"Dinosaurs may be partly to blame for a change in climate because they created so much flatulence, according to leading scientists... It is even possible that the climate change was so catastrophic that it caused the dinosaurs eventual demise"
Looking back further still to the end of the Permian Period 252 million years ago 'The Great Dying' (the greatest extinction event in the earth's history) could too it has now been suggested have been caused by a runaway methane warming induced feedback loop caused by marine methane producing microbes.
So this brings me nicely onto next week's topic (the last in this group of posts focusing on the physicalities of methane, past and present) - next week's blog will be looking at OH.
Don't worry if this means nothing to you now, it is significant though, I promise, both in relation to what we've discussed in this blog and just maybe in relation to our future on earth too...
A teaser:
-GWP's, to which we are so accustomed, are reliant on residency times.
-Residency times are reliant on the metabolism and removal of GHGs after a standard period of time...
-But what happens if what's needed to remove a GHG; the ingredients to its removal are no longer available or all priorly used up?
Till next time...
The opening paragraph to an article by the well known powerhouse in scientific journalism that is the Daily Mail. The article stated a paper was about to be published suggesting the above.
Quite a headline claim! I had to investigate further and find cette paper - the paper in question was published by David Wilkinson, Euane Nisbet and Graeme Ruxton in Current Biology. It focuses in particular on sauropods, the largest of the terrestrial dinosaurs. By applying assumptions on metabolism from large present day mammals to estimate the likely density of these dinosaurs per kilometre in their known geographical habitable extent and then methane production values based on the production values of the largest modern day ruminants Wilkinson et al deduced that saurapods alone could have created comparable methane to all anthropogenic sources today, as their figure here suggests:
Quite a headline claim! I had to investigate further and find cette paper - the paper in question was published by David Wilkinson, Euane Nisbet and Graeme Ruxton in Current Biology. It focuses in particular on sauropods, the largest of the terrestrial dinosaurs. By applying assumptions on metabolism from large present day mammals to estimate the likely density of these dinosaurs per kilometre in their known geographical habitable extent and then methane production values based on the production values of the largest modern day ruminants Wilkinson et al deduced that saurapods alone could have created comparable methane to all anthropogenic sources today, as their figure here suggests:
Wilkinson et al., 2012
Comment: Interesting that they suggest this level of methane emission may have been enough to lead to the dinosaurs eventual demise mentioned... If we're emitting comparable amounts now to back then are we pushing ourselves towards a similar timely demise(!?).
Maybe this paper is a touch overzealous in their estimate for the amount of methane sauropods in particular produced, or perhaps too as to the sheer number of these massive animals that the earth was home to. The paper is not alone though in this area of discussion and there are many more papers suggesting similar relationships between atmospheric methane abundance and the status of life on earth. It highlights an important point I believe that methane is clearly a key facilitator, but also an inhibitor to life on earth depending on its levels of presence.
Taking a step slightly further back now to 200 million years ago, what caused the rapid extinction of half the earth's species and the dawn of the Jurassic? This paper is a very interesting read albeit slightly technical...
Ruhl and co propose that yes, carbon dioxide was the instigator to a preliminary global warming. It was this (relatively) minor preliminary warming though that then instigated a slightly subsequent release of isotopically depleted carbon (which they suggest is indicative of a methane release) into the atmosphere which caused the massive and rapid further warming. They form this deduction based on the otherwise inexplicable disruption of the carbon-cycle in which 12x10^3 gigatons of isotopically depleted carbon was injected into the atmosphere shortly after the initial warming - they suggest this nature and scale of release could only really be answered to by methane releases from methane clathrates (more to come on clathrates in the near future, worry not!). [For those wanting to know a little more but not to read the whole paper a brief overview of this paper's findings can be found in the fourth and fifth paragraph of this article in Science Magazine]
Looking back further still to the end of the Permian Period 252 million years ago 'The Great Dying' (the greatest extinction event in the earth's history) could too it has now been suggested have been caused by a runaway methane warming induced feedback loop caused by marine methane producing microbes.
Don't worry if this means nothing to you now, it is significant though, I promise, both in relation to what we've discussed in this blog and just maybe in relation to our future on earth too...
A teaser:
-GWP's, to which we are so accustomed, are reliant on residency times.
-Residency times are reliant on the metabolism and removal of GHGs after a standard period of time...
-But what happens if what's needed to remove a GHG; the ingredients to its removal are no longer available or all priorly used up?
Till next time...
A very entertaining read! You mention the P/T Mass Extinction, what do you think the main cause of this was? You mentioned methane but do you think this was the only cause or could other things such as the explosion of the Siberian mudtraps had an influnce as well? Looking foward to reading you next post!
ReplyDeleteHi Charlie! Thanks for commenting…. Good question good question. Sure the Siberian mudtrap theory is definitely a runner. There really are so many possibilities for a preliminary stimulus though and for whether the ‘event’ as a whole was actually several more distinct stimuli to the environment which are now quite hard to disassociate from the one massive event merely labelled as one; the 'P-T extinction event…' What is your stand?
ReplyDeleteThis is an extract from the conclusion of a paper published last year aiming to create a high precision timeline for the P-T event, it highlights the potential for such a ‘cascade of events’ - “We predict that with further work will come the deconvolution of the end-Permian extinction into a cascade of smaller, shorter-lived extinction and recovery events, driven by differences in paleogeography, biology, and environmental deg-radation.” they then go on to state “The short-lived nature of the extinction, protracted nature of the recovery, and comparison with other extinction events suggests that environmental conditions preceding the largest of the Phanerozoic mass extinctions must have crossed a critical threshold or “tipping point” from which the biosphere was unable to recover or adapt quickly enough to survive”
[Burgess et al, 2014]
Although the individual cause[s] of the P-T event are unclear what is evident is that there were very sharp extinction events follow by slow recoveries. Something I’ve been looking into is the relevance of OH in metabolising atmospheric methane (more on this next week…).
What I would suggest is that methane released/created (be it from volcanism/Siberian mudflats/methanogens/clathrates etc) may be responsible not just for rapid warming(and associated extinction event) but the long subsequent delay to recovery also. I’ll stress this is just a hunch and not something I know a massive amount about/have seen discussed anywhere specifically in relation to the P-T event. Anyway! I’ll explain more about why I have this hunch and about the importance of OH in the next post… As well as read more on the subject! Catch you soon, thanks Charlie