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Oops,

I should have divided (not multiplied) by 1.406 in my conversion of volume to weight. That makes the 2009 global production of methane 2.26 Gt rather than 4.47 Gt.  A fugitive 3.2% of 2.26 Gt is 0.0723 Gt of methane, 105x giving 7.59 Gt of CO2 equivalent over 20 years, adding 25% to the forcing from the world-total 30 Gt of CO2 being emitted, not 50% as I calculated before.

BTW, any satisfactory tax scheme or levy,  based on 'carbon out of the ground', is going to require monitoring of sites of fossil fuel production, to determine the level of fugitive methane - not only for natural gas production but also oil and coal.  Note that 1 Gt of methane produces 2.75 Gt CO2 when burnt; a fugitive 3.2% of 1Gt produces the equivalent of 3.36 Gt of CO2.  Thus the fugitive methane has a greater global warming effect than the CO2 from burning the fuel, averaged over 20 years.

Cheers,

John

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On 22/07/2012 23:00, John Nissen wrote:
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Hi all,

Please excuse cross-posting.

Bill McKibben, of 350.org fame, [1] has a recent blog [2] in which he includes some critical figures.
 
“Scientists estimate that humans can pour roughly 565 more gigatons of carbon dioxide into the atmosphere by mid-century and still have some reasonable hope of staying below two degrees. ("Reasonable," in this case, means four chances in five, or somewhat worse odds than playing Russian roulette with a six-shooter.)”
 
How much CO2 equivalent comes from natural gas production?  In 2009 world production was 3.177E12m3.  I assume that is a liquid volume.  If a liquid, then we have conversion: 1 kg = 1.406 m3, making production about 4.47E12 kg or 4.47E9 tonnes, or 4.47 Gt.  Compare global CO2 emissions at ~30 Gt. 
 
Consider 3.2% gas is fugitive (EPA figures) [3].  Then that represents 0.143 Gt methane, or 15 Gt of CO2-equiv over 20 years at 105x CO2 - weight for weight. That adds 50% onto the CO2 emissions of around 30 Gt!  We definitely need a price on fugitive methane as well as carbon out of the ground that becomes CO2.  Note that the atmospheric burden of methane is about 5 Gt, and annual emissions are estimated as between 0.5 and 0.6 Gt. 

Any carbon tax system must take into account fugitive emissions of methane.  Howarth's work suggests that methane is worse than coal as regards carbon footprint [4], when considered over 20 years or less.

Cheers,

John

[1] http://en.wikipedia.org/wiki/Bill_McKibben 

[2] http://www.rollingstone.com/politics/news/global-warmings-terrifying-new-math-20120719?page=2
alternatively
http://www.postcarbon.org/article/1011608-global-warming-s-terrifying-new-math

[3] http://en.wikipedia.org/wiki/Natural_gas

[4] http://green.blogs.nytimes.com/2011/04/12/fugitive-methane-stirs-debate-on-natural-gas/

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On 21/07/2012 02:20, Gum Hak Doi Suthep wrote:
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Also here:
http://www.postcarbon.org/article/1011608-global-warming-s-terrifying-new-math

[snip]
[log in to unmask]" type="cite">
To:
Sent: Saturday, 21 July 2012 7:31 AM
Subject: [biochar-policy] Global Warming's Terrifying New Math ( McKibben )

 
Bill McKibben is of course well known of www.350.org

He has published an article in Rolling Stone about Global Warming:

Global Warming's Terrifying New Math

Three simple numbers that add up to global catastrophe - and that make clear who the real enemy is

www.rollingstone.com/politics/news/global-warmings-terrifying-new-math-20120719

grts
Bruno .M
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


From: Bruno M. <[log in to unmask]>




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