There have been five extinction waves in the planet's history-including the Permian extinction 250 million years ago, when an estimated 70% of all terrestrial animals and 96% of all marine creatures vanished, and, most recently, the Cretaceous event 65 million years ago, which ended the reign of the dinosaurs.
Though scientists have directly assessed the viability of fewer than 3% of the world's described species, the sample polling of animal populations so far suggests that we may have entered what will be the planet's sixth great extinction wave. And this time the cause isn't an errant asteroid or mega-volcanoes. It's us.
Through our growing numbers, our thirst for natural resources and, most of all, climate change-which, by one reckoning, could help carry off 20% to 30% of all species before the end of the century-we're shaping an Earth that will be biologically impoverished. A 2008 assessment by the International Union for Conservation of Nature found that nearly 1 in 4 mammals worldwide was at risk for extinction, including endangered species like the famous Tasmanian devil.
Overfishing and acidification of the oceans are threatening marine species as diverse as the bluefin tuna and reef-forming corals. "Just about everything is going down," says Simon Stuart, head of the IUCN's species-survival commission. "And when I think about the impact of climate change, it really scares me.
Scary for conservationist, yes, but the question arises, Why should it matter to the rest of us? After all, nearly all the species that were ever alive in the past are gone today. Evolution demands extinction. When we're using the term extinction to talk about the fate of the U.S. auto industry, does it really matter if we lose species like the Holdrige' toad, the Yangtze River dolphin and the golden toad, all of which have effectively disappeared in recent years? What does the loss of a few species among millions matter?
The more species living in an ecosystem, the healthier and more productive it is, which matters for us-a recent study by the World Wildlife Fund (WWF) estimates the economic value of the Amazon rain forest's ecosystem services to be up USD100 per hectare (about 2 1/2 acres). When we pollute and deforest and make a mess of the ecological web, we're taking out mortgage on the Earth that we can't payback-and those loans will come due.
Then there are undiscovered organisms and animals that could serve as the basis needed medicines-as the original ingredients of aspirin were derived from the herb meadowsweet-unless we unwittingly destroy them first. "We have plenty of stories about how the loss of biodiversity creates problems for people," says Carter Roberts, WWF's president. TO BE CONTINUED.
This post is republished from the article entitled "The New Age of Extinction" by Bryan Walsh in Time Magazine, April 13, 2009.
Re-Written byZARIL FAIZAL BIN ZARAL GAFFAR
Politeknik Kota Kinabalu, Sabah.
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