A trio of respected biologists and zoologists concludes that Earth's sixth mass extinction may be unfolding slower than feared, giving time for the valuable work of cataloging the planet's species.
This file photo shows two jaguar cubs born at the Milwaukee County Zoo in November. Jaguars are an endangered species.
Milwaukee County Zoo/AP
EnlargeFor years, ecologists and biologists have warned that the planet is sliding into a mass extinction event comparable to the one that did in the dinosaurs 65 million years ago.
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But Earth?s species may not be vanishing as fast as previously believed ? providing a fresh opportunity to catalog and conserve more of them before global warming and habitat loss take a higher toll on the planet?s biodiversity.
That's the conclusion a trio of respected biologists and zoologists has reached after reviewing recent studies on extinction, the pace at which new species are being reported, estimates of undiscovered species, and the human and technological capital available for building the catalog.
When it comes to discovering and preserving biodiversity, "things aren't hopeless," says Mark Costello, a University of Auckland marine zoologist and the lead author of the analysis, which appeared in this week?s issue of Science.
Three years ago, another, larger team of biologists and zoologists estimated that if collectively countries devoted $500 million to $1 billion a year to the project of cataloging nonbacterial life on Earth, the project could be complete within 50 years.
Dr. Costello and colleagues renew that call. And their lower estimate of the number of species and a higher estimate of the people available than many thought implies the job could be done more quickly.
The stakes are high, many researchers say. Human population growth and activities ? from altering landscapes and oceans to altering climate ? are widely seen as the drivers behind the current mass-extinction event, the planet?s sixth.
"We are the asteroid," says Michael Novacek, provost and curator at the American Museum of Natural History in New York, referring to the event widely held to have triggered the demise of the dinosaurs 65 million years ago.
"This may be the most important century in our evolutionary history, where the environment is really transformed to a level where the nature of life on Earth is redefined," says Dr. Novacek, who was not part of the team performing the new analysis.
Getting a handle on the full range of nonbacterial species the planet hosts is important for a number of reasons, researchers say. A full listing of what lives where would provide important information for maintaining the health of ecosystems on which humans rely for food, clean water, and other so-called ecosystem services. And undiscovered species could represent new sources of compounds for pharmaceuticals or appear as novel structures human engineers could mimic for lighter, stronger materials.
At its broadest, the widespread loss of biodiversity before anyone has a chance to take the full measure of what's out there makes it difficult to fully grasp the ecological consequences of its loss.
Novacek and others say they are a bit surprised at the relatively low number of nonbacterial species the team estimates as living on the planet ? about half the 10 million that others estimate as realistic. And the trio's estimate for a global extinction rate ? less than 1 percent per decade ? is far below the worst-case scenario of 5 percent per decade some have estimated.
Still, Costello and colleagues acknowledge that if extinction rates are on the high side, say 5 percent per decade, half the 5 million nonbacterial species he and his colleagues estimate as currently inhabiting Earth will have vanished within 150 years.
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