Temperature rise preceded four of the five mass extinctions

November 14th, 2007 - 2:45 am ICT by admin  
Scientists led by Peter Mayhew from the University of York found that higher temperatures associated with four of the mass extinctions were at about the same level forecast by climatologists for the next 100 to 200 years.

Of the five mass extinctions, the most recent was the Cretaceous-Tertiary, 65 million years ago, when temperatures were about 4C higher than today, while the most devastating one was at the end of the Permian period, 251 million years ago.

An estimated 95 per cent of marine species and 70 per cent of land species were killed off. Scientists estimate the temperatures were about 6C higher than today.

Mayhew said, according to estimates of the effect of global warming on animals and plants alive today, between 20 and 30 per cent would die out if temperatures rose by 1.5 to 2.5C.

Climatologists believe such a rise is likely to take place before the middle of the century, and that rise with temperatures will also affect extinction rates.

“Our results provide the first clear evidence that global climate may explain substantial variation in the fossil record in a simple and consistent manner. If our results hold for current warming - the magnitude of which is comparable with the long-term fluctuations in Earth climate - they suggest that extinctions will increase,” said Mayhew.

Tim Benton, of the University of Leeds, said: “When you look at the short-term, ten-million-year fluctuations we’ve shown there is quite a strong correlation between when things warm up and an increase in extinction rates.”

During each of the mass extinction events in the past 525 million years, at least half of the animal and plant species were wiped out.

Only the first global mass extinction was linked to lower temperatures, when vast numbers of marine creatures died as glaciers formed and sea levels dropped.

The study appears in the journal Proceedings of the Royal Society, reports Times Online. (ANI)

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