Kind of unexpected that this hasn't been looked at before esp. given that methane is a greenhouse gas. Didn't you kind of think that we already knew all about all sources of methane before pronouncements started being made about the 'dominant source of methane is cows' or some such. If it turns out humans are a significant contributor just by _being_, then human population growth becomes a consideration ... one that is rarely mentioned btw in climate change discussions.
This has been overlooked, because the methane produced by the newly discovered path is not produced by a normal function of the living beings.
It is caused by an undesirable defect of all living beings. Most of the structure and constituents of the living cells have their origin before large concentrations of free dioxygen have appeared on Earth, and they are easily damaged by it. The living beings that have adapted to live in the presence of dioxygen have acquired many adaptations to protect their sensitive parts from the action of the dioxygen, but these adaptations are not perfect and a little damage may still occur.
Unlike in certain bacteria (the methanogenic archaea), which transform a part of their food into methane to produce energy, this new method of methane generation does not have any advantage for the living beings where it occurs.
On the contrary, it is a byproduct of a process by which the ambient dioxygen destroys a small part of the living matter, which is a loss for the cells where it happens.
This methane is like the soot from an incomplete burning of some organic matter.
> human population growth becomes a consideration ... one that is rarely mentioned btw in climate change discussions.
Not in the context of methane generation, but I'd imagine there's scarcely a discussion of climate change that doesn't include the impact of humans in general, and human population growth in particular.
There's a subtle difference in examining the actual footprint of a human body, versus the environment that exists to support the humans. It's easy to say that, because we examine air conditioning, automobiles, etc, but how often do we consider the volume of air that we breathe compared to these other impact factors?
I haven't seen it done so much, maybe not ever. I'm biased, of course, from reading studies that interest me.
As TFA states, the generation of methane in cows (and others) is mostly from archaea bacteria. That other processes might generate small amounts of methane during "oxidative stress", which often equates with serious cellular damage, is kind of irrelevant to greenhouse effects.
I think I read somewhere that if we simply composted near 100% of all compostable organic waste that it would reduce methane production by around 8-10% (from memory). So basically a trivial solution can't even be enacted by humans.
The reason it's no longer the hot topic is because industrialised nations' populations do not grow - as living standards increase, birth rates approach parity or slight shrinkage.
So the good news is that to control population growth we should do the thing that we should be doing anyway: get the whole world up to a sustainable high living standard.
>Methane on Mars is expected to have a rather short lifetime – around 400 years – because it is broken down by ultraviolet light. Atmospheric mixing (for example, by winds) should quickly lead to a more or less uniform background concentration. But previous observations hint at seasonal variations in methane abundance, with concentrations varying with location and time. If this is correct, there must be an active source to replenish the supply and, at the same time, a relatively quick way of removing it in order to account for the apparent rise and fall in the measurements.
