New estimate of effect of methane on climate

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Hi Bystander,

About a century is the figure that is quoted all over the place. I'll try to find a source, but do you know different?

I do not follow you reasoning:

"!.5x1015 kg divided by the annual terrestrial biological production of starch and cellulose will get you within a factor of two or three; relative productivity of the marine environment (half as much, equal to, or twice as much as terrestrial) is still being argued."
 
Hi again Andre,

“The big question is why the troposphere is not keeping pace with the surface warming despite all CW attempts to conceal that.”

With respect to the discrepancy between surface and tropo- I accept it.(were you referring to me?) I don’t know the reasons and from what I read neither do the climate science community.

Your Hansen link is interesting. As an aside, when you compare the graph quoted there to the GISS Graph Annual Mean Temperature Change in the United States.(Annual and five-year running mean surface air temperature in the contiguous 48 United States relative to the 1951-1980 mean.) Available here http://data.giss.nasa.gov/gistemp/graphs/Fig.D.pdf [Broken] there seem to be a difference, in Hansen’s an upward trend from 1880 to 1920. Anyone know why?

I hate to tread on Hansen’s feet, after all I’m no expert. But: The graph is below the 1951 to 1980 mean until 1920, oscillating between 0 and -1 anomaly until it then rises to a peak in the 30s and descends to a minimum in the late 60s. From then on it goes upwards and recently indicates a downwards slope.

Carry out a simple visual integration on it. It becomes clear that when counting the area between the red trend line and the 0 anomaly centre line, the area is predominantly negative in the first part of the graph and becomes predominantly +ve (above the 0 anomaly line) in the second part. i.e there is a clear trend from below the 0 anomaly to above the 0 anomaly with time. This is a real long-term component, i.e. it is there, it could not continue indefinitely without exposing itself eventually. The question that this graph cannot answer is what the significance is, if any. Hansen is totally correct in pointing out that this does not agree with the global trends and that understanding this will be a key pre-requisite for improving modelling.

But as this is a regional indicator it cannot be used to question the global temperature which, on a global basis, by all measuring means, shows a clear upward trend across the data available for those measuring means.
 
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Correction "Hansen is totally correct in pointing out that this does not agree with the <degree of increase> shown in global trends... "
 
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CobblyWorlds said:
As an aside, when you compare the graph quoted there to the GISS Graph Annual Mean Temperature Change in the United States.(Annual and five-year running mean surface air temperature in the contiguous 48 United States relative to the 1951-1980 mean.) Available here http://data.giss.nasa.gov/gistemp/graphs/Fig.D.pdf [Broken] there seem to be a difference, in Hansen’s an upward trend from 1880 to 1920. Anyone know why?.
I flicked back and forth between the two graphs. They're awfully close, but not quite the same, aren't they? Ex: the 1889 point is off in the two graphs.

Can you provide an article that references your graph? They may be correcting for some factor that wasn't corrected for in the other link.
 
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Bystander

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CobblyWorlds said:
Hi Bystander,

About a century is the figure that is quoted all over the place. I'll try to find a source, but do you know different?

I do not follow you reasoning:

"!.5x1015 kg divided by the annual terrestrial biological production of starch and cellulose will get you within a factor of two or three; relative productivity of the marine environment (half as much, equal to, or twice as much as terrestrial) is still being argued."
Residence time: for a "steady state" system, quantity in a reservoir divided by flux is residence time. Quantity? 1.5x1015 kg. Flux? Sum of ALL processes contributing to addition or removal of material to or from the reservoir: for CO2 in the atmosphere, photosynthesis is the big removal mechanism. How much plant mass (dry) is produced in a year's time?

Your 100 year residence time implies a global productivity of 15 billion tons of vegetable matter a year, ton per terrestrial hectare per annum, pick your units. There are "estimates," we know what those are worth, that marine productivity is two to three times that of dry land, cutting the ton per hectare down to 1/3 or 1/4. When's the last time you raked leaves? Mowed lawns? Cut wheat? Baled hay? Ran cattle in N. Mex. or Wyo.? 1/3 to 1/4 ton per hectare per annum is very high for the Sahara, Antarctica, Kara Kum, Serengeti, but is NOT close to a reasonable figure for average global productivity.
 
Thanks for that Bystander, I did have the figure wrong and from a textbook ("nd hand O.U. text book) it's 3.6 years. Where the 100 years came from I do not know.

I get the basic derivation of the residence time, what I didn't get was how you'd go about estimating the flux. But even your rough calculations show how wrong the century was.

Notwithstanding my screw up the 3.6 years still dwarves the 11 days for water - which was my original point in stating it.

Thanks again.
 
"Can you provide an article that references your graph? They may be correcting for some factor that wasn't corrected for in the other link."

Hi Patty,

As I post in my breaks (and at times when I shouldn't) at work I've not got the time to look into it(and I've not got the 'net at home). I don't consider the issue significant enough for the purposes of my argument to look into it at present. Sorry.
 

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