Did Dinosaur Farts Change the Climate?
In 2012, a group of British scientists published a study that made headlines worldwide: sauropods — those enormous long-necked dinosaurs of the Jurassic period — may have contributed substantially to the warming of the Mesozoic climate through their intestinal gases. The amount of methane these animals produced, according to the researchers' estimates, considerably exceeded today's global cattle output. A question that sounds absurd at first glance has turned out to be scientifically worth taking seriously.
The 2012 Study: Estimating Dinosaur Methane
David Wilkinson and colleagues at Liverpool John Moores University published a 2012 estimate in Current Biology of methane emissions from mid-Jurassic sauropods. Their model was based on the assumption that sauropods like Brachiosaurus had digestive physiology similar to modern ruminants — producing methane through microbial fermentation in the digestive tract. Given an estimated world population of several hundred million tonnes of sauropod biomass, the researchers arrived at a global methane emission of approximately 520 million tonnes per year. For comparison, the entire current methane output from livestock is around 100 million tonnes annually. The study is model-based and carries significant uncertainties, but was peer-reviewed and recognized as methodologically sound.
The Jurassic Climate: Was It Really Warm?
The middle Jurassic (approximately 170–160 million years ago) was indeed significantly warmer than today's climate: polar regions were ice-free, sea levels were considerably higher, and tropical vegetation zones extended into temperate latitudes. The methane hypothesis offers a possible explanation for this warmth, but must be weighed against other factors: increased volcanic activity, higher atmospheric CO₂ concentrations from crustal processes, and different continental arrangements. Science views sauropod methane as a possible contributing factor, not as the sole cause.
Sauropods as Biological Methane Factories
Sauropods like Brachiosaurus, Diplodocus, and Argentinosaurus were among the largest land animals that ever lived — with body masses between 20 and over 70 tonnes. To meet their enormous caloric demands, they had to consume several hundred kilograms of plant matter daily. Plant cellulose cannot be directly digested by vertebrates — it is broken down by microorganisms in the digestive tract through fermentation, producing methane in the process. The larger the animal and the larger the fermentation volume, the more methane. A single large sauropod likely produced considerably more methane per day than a modern dairy cow.
Limits of the Research: What We Don't Know
The Wilkinson et al. study has clear limitations, which the authors themselves acknowledge. We do not know for certain whether sauropods actually harbored methanogenic archaea in their digestive tracts — this is an analogy estimate based on modern herbivores. Equally, global sauropod biomass can only be roughly estimated. Fossil finds allow inferences about population densities, but the uncertainties are considerable. Critics also note that elevated methane output alone can hardly explain the entire Jurassic warming. What the study does unambiguously demonstrate, however, is that the biosphere has always influenced Earth's climate — long before humans did.
Did You Know?
- The 2012 study estimates annual methane emissions from Jurassic sauropods at around 520 million tonnes — more than five times today's cattle output.
- Sauropods like Argentinosaurus, weighing over 70 tonnes, were among the heaviest land animals of all time.
- The middle Jurassic climate was significantly warmer than today — the poles were ice-free.
- Methane from animal guts is produced by methanogenic archaea, not bacteria — a commonly confused group of microorganisms.
Fun Fact
When the study was published in 2012, over 1,000 news outlets worldwide covered it — including the BBC, The Guardian, and Der Spiegel. Lead author David Wilkinson was contacted for interviews by magazines around the world. He later reported that the response completely surprised him: he had expected a specialist publication with a few hundred readers.
Sources
- Wilkinson, D.M. et al. (2012). Could methane produced by sauropod dinosaurs have helped drive Mesozoic climate warmth? Current Biology, 22(9), R292–R293.
- Seebacher, F. (2001). A new method to calculate allometric length-mass relationships of dinosaurs. Journal of Vertebrate Paleontology, 21(1), 51–60.
- Prothero, D.R. (2013). Bringing Fossils to Life: An Introduction to Paleobiology. Columbia University Press.