dinosaurs may have impacted the climate

Many people here seem to think (erroneously) that humans, let alone plants and animals, can't have any effect on the climate or the state of the atmosphere. We all know the only reason we have 20% (or so) oxygen in the atmosphere is due to photosynthesis by plants. Its stands to reason that other animal impacts may have significant effects on the atmosphere and hence the climate. Oxygen is not a greenhouse gas by the way, but methane is...

"Inherit the wind: dinosaurs blamed for changing climate
John Von Radowitz
May 8, 2012

LONDON: Huge plant-eating dinosaurs may have produced enough greenhouse gas by breaking wind to alter the Earth's climate, new research suggests.

Like leviathan cows, the mighty sauropods would have generated enormous quantities of methane.

They included some of the largest animals to walk the earth, such as the Diplodocus, which measured 45 metres and weighed up to 45 tonnes.

Scientists believe that methane-producing bacteria aided the sauropods' digestion by fermenting their 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 the study leader, Dave Wilkinson, from Liverpool John Moores University.

''Our calculations suggest that these dinosaurs could have produced more methane than all modern sources - both natural and man-made - put together.''

The research was published yesterday in the scientific journal Current Biology.

Methane is a more potent greenhouse gas than carbon dioxide, with a stronger ability to trap heat.

Dr Wilkinson and a 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 a few dozen a square kilometre.

Global methane emissions from the animals would have amounted to about 472 million tonnes a year, the scientists calculated.

The figure is comparable to total natural and man-made methane emissions today. About 150 years ago, methane emissions were about 181 million tonnes a year.

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.''"

http://www.theage.com.au/environment/climate-change/inherit-the-wind-dinosaurs-blamed-for-changing-climate-20120507