[greenyes] Methane Not CO2 Key to Last Global Warming

["Peter Anderson" <anderson@no.address>]

fyi- Landfills are the major source of manmade methane, and, if the shift to
on-the-cheap bioreactors goes forward, this already bad situation will
dramatically worsen in the near term.


Peter

 The Observer
Prehistoric clues put greenhouse accomplices in dock
Are these the real enemies of the earth?

Robin McKie, science editor
Sunday July 11, 2004
The Observer

It was a time when horses and rodents first evolved, monkeys took their
first swings in the trees and grasslands spread across Earth.
But the Eocene epoch was also distinguished by a remarkable climatic
catastrophe: one that has dramatic implications for mankind.
Fifty million years ago, temperatures soared to unprecedented levels and the
seas became a staggering 12C hotter than today. But researchers have found
this massive warming had little to do with carbon dioxide, the main cause of
today's climate changes. The trigger was instead rising levels of methane,
ozone and nitrous oxide, gases that are accorded relatively scant attention
by current climate treaties.
'The fact Earth got so hot because methane and other gases were increasing
is worrying,' said Professor David Beerling, of the University of Sheffield.
'We are rightly obsessed with carbon dioxide, but clearly we risk missing
other dangers.'
The discovery has been made by Sheffield and Bristol researchers who were
investigating Earth's ancient greenhouse crisis. Scientists had already
discovered the stifling temperatures that existed 50 million years ago by
studying marine fossils. Oxygen trapped in their shells leave a distinct
isotope pattern that reflects the warmth of the sea at the time.
In this way researchers have built a precise picture of Earth's past
temperature fluctuations and found that 50 million years ago it reached
levels that dwarf Earth's current climate crisis. Most experts assumed
carbon dioxide, whose levels fluctuate naturally in the air, were
responsible. Global warming today is blamed on industrial outputs of the
gas, after all.
Beerling decided to investigate and used a breakthrough made by his
colleague Professor Ian Woodward, who had discovered that stomata, the pores
on a plant's leaf, decrease in number as carbon dioxide levels rise. 'That
gives you a perfect way to study carbon dioxide on ancient Earth,' Woodward
said.
Beerling's group grew ginkgo trees in different concentrations of carbon
dioxide and then compared their leaves with those of ginkgo fossils from the
Eocene. 'Essentially, we breathalysed ancient Earth,' said Beerling.
'What we discovered gave us quite a shock. Carbon dioxide levels were no
different 50 million years ago than today's. Yet the planet was incredibly
hot - much, much warmer than it is today.'
Using climate models developed by Britain's Hadley Centre for Climate
Prediction and Research, Beerling and his collaborator, Professor Paul
Valdes, at Bristol University, analysed the meteorological parameters for
the Eocene, including data on carbon dioxide.
'The conclusion was clear,' said Beerling. 'There must have been much more
ozone, methane, and nitrous oxide in the atmosphere then.'
Molecule for molecule, these gases are much more effective at trapping solar
heat than carbon dioxide. So even modest elevations will produced striking
temperature hikes. At the time Earth was covered in wetlands, which produce
high levels of methane. This was one of the major contributors to the
runaway global warming that gripped the Earth, the Sheffield and Bristol
groups conclude. Today termites, cows and other animals are major sources of
the gas.
"...
'That is why this discovery is so important,' said Beerling. 'We are
currently attempting to control emissions of carbon dioxide to stop global
warming. But our obsession with it is making us overlook the dangers posed
by methane, and the others.
"...
'So even if we control the problem of carbon dioxide, we could still be in
dire straits thanks to these gases, which receive much less attention from
politicians and campaigners. That is the real lesson of this research.'

_________________________
Peter Anderson, President
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