The sixth extinction

2010-04-03 00:00

MODERN humans have been on the planet for only 200 000 years and have managed to sow destruction on it in a short time — the past 65 000 years.

Whether humankind still has time to evolve further and eventually to survive is uncertain.

This was the view expressed by Professor Bruce Rubidge, director of the Bernard Price Institute of Palaeontology at the University of the Witwatersrand (Wits), and Professor Terence McCarthy of the department of mineral geochemistry at the close of the recent Darwin 200 Lecture Series at the University of the Free State.

The known fossil data show that species regularly become extinct, but that extinction takes place gradually. Sometimes, however, short-burst mass extinctions occur, with 30 already having been recognised.

Five of these were catastrophic, which collectively led to the extinction of 70% of all life, according to McCarthy in his latest book, How on Earth?

Many researchers think the sixth massive extinction has already started, or is confronting us.

The mega fauna (mammals above 50 kg) are dying out, says Rubidge.

It was initially thought that this is related to the last Ice Age 12 000 years ago. But new evidence shows that the cause is human overutilisation of resources over the past few thousand years.

And it became worse in the 1500s, when new worlds were explored as a result of sea voyages of discovery.

Most of the mega-fauna that have lived in the past 100 000 years have already become extinct.

However, all species regardless of size are now vulnerable and the rate of extinction is 10 000 times higher than usual — up to 50% of species could be lost by 2050.

Humankind has become totally specialised and evolution’s lesson is that the more specialised an organism is, the more vulnerable it is to any change in the environment.

When a threat comes, there is not enough time to adapt evolutionarily, and the species dies out.

So if there were a total crop failure globally three years in succession, humankind would become extinct, McCarthy explained.

The other danger is a global collapse of energy supply. This would lead to a shift in political power as well as the end of aid to many dependent countries.

No energy means no food. This would lead to a global breakdown of the social order and people would eat anything they could lay their hands on.

A point of no return will have been reached beyond which order will never be restored, McCarthy said. “Without the existence of a ‘big brother’ there will be permanent chaos.”

This will eventually lead to the extinction of humankind and thousands of other species — like the bell that started tolling for the mega-fauna thousands of years ago.

But such a state of permanent chaos or mass extinction could also be caused by climate change, like an ice age in which the entire north is frozen over and the south is experiencing extreme drought conditions.

Or, of course, the current global warming with its dire consequences.

Humans have no more abilities left to survive it and there is nothing left to hunt, unlike in previous eras.

Mega-volcanic eruptions (the geological data show they exist) could plunge Earth into darkness for decades. The consquences of collisions with asteroids and comets will be just as catastrophic.

One of the massive extinctions awaiting us and which has been recently predicted, is the collapse of the La Palma Island in the Canary Islands.

It is predicted that if the Cumbre Vieja were to erupt, the island would give way under its own weight and sink into the ocean.

A tsunami up to 30 metres high would hit the United States within 10 hours. ­McCarthy says the question is not whether it’s going to happen, but when.

The same is true for Hawaii, where a similar danger exists — the highest mountains on that island could implode on themselves after an earthquake. The effect on America will be catastrophic and could lead to the feared swing in the economic and political world order.

The longer a species survives, the greater its chances of extinction. Eventually all species become extinct, says McCarthy. The solution to preventing a sixth extinction, according to McCarthy, is a drastic reduction in the world population.

“If every woman is restricted to only one child, that would reduce the population by 50% within one generation. It is, therefore, possible to reverse the population explosion within a short period.”

He said there is no hope for wildlife conservation if the world population keeps growing as it is now.

Besides birth control, the Earth could be saved only by setting aside two-thirds of it (oceans included) as wilderness areas.

There should also be a more widely spread, decentralised and sustainable energy supply. If that is not done, life will collapse, everything edible will be destroyed, and all that will be left behind will be a world populated by insects.

Listen to the whole lecture series on www.ufs.ac.za/storyoflife

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