Dinosaurs
passing wind may have caused climate change
Huge
plant-eating dinosaurs may have produced enough greenhouse gas by breaking wind
to alter the Earth's climate, research suggests.
 |
| Barnes Common |
Like huge cows, the mighty sauropods
would have generated enormous quantities of methane. Sauropods, recognisable by their long necks and tails,
were widespread around 150 million years ago.
They included some of the largest
animals to walk the Earth, such as Diplodocus, which measured 150 feet and
weighed up to 45 tonnes.
Scientists believe that, just as in cows,
methane-producing bacteria aided the digestion of sauropods by fermenting their
plant food.
''A simple mathematical model suggests that the microbes
living in sauropod dinosaurs may have produced enough methane to have an
important effect on the Mesozoic climate,'' said study leader Dr Dave
Wilkinson, from Liverpool John Moores University.
''Indeed, our calculations suggest that
these dinosaurs could have produced more methane than all modern sources - both
natural and man-made - put together.''
The research is published today in the journal Current
Biology.
Methane is a more potent greenhouse gas
than carbon dioxide, with a stronger ability to trap heat.
Dr Wilkinson and colleague Professor Graeme Ruxton,
from the University of St Andrews in Scotland, began to wonder about Mesozoic
methane while investigating sauropod ecology.
Research on a range of modern species has allowed
experts to predict how much methane is likely to be generated by animals of
different sizes.
The key factor is the total mass of the animal. Medium-sized
sauropods weighed about 20 tonnes and lived in herds of up to a few tens of
individuals per square kilometre.
Global methane emissions from the animals would have
amounted to around 472 million tonnes per year, the scientists calculated.
The figure is comparable to total natural and man-made
methane emissions today. Before the start of the industrial age, about 150
years ago, methane emissions were around 181 million tonnes per year. Modern ruminant animals, including cows, goats, and
giraffes, together produce 45 to 90 million tonnes of methane.
Sauropods alone may have been responsible for an
atmospheric methane concentration of one to two parts per million (ppm), said
the scientists. In the warm, wet Mesozoic, forest fires and leaking
natural gasfields could have added another four parts per million.
''Thus, a Mesozoic methane mixing ratio
of six to eight ppm seems very plausible,'' the scientists wrote. ''The Mesozoic trend to sauropod gigantism led to the
evolution of immense microbial vats unequalled in modern land animals. Methane
was probably important in Mesozoic greenhouse warming.
''Our simple proof-of-concept model suggests
greenhouse warming by sauropod megaherbivores could have been significant in
sustaining warm climates.''
EDIT: So Mooli is really dangerous, says Rocco.
