gland, Switzerland.
Species vanish due to a number of different factors, but the most pressing is loss of habitat. Most species on the Red List have lost over half of their habitat and breeding grounds. Resource extraction displaces many species and hampers reproduction. Invasive species contribute to species decline. Global trade provides plenty of opportunities for non-native species to invade.
American chestnuts thrived in Eastern forests until a fungus arrived on ship from Asia in 1904 causing a blight that destroyed most chestnut trees by 1950. Other species have suffered the same plight and face similar futures unless humans curtail habitat destruction and prevent invasions.
Gorillas and seeweeds, goodbyeAccording to the Red List, groups threatened with extinction include humans relatives. The western lowland gorilla has moved from endangered to critically endangered, decimated by hunting for bushmeat markets and the deadly Ebola virus. Population numbers have decreased more than 60 percent over the past 20 years, and scientists worry gorillas will not be around too much longer.
“Great apes are our closest living relatives and very special creatures,” Russ Mittermeier, head of IUCN’s Primate Specialist Group, said in an interview with the Associated Press. “We could fit all the remaining great apes in the world into two or three large football stadiums. There just aren’t very many left.”
The Sumatran orangutan is listed as critically endangered, and the Bornean orangutan is endangered. Both species are threatened by habitat loss due to logging, legal and illegal, and forest clearance for palm oil plantations.
For the first time in history, coral has been added to the Red List. Ten species of coral located in the Galapagos Islands were listed, with two in the critically endangered category. Climate change is a major factor in coral decline. Seventy-five various seaweeds from the same region have been added. Warming water inhibits cold-loving varieties, and overfishing removes predators from the food chain, resulting in an increase in sea urchins and other herbivores.
In Asia, the Yangtze river dolphin is listed as critically endangered, possibly extinct. India and Nepal’s gharial, a large aquatic reptile, is critically endangered due to habitat loss. A population decline of 58 percent over the past 10 years caused by dams, irrigation projects, sand mining and artificial embankments, has reduced its domain to two percent of its former range.
In North America, 723 species of reptiles were added to the IUCN’s Red List. Ninety percent of these are threatened with extinction. Vultures are in crisis due to a drug used to treat livestock. Almost 10,000 species of birds are listed. Over 12,000 plants are on the Red List, and the Malaysian herb, wooly-stalked begonia, has been declared extinct.
Although the outlook is grim for many species, biodiversity and conservation are gaining momentum. Conservation networks are working to enact policies that preserve habitat. Public awareness is up, and a newer generation wants to ensure biodiversity in the future. As we move forward, words of E.O. Wilson ring as true to today as in 1985:
“The worst thing that can happen during the 1980s is not energy depletion, economic collapse, limited nuclear war, or conquest by a totalitarian government. As terrible as these catastrophes would be for us, they can be repaired within a few generations. The one process ongoing in the 1980s that will take millions of years to correct is the loss of genetic and species diversity by the destruction of natural habitats. This is the folly that our descendents are least likely to forgive us.”
For a complete listing of species, see
www.iucnredlist.org
Labels: biodiversity, extinction