A new assessment conducted by 174 scientists from around the world underscores a growing concern about the health of the world's biodiversity, quantifying the rate of decline among vertebrate species on a global scale for the first time. The team's results support the idea that our planet is currently experiencing its sixth mass extinction—nearly one fifth of all known vertebrate species are currently classified as Threatened on the International Union for the Conservation of Nature (IUCN) Red List, and an average of 52 species of mammals, birds, and amphibians move one category closer to extinction each year. The team, which includes California Academy of Sciences mammalogist Dr. Galen Rathbun, notes that over the past four decades, species extinction rates have exceeded normal background rates by two to three orders of magnitude. However, the team reports that species losses and declines would have been 20% worse in the absence of conservation efforts to protect threatened species. Thus, while current conservation efforts remain insufficient to offset the main drivers of biodiversity loss—including habitat loss, over-exploitation, and invasive alien species—targeted conservation efforts have had a measurable positive impact on the planet's vertebrate species. The research is reported in the October 26 issue of Science Express, the website for the journal Science (publication in the print version of Science will follow at a later date).
It could have been 20% worse. But the extinction acceleration is three or four orders of magnitude above the natural background rate. So human interventions against extinctions have pretty small impacts as compared to human interventions that cause faster rates of extinction.
Accomplished entomologist E. O. Wilson says we are losing biodiversity.
"The 'backbone' of biodiversity is being eroded," said the great American ecologist and writer Professor Edward O. Wilson, at Harvard University. "One small step up the Red List is one giant leap forward towards extinction. This is just a small window on the global losses currently taking place."
To assess the status of the world's vertebrates, a large, international research team lead by Michael Hoffmann of the International Union for the Conservation of Nature Species Survival Commission and Conservation International analyzed data for over 25,000 vertebrate species categorized on the International Union for the Conservation of Nature (IUCN) Red List.
They report that one-fifth of species is classified as Threatened, and this figure is increasing. On average, 52 species of mammals, birds and amphibians move one category closer to extinction each year. The tropics, especially Southeast Asia, are home to the highest concentrations of Threatened animals, and the situation for amphibians is particularly serious.
Dr. Jack Musick, emeritus professor at the Virginia Institute of Marine Science, has overseen a global study suggesting that 33 percent of shark, skate, and ray species are threatened with extinction.
The work is part of a major new study of vertebrates by the International Union for Conservation of Nature (IUCN), the world's oldest and largest environmental network. The IUCN study shows that conservation actions have benefitted a few species of vertebrates around the world during the last few decades, but are too few and far between to slow an overall rapid increase in the number of threatened species.
A summary of the study, "The Impact of Conservation on the Status of the World's Vertebrates," will appear in this week's issue of the flagship journal Science. The study is based on an on-going appraisal of the IUCN Red List, the worldwide standard for assessing the status of species. Red List categories run from "least concern" to "near threatened," "vulnerable," "endangered," "critically endangered," "extinct in the wild," and "extinct."
Among the brightest spots of hope: recent scenarios show that slowing climate change and deforestation can go hand-in-hand to reduce biodiversity loss thanks to "significant opportunities to intervene through better policies, such as those aimed at mitigating climate change without massive conversion of forests to biofuel plantations" says Dr. Leadley. But action must be taken quickly, as the study indicates the window of opportunity is closing rapidly, as differences in policy action taken now could either lead to an increase in global forest cover of about 15% in the best case or losses of more than 10% in the worst case by 2030.
Overfishing is one cause of extinctions. With rising human populations and rising buying power I expect that trend to continue.
For example the continuing overall decline in populations of large-bodied fish species due to over-fishing, the poleward migration of marine species at a rate of more than 40 km per decade due to climate change, and the 10 to 20% decline in the abundance of terrestrial species by mid-century primarily due to land-use change.
Regards the land use changes: The human population has gotten so large and its demands on the planet so great that humans are out-competing and wiping out other species. Expanding cities and farms and logging operations all cut into habitats. That trend will continue.
I do not expect the gloomier predictions of species losses to be prevented. Human population growth and industrialization will drive humans to use more of the Earth's surface and oceans for human purposes. Less of the planet will be left in its natural state.
|Share |||Randall Parker, 2010 October 27 12:20 AM Trends Extinction|