Rabbit Advocacy Animal Matters
Too Many Extinctions: Global Extinction Crisis Worse Than Thought
The planet is in the midst of
its sixth mass extinction event, the first in 65 million years -- this time,
human caused -- and it's even worse than we imagined. A new report published in
the international journal Conservation Biology shows that across the
planet, nearly 17,000 of the 45,000 assessed species are threatened with
extinction. And the crisis is hitting the Oceanic region of Australia, New
Zealand, and the Pacific Islands especially hard, turning some of the Earth's
most prominent biodiversity hotspots into extinction hotspots. The prime
extinction drivers? Habitat loss and degradation, invasive species, climate
change, overexploitation, pollution, and wildlife disease. Hmm, these all seem
related to overpopulation.
Reining in the extinction crisis is the single greatest challenge ever faced by humanity, and it's what the Center for Biological Diversity was born to do. By battling global warming, overpopulation, overfishing, clear-cutting, strip mining, sprawl, and countless other threats, we're working to protect every branch -- in fact, every leaf -- on the evolutionary tree.
Too Many People: Center Launches Overpopulation Campaign, Members Speak Out
The human population is 6.8 billion and growing every second. The sheer force of our numbers is dominating the planet to such a degree that geologists are contemplating renaming our era the "Anthropocene": the epoch where the human species is the dominant factor affecting land, air, water, soil, and species. We now absorb 42 percent of the planet's entire terrestrial net primary productivity. We use 50 percent of all fresh water. We've transformed 50 percent of all land. We've changed the chemical composition of the whole biosphere and all the world's seas, bringing on global warming and ocean acidification.
Most importantly, we raised the extinction rate from a natural level of one extinction per million species per year up to 30,000 per year. That's three per hour.
Human activity is driving Earth's 'sixth great extinction event'
July 28, 2009 Ian Sample - guardian.co.uk
Population growth, pollution and invasive species are having a disastrous effect on species in the southern hemisphere, a major review by conservationists warns Earth is experiencing its "sixth great extinction event" with disease and human activity taking a devastating toll on vulnerable species, according to a major review by conservationists.
Much of the southern hemisphere is suffering particularly badly, and Australia, New Zealand and neighbouring Pacific islands may become the extinction hot spots of the world, the report warns.
Ecosystems in Polynesia, Micronesia and Melanesia need urgent and effective conservation policies, or the region's already poor record on extinctions will worsen significantly.
Researchers trawled 24,000 published reports to compile information on the native flora and fauna of Australasia and the Pacific islands, which have six of the most biodiverse regions on the planet. Their report identifies six causes driving species to extinction, almost all linked in some way to human activity.
"Our region has the notorious distinction of having possibly the worst extinction record on Earth," said Richard Kingsford, an environmental scientist at the University of New South Wales in Sydney and lead author of the report. "We have an amazing natural environment, but so much of it is being destroyed before our eyes. Species are being threatened by habitat loss and degradation, invasive species, climate change, over-exploitation, pollution and wildlife disease."
The review, published in the journal Conservation Biology, highlights destruction and degradation of ecosystems as the main threat. In Australia, agriculture has altered or destroyed half of all woodland and forests. Around 70% of the remaining forest has been damaged by logging. Loss of habitats is behind 80% of threatened species, the report claims.
Invasive animals and plants have devastated native species on many Pacific islands. The Guam Micronesian kingfisher is thought to be extinct in the wild following the introduction of the brown tree snake. The impact of invasive species is often compounded by pollution and burgeoning human populations on the islands, which have outstripped their capacity to deal with waste. Plastics and fishing gear are an ongoing danger.
The impact of humans on wildlife is likely to increase in Australasia and the Pacific islands. By 2050, the population of Australia is expected to have risen by 35%, and New Zealand by 25%, while Papua New Guinea faces a 76% increase and New Caledonia 49%.
More than 2,500 invasive plant species have colonised Australia and New Zealand, competing for sunlight and nutrients. Many have been introduced by governments, horticulturists and hunters. In addition, the report says, average temperatures in Australia have increased, in line with climate change predictions, forcing some species towards Antarctica and others to higher, cooler ground.
The report highlights several studies that point to serious threats from diseases such as avian malaria and the chytrid fungus, linked to declines in frog populations. An infectious facial cancer is spreading rapidly among Tasmanian devils and populations of the world's largest marsupial predator are believed to have fallen by more than 60% as a result.
Plants have also fared badly: a root fungus deliberately introduced into Australia has destroyed several species.
The report sets out a raft of recommendations to slow the decline by introducing laws to limit land clearing, logging and mining; restricting deliberate introduction of invasive species; reducing carbon emissions and pollution; and limiting fisheries. It raises particular concerns about bottom trawling, and the use of cyanide and dynamite, and calls for early-warning systems to pick up diseases in the wild.
"The burden on the environment is going to get worse unless we are a lot smarter about reducing our footprint," said Kingsford. "Unless we get this right, future generations will surely be paying more in quality of life and the environment. And our region will continue its terrible reputation of leading the world in the extinction of plants and animals."
Dead and buried
Cretaceous-Tertiary 65m years ago, the dinosaurs were wiped out in a mass extinction that killed nearly a fifth of land vertebrate families, 16% of marine families and nearly half of all marine animals. Thought to have been caused by asteroid impact that created Chicxulub crater in the Yucatan.
End of Triassic About 200m years ago, lava floods erupting from the central Atlantic are thought to have created lethal global warming, killing off more than a fifth of all marine families and half of marine genera.
Permian-Triassic The worst mass extinction took place 250m years ago, killing 95% of all species. Experts disagree on the cause.
Late Devonian About 360m years ago, a fifth of marine families were wiped out, alongside more than half of all marine genera. Cause unknown.
Ordovician-Silurian About 440m years ago, a quarter of all marine families were wiped out by fluctuating sea levels as glaciers formed and melted again.
Extinction hits 'whole families'
August 7, 2009 Victoria Gill BBC News
Whole "chunks of life" are lost in extinction events, as related species vanish together, say scientists. A study in the journal Science shows that extinctions tend to "cluster" on evolutionary lineages - wiping out species with a common ancestor.
The finding is based on an examination of past extinctions, but could help current conservation efforts. Researchers say that this phenomenon can result in the loss of an entire branch of the "tree of life". The message for modern conservation, say the authors, is that some groups are more vulnerable to extinction than others, and the focus should be on the lineages most at risk.
Lead researcher Kaustuv Roy, a biologist from the University of California, San Diego, focused on marine bivalves - including clams, oysters and mussels. The fossil record for these creatures dates back almost 200 million years. By tracing this documented timeline of evolution and extinction, the team was able to see the effects of "background extinctions" as well as the mass extinctions, such as the one around 65 million years ago during which the dinosaurs finally died out. Many species have become extinct during the relatively stable periods between those global calamities.
But even during such quiet periods, the team found that extinctions tended to cluster into evolutionary families - with closely-related species of clams vanishing together more often than would be predicted by chance.
Richard Grenyer, a biologist from Imperial College London, who was not involved in the study, told BBC News that by going "way back into the fossil record" this study provided important evidence of the patterns of extinction. "Big groups of organisms tend to be similar to one another," he explained. "Look at the large cats for example." But genetic similarities also mean, said Dr Grenyer, that "a bad effect that affects one of them, will likely affect all of them". "It's like a casino of extinctions, with the odds rigged against certain groups."
According to this pattern, the study's authors point out, extinctions are likely to eliminate entire branches of the evolutionary tree. Professor Roy said: "If you have whole lineages more vulnerable than others, then very soon, even with relatively moderate levels of extinction, you start to lose a lot of evolutionary history."
Julie Lockwood, an ecologist from Rutgers University in New Jersey, US, who did not take part in this study, explained that because extinction events "hit certain lineages extremely hard... we lose whole chunks of life." "There are examples of modern species where the same thing is happening," she told BBC News. "In seabirds for example, the same drivers - climatic change and habitat loss - are threatening whole groups of species."
Richard Greyner likened this loss to a fire in a library. "Because whole sections are lost - the whole of the physics section, or all of the romantic fiction, the overall loss is much worse than if you randomly burned every 400th book." But Dr Grenyer said that this evidence could help to drive more focused, and therefore more effective conservation efforts. "We can use this information," he said. "It doesn't make the conservation of individual species any easier, but if we know the sorts of things that affect tigers, we can infer conservation biology about the tiger's close relatives."
Comment: History repeats itself time and time again because human thought and behaviour, and decision making by leaders is reactive rather than proactive. Rather than continuing to try to accommodate the billions of people on our planet, it would be prudent to control human population growth NOW, and avert an impeding crisis that will likely become irreversible. Working together and putting aside selfish individual rights, religious beliefs, and culture, today rather than tomorrow, there may possibly be a glimmer of hope for the survival of the human race. If not, too bad, our bloody reign will be over and nature will reclaim herself. It is said that we reap what we sow, and I, for one, am rooting for our demise.
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