2012-02-25 11:32:07M E T H A N E
Agnostic

mikepope_9@hotmail...
118.208.186.152

I have written a 2 part article on Methane.  Part 1 is here.

I would greatly appreciate it if SkSers would cast a very critical eye over it and suggest any changes they think necessary. 

In the meantime I shall continue my struggle with 3 graphics yet to be inserted.

2012-02-25 11:34:50
jg
John Garrett
garrjohn@gmail...
98.112.44.167

I don't want to take away the fun of doing graphics for anyone else, but if would like my help the graphics, let me know. 

jg

2012-02-25 11:34:56
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.81.235

Clicking on your hyperlink yields a 'file not found' message.

2012-02-25 11:57:59
Chris Colose

colose@wisc...
169.226.41.99

Rob, add or remove the "http://" part of the link

2012-02-25 12:41:40
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

http://www.skepticalscience.com/METHANE-1.html

2012-02-28 13:58:17
Sarah
Sarah Green
sarah@inlandsea...
67.142.177.27

A few comments:

Define anoxic as low or no oxygen.

I don't think combustion should be in the first list; you really mean decay of waste left from any kind of land clearing. It's confusing to call that combustion waste.

Should point out somewhere that fracking = extraction of methane; I find it surprising that most people don't know that. Actually, most people don't know that the natural gas they burn is methane. 

You may want to point out that CH4 is much less soluble than CO2. So actually the "water sink" is really just a conversion of some CH4 to CO2 before it escapes from the water. "Sink" suggests that water can pull CH4 out of the air.  Actually, the "land sink" is the same principle. Can you put both in a category of "trapping before release"? (or something with a better name?). People are likely to misunderstand the chemical rxns as saying that CH4 can react with O2; point out that this is only done by bacteria (or fire).

Really, oxidation by OH is the only true sink once it reaches the atmosphere. 

2012-02-28 21:19:56
John Mason

johntherock@btopenworld...
86.133.202.150

I'm having problems with this paragraph:

Methane (CH4) is a greenhouse gas produced by the action of bacteria causing decay of organic matter, usually in anoxic conditions.  It occurs as a result of human activity and naturally, primarily as a result of methanogenesis.  CH4 is also formed by thermogenesis in the earths crust from which it vents during seismic and volcanic activity and during extraction of fossil fuels.

 

How about:

Methane (CH4) is a greenhouse gas with both anthropogenic and natural sources.  In nature, it occurs as a consequence of two key processes, namely methanogenesis (formation by microbial activity) and thermogenesis (formation by geological processes within the Earth's crust).

 

then go on to treat the anthropogenic causes?

Cheers - John

2012-03-03 10:20:35
Agnostic

mikepope_9@hotmail...
118.208.23.41

Sarah ... Thankyou for your comments, all of which I agree with and have reflected in re-write of relevant parts.

John ... Thankyou also.  I have made the change recommended by you but do not understand why it would be less problematic to delete reference to CH4 emissions associated with vulcanism and siesmic activity.  After all, such emissions do occur, don't they?

Everbody - any more comments please?

2012-03-03 10:32:14
John Mason

johntherock@btopenworld...
86.133.202.150

Agnostic - yes, to an extent they do - but I would say that the key geological source of methane is kerogens going too far through the oil-window so that they are cracked down to methane, which via its buoyancy finds its way to the surface via all sorts of conduits. That is essentially a process within sedimentary basins.

I'll try and see if I can find a value for volcanogenic methane emissions tomorrow. I cannot imagine it to be that much TBH, unless you have unusual scenarios like magma pushing up through especially carbonaceous rock-units. It happens, certainly, and perhaps notably at times in the past, but coincidences like that are uncommon all the same.

Cheers - John

2012-03-06 14:01:27
Sarah
Sarah Green
sarah@inlandsea...
67.142.177.26

I'm stumbling on the distinction between natural and human sources. For example here:

The volume of CH4 entering the atmosphere as a result of human activity is not accurately known though estimates suggest in 1999 it was ~50% - 60% of total emissions.  Emission of natural CH4 are likely to exceed human emissions by 2020. 

A key take-home point shoul dbe that prehistoric CH4 levels in the atmosphere were in a dynamic balance. Humans have impacted (accelerated) the natural sources and added some new ones (e.g. by releasing long-buried gas).

We can't just turn off the CH4 spigot, because heating the planet has opened a bunch of new spigots from drips and leaks to loosening the valaves on potential firehoses (permafrost, clathrates).