Extinction
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AP
The white-tipped shark used to be common. Now it's one of many species in danger of extinction, this time thanks to over-fishing. Photo by AP
Reuters
Dinosaurs were all but wiped out 65 million years ago, as were countless other species. Take a hard look and think about the ramifications. Photo by Reuters

Planet Earth is on the brink of a mass extinction event comparable in scale to the one that wiped out the dinosaurs 65 million years ago, a landmark study by an international group of scientists has concluded. It would be the sixth major extinction event in the history of the planet - but this time, the cause is man, and there's precious little time to reverse the trend.

Part is the human predilection for hunting for its own sake, but the greater part is man-made climate change.

The researchers found that extinction rates are currently 1,000 times higher than normal due to deforestation, global climate change, as well as over-fishing, which is killing off not only the fish that people like to eat, but a lot of other species as well.

Duke University biologist and conservation expert Stuart Pimm says planet Earth's time is running out. And since man is to blame, Pimm and other scientists from around the world say in their landmark study that unless humans change their behavior immediately, Earth as we know it today will soon cease to exist.

Immediately means now, not whenever mankind gets around to it.

"When you look at the range of unsustainable things that we are doing to the planet, changing the atmosphere, global warming, massively depleting fisheries, driving species to extinction, we realize that we have a decade or two," says Pimm. "If we keep on doing what we are doing, by the end of the century our planet will really be a pretty horrendous place."

Man the bounty hunter

Man has been killing animals for food and fun since prehistory, the evidence categorically shows. This February the remains of a woolly mammoth clearly bearing spear wounds on its back, dating some 13,700 years ago, was found in Siberia.

Last month scientists decided that primitive man bore greater responsibility than climate change for the extinction of the giant mammals, not only the mammoth but the giant sloth, giant ancient (and other extinct) kangaroos in Australia, the woolly rhinocerous and many more.

The scientists gauged change in climate using ice cores from the Antarctic. Then they investigated the timing of modern man's arrival at various areas around the world, compared with the timing of extinction events there. Thusly, the scientists reached a stark conclusion: humans did it.

However, while man has been responsible for killing off the big mammals and decimating fish stocks, it is man-induced climate change that is behind the looming great extinction of which scientists are now warning.

Yes, man can affect the whole planet

Pimm was lead author of a study that compared historical extinction rates to those of today. They analyzed data taken from every region of the planet, on land and at sea.

They then compared that to historical data.

"We can compare that to what we know from the fossil data and incidentally what we know from the DNA data, because data on DNA, differences between species give us some idea of the timescale at which species are born and die," says Pimm. "And when we make those two comparisons, we find that species are going extinct one thousand times faster than they should be."

The reason, he avers, is global industrialization and human encroachment into natural habitats over the last 200 years.

People prefer to think that the planet is so big that mere mortals couldn't possibly change it substantially, let alone irreversibly. That proves not to be true.

Global warming and ocean acidification are just two effects that scientists now agree, almost to a man, are being caused by human activity.

Moreover, because of lags in ecological systems, even if mankind immediately ceases all activities that are increasing the level of greenhouses gases in the atmosphere (which are behind both effects) – there is already so much extra carbon dioxide in the atmosphere that global warming, and ocean acidification, will keep increasing for decades to come.

Evolution to the rescue? Not so fast

Life – animal or plant - evolves to adapt to certain ranges in climate and environment. Some can continue to adapt when the climate and environment exceed those ranges. Many cannot.In any case, species adaptation takes time, let alone the creation of new species that will thrive in the changed conditions: and the environments around the planet are changing very rapidly.

Pimm says the last time the planet faced such elevated extinction rates was 65 million years ago.

"We lost the dinosaurs and a third to a half of all of the species. If we continue on the present course, that is how much we will lose, how many species we will lose," Pimm says. "And we know after the last time that it took 5-10 million years to recover. So if we destroy this beautiful planet that we have it isn't going to come back overnight."

During the third known Great Extinction, called the Permian–Triassic extinction event 250 million years ago, some 95% of all the species on land and in the sea died out.

But while Pimm admits, the report paints a grim picture, he says it's not all bad news.

He says conservationists now have the knowledge and technology to protect endangered species more effectively than ever before, and that targeted efforts could slow down extinction rates in years to come.

He also cites education as a crucial tool in promoting the importance of sustainability. Overall, he says the key lies in making humans part of the solution rather than the cause of the problem.

Quite. But let it be said, that efforts to use cloning to revive extinct species have not worked.Wi

With reporting by Reuters