Well you clicked on it didn’t you? Today’s
annoying link fodder amusing science story came from a new report out this week in the journal Current Biology, from a team at multiple UK universities, including Liverpool John Moores. They did a few simple calculations to estimate the methane production of dinosaurs. Take the size of a cow and scale up to the size of a sauropod dinosaur. Scale methane emissions by the same factor, adjusting for reptilian metabolism. Multiply by the estimated number of sauropod dinosaurs. Compare emissions with those by humans, cows and typically termites.*
520million tonnes a year in case you were wondering (cows and other livestock currently produce 100million tonnes a year). The total is about comparable to modern human production.
It’s a nice little piece and worth a small chuckle over. Unfortunately we live in a world where the mention of anything having even the remotest influence on climate heralds the end of the world. Plus its got two topics that everyone loves: Dinosaurs and Climate. And so, in a bid to receive the highest number of hits possible, out came the ridiculous headlines, scaremongering and some very bad attempts at interpreting the science.
So lets deal with the science here first. Firstly, it’s the gut bacteria of the dinosaurs, rather than the dinosaurs themselves, but that’s a moot point. So yes, dinosaurs emit methane, which is a powerful greenhouse gas, and so, in theory might have led to slightly warmer temperatures than would otherwise have been experienced. The total methane output of the sauropods was 520 million tonnes a year, compared to modern emissions of slightly higher (around 550 million tonnes). This is over twice that of the preindustrial total of 200 million tonnes. This would be enough methane to sustain an atmospheric concentration of 1.5-1.8ppm.
Other suspected sources of methane in the Mesozoic, including more wetlands and forest fires, in a warmer world, could have contributed 4ppm or so to the atmosphere.
Therefore we can conclude, that of the greenhouse warming caused by methane, 1/3rd would have been as a consequence of dinosaurs. (In the same way that 1/5th of current methane emissions can be attributed to farm animals). The paper doesn’t go into the climate impact of such methane other than to offer a few carefully guarded speculations. The paper is, after-all, a biology paper rather than a climate paper, and so the climate part is not really their remit.
Also contributing to the warmth of the Mesozoic were extremely high levels of carbon dioxide, so the overall impact of the sauropods is noteworthy but not the be all and end all of the story. Which makes you wonder why the media seemed to interpret it so badly.
Out came headlines proclaiming that the resultant climate change could have caused the extinction of the dinosaurs. Even some that suggested that modern climate change could have been caused by the dinosaurs, 65 million years later. Its quite infuriating, but not to be outdone, I thought I should come up with my own headline, just to make a point.
Of course, why should we let a small light-hearted piece get into the news when it could be exaggerated to such astronomical heights. The headlines, comments and even the article itself lends no real relevance to the original science.
I’m going to give as little oxygen to the bad news stories as possible (you can Google the story if you wish but I’d really rather not link to idiocy), but well done to the BBC for getting something at least sensible and Nine News here in Australia for resisting the urge to go wild with speculation.
And in another aside, you can tell just how many “news” sites write their own material, when they manage to both get the university of the authors wrong and misquote the second paragraph typo from the Daily Mail which said that the dinosaurs only emitted methane for 150 years. Which means they must have been holding all that methane in for 149,999,850 years. Either that or someone missed the word million in copy-editing.
* actually its a bit more complicated than that as you can probably imagine, and the paper is well worth a look, as their reasoning is sound and well researched.