British scientists have estimated the total methane output of one class of dinosaurs at a point around 150 million years ago. Amazingly it’s more than the total methane produced in the world today and could theoretically have prolonged a period of historically high temperatures.
The work was carried out by a team led by David Wilkinson of Liverpool John Moore’s University and published in Current Biology. It looked at sauropods, the group of giant land-based vegetarian dinosaurs that includes the
Wilkinson’s calculations are extremely rough and ready, partly because of their simplicity and partly because there’s inherently no way to validate them. He worked by looking at the methane produced by cows in comparison to their mass, then extrapolated that ratio to the sauropods.
In both cases, the combination of vegetation food and stomach microbes produces methane gas in the form of flatulence. That methane can absorb the sun’s radiation, and trap it in the atmosphere, raising temperatures.
Taking in to account the sauropod population at the time, Wilkinson came up with a figure of 520 million tons a year, which compared to an estimated 500 million tons a year from all sources today, including man-made sources.
The higher methane output of the dinosaurs compared with cows isn’t necessarily just a matter of size. They could reach vegetation on tree-tops and had a wider range of land on which to live and graze (permanent ice caps didn’t exist.)
Even without humans and industry, methane levels at the time may have gone beyond that produced by the sauropods and other creatures. Forest fires and leaking gasfields — neither of which would have been limited by human intervention — could also have played a part. Because of this, Wilkinson estimates that the total methane levels may have been 6 to 8 parts per million, or 3 to 4 times today’s levels.
While historical figures suggest that this didn’t lead to a rise in temperatures (instead that came 50 million years earlier, likely by a methane release from the seafloor), it’s certainly conceivable that dinosaur flatulence helped maintain the high temperatures. However, Wilkinson pointed out that his work simply demonstrates a theory and it’s not one that is ever likely to be proven.