A new study, Could Methane Produced by Sauropod Dinosaurs Have Helped Drive Mesozoic Climate Warmth?, [PDF] in Current Biology suggests that dinosaur flatulence may have boosted global average temperatures by as much as 18 degrees Fahrenheit in the Mesozoic era over today's temperatures. The British researchers basically scaled up estimates of the amount of methane that cows produce today to the amount that might have been produced by herds of giant reptiles. Methane's global warming potential is about 25-fold greater than that of carbon dioxide.
As the BBC reports:
"Cows today produce something like 50-100 [million tonnes] per year. Our best estimate for Sauropods is around 520 [million tonnes]," said Dr. [David] Wilkinson [from Johns Moore University].
Current methane emissions amount to around 500 million tonnes a year from a combination of natural sources, such as wild animals, and human activities including dairy and meat production.
Thank goodness an asteroid slammed into the Earth 65 millions years ago to put a stop dinogenic climate change!