Is this Methane feedback mechanism a serious concern?

Given that most estimates of the oceanic source of methane to the atmosphere put it at about 15 Tg/Yr out of a total global source of 500 Tg/Yr, this would have to be a huge effect for it to make a difference globally. Also, atm. methane concentrations have flattened out and may have stopped increasing, the one bit of good news in global climate, so there is no evidence this mechanism is significant yet. Also relevant is that there is far more methane locked up in hydrates, which are potentially at greater risk of releasing a lot of CH4 to the atmosphere. Finally, if the oceans stratify to the point where the biology changes this much, the last thing we will care about is an increase in the methane.

I'm giving this an 8 on the academic interest scale and a 1.5 on the scale of things I am really concerned over.

curmudgeonly yours,

gcnp58

They can't understand why CH4 has leveled off. Then you have continental margins ,not the whole ocean system. I hate it when you guy's do that...same with acidification. Then comes the relative absorption power of CH4. Which depends on how you model the ratio of IR between CO2 and CH4.

There's more studies then you can shake your slide rule at. Though most are topic specific and you have to look for discrepancies and or collaboration. "You can find both in most."

ed: Your header stated feedback systems and not just the approval of the paper. I also mention they were topic specific.Though the ones I read didn't mention rice fields. Regardless it's going to depend on oxygenation levels and or depletion, over fertilization, higher or lower temps, interactions between certain other gas's,microbial activity,and plankton. Little of the present day methane comes from hydrate. Wetlands outweigh the ocean by at least a 100 fold. Only 1% reachs the atmosphere due to little CH4 loving unseen bugs. So I'm starting to nodd off, I'm even booring myself.

Here's a few: Bachelet and Neue, Bouwman1989,IPCC 1992,Khalil and Shearer, Becker 2004`contradictory, Doug Erwin 1993-1994, Paull 1991 regression study, Vermeij and Dorritie 1996-2002 traps volcanism.

This goes to the "prior warm periods" question - - if it didn't happen last time, or that time before that, or the time before that, etc..... then why should it happen this time?

Ken I never said it had never happened before - I said it didn't happen last time or the time before that. MWP (even if you don't think it was warmer, it's now seens as being within 0.2 degrees C - for two centuries), Roman period (not as warm, but warm and also lasting for centuries), Holocene Maximum......

We've had periods of temps that, even if they weren't equal to the max temps of the late 20th century, were above the 20th century average - periods that lasted hundreds or thousands of years - and this methane feedback scenario didn't happen.

Does that mean it CAN'T happen now? No - because we don't know all the factors.

But certainly it means we can't assume it would happen now - I'd venture to say that it means it's not likely now, unless temps shot up substantially from here.

All of the scenarios involving 5, 6, 7 degree C increases involve a positive feedback mechanism like your methane scenario - - - CO2 alone doesn't get us there.

I just don't see any evidence that another 1-2 degrees would get us there - maybe 1-2 degrees and another couple hundred years? Time at temp is important - - it's why tree lines were much higher in the Alps, and there were Alpine passages now being revealed by retreating glaciers, during the Roman empire - - it wasn't as warm but it was warm for a prolonged period.

Next question is how long does CO2 stay up there? Market forces alone will push us away from significant petroleum use within 100 years. Coal, perhaps a bit longer.

EDIT - if I'm speculating it means that all that methane could have been released in the MWP and then built up again. It means we don't know what X amount of methane would do in the atmosphere.

So, how do we know what Y amount of CO2, a much weaker heat-trapper, would do?

Surely you're not suggesting that it's a guess that it was about as warm as today during multiple periods since the last Ice Age.

Also, the ice cores would tell us if there was a lot more methane in the atmosphere during the last few warm periods, and they don't tell us that.

I agree that just because it didn't happen during the last few warm periods doesn't mean it can't happen now. We don't know all the other factors involved and perhaps they're different.

I certainly won't lose any sleep over it.

They said.

"Methane is a potent greenhouse gas that has contributed approximately 20% to the Earth's warming since pre-industrial times. " When author's make unjustifiable statements like this, you cannot trust anything else that they conclude. I think the oceans emit thousands of times this much greenhouse gas relative to methane yet they chose not to mention this. Why is this. Are they afraid of the truth, or simply want to steer around inconvenient truths. The greenhouse gas I am refering to of course is water vapor. It completely dwarfs methane or CO2 for that matter. It has its own poorly understood mechanisms for controlling temperature. Pretending they can assign a particular amount of warming to methane is arrogant and foolish.

And then they go on to admit "But despite its global significance, oceanic methane production is poorly understood. " That is certainly true.

If they would come to recognize the methane as abiotic, they might get a clue to its origins. It is not possible that it is biologic in origin IMO.

Note: Some things are just too ridiculous. I don't need a link to support my suggestion. I hope you are not foolish enough to question my suggestion that the oceans emit thousands of times more greenhouse gases than the methane refered to in the article. They in FACT cannot make the claim they made. It reveals a preconcieved notion which you obviously share. If you weren't partisan and opened your mind to science instead of socialism perhaps you would get it but we both know you are a leftists, don't we?

Why would you worry about something that is clearly speculative? They don't KNOW anything. Both sentences use the word "could."

"Tomorrow, a gigantic asteroid, traveling at close to the speed of light could crash into the earth and vaporize it." has as much actual scientific validity as the statements you're inquiring about.

Stop reading articles that are designed to make you afraid so you support a particular political viewpoint.

There are all kinds of lakes etc. that give off Methane, but where is it???Go measure it there is just a trace and no more...

perhaps if we combine this methane, with the cow methane, we could use both to power giant generators...

I'm not aware of any other studies of this particular feedback (but of course some very well may exist). The fact that this study appeared in a prominent peer-reviewed journal like Nature Geoscience certainly lends credibility to it.

(excellent answer by gcnp)

no.