A Prehistoric Climate — Warmed by Dinosaurs Passing Gas?


Scientists think dinosaur flatulence could have had an affect on the climate. (Art credit: Linda Bucklin/iStockPhoto.com)

A common sight 150 million years ago, sauropod dinosaurs were some of the largest animals ever to have lived on Earth. These vegetarian dinosaurs produced a lot of methane gas — could these gaseous emissions have affected their prehistoric climate?

Planet Earth is the original recycler. Today, much of the threat facing the planet comes from it simply being unable to keep up with its recycling program. You probably have heard of the potential dangers posed by the emission of greenhouse gases into the atmosphere. Greenhouse gases get their name from the fact that they trap the suns heat on Earths surface, like the walls of a greenhouse do. One important thing to remember, however, is that there is nothing unnatural about most greenhouse gases. Carbon dioxide, methane, and water vapor, for example, all have been released into the atmosphere for millennia; until relatively recently, the natural cycles of Earth always had been able to handle the amounts. Today, human industrial activity has increased the supply of these gases to levels beyond which the atmosphere can absorb and recycle them quickly. The result is that more of the suns heat gets trapped at Earths surface, and so the average temperature rises. And for planetary ecosystems that have spent millions of years growing accustomed to certain conditions, even an average temperature shift of a degree or two can have disastrous consequences.

But are humans the only living things that have been able to affect conditions on Earth so drastically? Maybe not, according to Dr. Dave Wilkinson of Liverpool John Moores University and a group of colleagues. Realizing that livestock emissions of the greenhouse gas methane (what in humans is more delicately referred to as passing gas) contributes substantially to the total supply of that gas in the atmosphere, the scientists wondered what effects methane emission from sauropod dinosaurs might have had in the past. Prevalent some 150 million years ago, these dinosaurs were some of the largest animals ever to have lived on Earth, with even medium-sized ones weighing somewhere around 20,000 kg and reaching up to 30 m in length. Like livestock of today, these dinosaurs were herbivores, and so would have used methane-producing microbes to ferment their food during the process of digestion. Therefore, also like the livestock of today, these dinosaurs would have produced a prodigious amount of gas.

“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,” Dr. Wilkinson said in a press release about the research. “Indeed, our calculations suggest that these dinosaurs could have produced more methane than all modern sources — both natural and man-made — put together.”

Wilkinson and the others in the research group, including Graeme Ruxton from the University of St. Andrews and Euan Nisbet at the University of London, based their calculations from the findings of animal physiologists that correlate methane production to the mass of the animal. They also took into account what might have been the population density of these dinosaurs. Their calculations suggest that the dinosaurs produced as much 20 million tons (520 Tg) of methane per year, which is comparable to total modern methane emissions. Before the Industrial Revolution began 150 years ago, total methane emissions are estimated to have been less than half that amount. What was the effect of this? According to the authors, Our simple proof-of-concept model suggests greenhouse warming by sauropod megaherbivores could have been significant in sustaining warm climates.

And what does this say about climate change today? The most important thing to remember is that these calculations are only estimates. Its very difficult to infer the physiology of animals that went extinct long ago. Also, methane is only one component of a number of gases contributing to the present-day greenhouse effect. Additionally, the study draws no correlation between the rise in global temperature and any detrimental effects it may have had on the dinosaurs. What the researchers believe the significant lessons to be learned from the study are not only how strange and wonderful the workings of the planet can be, but also how microbes and methane play a role in the global climate.

More to Explore
Gaseous Emissions from Dinosaurs May Have Warmed Prehistoric Earth
Did Dinosaurs Fart Their Way to Extinction?
The Greenhouse Effect and Historical Emissions

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