permaculture

["Lawrence F. London, Jr." <lflj@intrex.net>]

<http://news.bbc.co.uk/2/hi/science/nature/7058627.stm>
                
Last Updated: Wednesday, 24 October 2007, 07:34 GMT 08:34 UK
Climate threat to biodiversity
Simulation of asteroid hitting Earth
One-fifth of land species died out 65 million years ago
Global temperatures predicted for the coming centuries could trigger a mass 
extinction, UK scientists have warned.

The temperatures are within the range of greenhouse phases early in the 
Earth's history when up to 95% of plants and
animals died out, they say.

Experts examined the link between climate and diversity over 520 million 
years, almost the entire fossil record.

They found that global diversity is high during cool (icehouse) periods and 
low during warm (greenhouse) phases.

"Our results provide the first clear evidence that global climate may explain 
substantial variation in the fossil record
in a simple and consistent manner," said Dr Peter Mayhew of the University of 
York.

"If our results hold for current warming, the magnitude of which is 
comparable with the long-term fluctuations in the
Earth's climate, they suggest that extinctions will increase."

Warmer, wetter

The research, published in Proceedings of the Royal Society B, compared data 
sets on marine and land diversity against
estimates of sea surface temperatures for the same period.

They found that four out of the five mass extinction events on Earth are 
associated with greenhouse phases (warmer,
wetter conditions) rather than icehouse phases (cold, dry conditions).

These include Earth's worst mass extinction 251 million years ago when some 
95% of all species were lost.

"We could - at worst - be experiencing that in the next century - only a few human 
generations down the line," Dr Mayhew
told BBC News.

"We need to know why temperatures and extinctions are linked in this way."

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--
Lawrence F. London, Jr.
lflj@intrex.net
Venaura Farm http://venaurafarm.blogspot.com
Agriculture, Market Farming & Permaculture
http://www.ibiblio.org/ecolandtech



--
Lawrence F. London, Jr.
lflj@intrex.net
Venaura Farm http://venaurafarm.blogspot.com
Agriculture, Market Farming & Permaculture
http://www.ibiblio.org/ecolandtech