2010-08-27 23:16:31Basic rebuttal 29: Human CO2 is a tiny % of CO2 emissions
gpwayne
Graham Wayne
graham@gpwayne...
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Human CO2: Peddling Myths About The Carbon Cycle


Argument No.29: Human CO2 is a tiny % of CO2 emissions

Before the industrial revolution, the CO2 content in the air remained quite steady for thousands of years. Natural CO2 is not static, however. It is generated by natural processes, and absorbed by others.

As you can see in Figure 1, natural land and ocean carbon remains roughly in balance and have done so for a long time – and we know this because we can measure historic  levels of CO2 in the atmosphere both directly (in ice cores) and indirectly (through proxies).

 

Figure 1: Global carbon cycle. Numbers represent flux of carbon dioxide in gigatons (Source: Figure 7.3, IPCC AR4).

But consider what happens when more CO2 is released from outside of the natural carbon cycle – by burning fossil fuels. Although our output of 29 gigatons of CO2 is tiny compared to the 750 gigatons moving through the carbon cycle each year, it adds up because the land and ocean cannot absorb all of the extra CO2. About 40% of this additional CO2 is absorbed. The rest remains in the atmosphere, and as a consequence, atmospheric CO2 is at its highest level in 15 to 20 million years (Tripati 2009). (A natural change of 100ppm normally takes 5,000 to 20,000 years. The recent increase of 100ppm has taken just 120 years).

Human CO2 emissions upset the natural balance of the carbon cycle. Man-made CO2 has increased  atmospheric CO2 by a third since the pre-industrial era, creating an artificial forcing of global temperatures which is warming the planet. While fossil-fuel derived CO2 is a very small component of the global carbon cycle, the extra CO2 is cumulative because the natural carbon exchange cannot absorb all the additional CO2.

The level  of atmospheric CO2 is building up, the additional CO2 is being produced by burning fossil fuels, and that build up is accelerating.

2010-08-28 02:35:29abrupt ending
nealjking

nealjking@gmail...
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There should be some kind of conclusion.
2010-08-28 06:51:05Conclusion
gpwayne
Graham Wayne
graham@gpwayne...
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Quite right. Now done...

2010-08-28 10:56:09
doug_bostrom

dbostrom@clearwire...
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Good writeup. I wonder if there's some way of emphasizing the cumulative nature of the net surplus of C02 beyond words? Maybe a graphic? You've emphasized the accumulation in the text but something w/"pop" would drive the point home.
2010-08-28 11:52:00Figure 2
John Cook

john@skepticalscience...
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I think Figure 2 is too much info - perhaps this can be moved into the Intermediate version?
2010-08-28 14:14:54Rephrasing.
villabolo

villabolo@yahoo...
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I would replace "anthropogenic" with "man made". The word "anthropogenic" could intimidate or turn off less educated persons.
2010-08-28 16:12:10Responses
gpwayne
Graham Wayne
graham@gpwayne...
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Doug: perhaps we could ask Matt the infographics guy if he could come up with something. I'll drop him a line...

John: er...I got the graphic from the intermediate - it's the GHG 'flow chart' with the complicated flows cut out. Personally, I see all these posts as an opportunity to add value to the reading experience. Surely if they want to skip the import of the graphic they can just move on, having already absorbed the main message? Anyway, I put it in as a 'counter-punch' because although we have to say the 29 Gt is small, it is also - in terms of our output of CO2, very significant. I thought by including the graphic we redressed the balance a little.

Villabolo: fair point, now addressed

2010-08-28 17:55:56Fig. 2
nealjking

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I also think this is "more than I wanted to know about penguins" for a basic-level rebuttal.

 I suggest picking one or two numbers (like the % of emissions due to energy production), and using that to "tell a story" of some sort. A table of information is like eating a pound of hamburger: unless you're really up for it, it sits in your stomach and weighs you down.

2010-08-29 00:46:00Fair enough
gpwayne
Graham Wayne
graham@gpwayne...
217.44.86.17
OK - I've removed the table. Although Neal's suggestion is a good one, I didn't really want to expand the narrative away from the main thrust of the rebuttal, so perhaps it is best removed. Without, it is punchy and to the point, which is good.
2010-08-29 00:55:59
doug_bostrom

dbostrom@clearwire...
184.77.83.151
Maybe since I suggested it I should come up with an accumulation graphic myself-- pondering on that. Meanwhile, I think the text is good, the graphic can be added once it exists.
2010-08-29 05:10:17Typo
nealjking

nealjking@gmail...
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"20.000 years." => "20,000 years."
2010-08-29 06:13:13Fixed
gpwayne
Graham Wayne
graham@gpwayne...
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thanks Neal - done.
2010-08-29 06:15:05ok
nealjking

nealjking@gmail...
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ok
2010-08-29 08:37:37Good
Andy S

skucea@telus...
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Very clear, thumbs-up from me, with one niggle:

I think that "figure 1" in the second paragraph should be "Figure 1" since it's a proper name.  

In the top line, "Pedalling myths about the carbon cycle" (my emphasis) is a pretty subtle pun. I very nearly recommended that you change the spelling to "peddling"! Obviously, you're a Guardian crossword fan.  ;-).

2010-08-29 09:21:32Small change and then I approve...
Jim Meador

jimm58@gmail...
67.101.212.216

I suggest changing...

"Man-made CO2 has increased by a third since..." 

to...

"Man-made CO2 in the air has increased by a third since..."

.and then I approve.

Good work GP! 

2010-08-29 09:27:52Comment
Robert Way

robert_way19@hotmail...
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I think that this post is nearly ready to go but I do have one minor issue. The final concluding sentence includes this statement "of annual global emissions" I think that gives the impression that exchanges in the carbon cycle are the same as emissions which is not the case. I think it would be better to say something like

"
While fossil-fuel derived CO2 is a very small component of the global carbon cycle, the extra carbon from CO2 is cumulative meaning the natural carbon exchange is not able to absorb the additional CO2. The levels of CO2 are building up, and that build up is accelerating.
"

Maybe my version isn't perfect but I think its needed to get rid of the emissions part .

2010-08-29 16:21:58Responses
gpwayne
Graham Wayne
graham@gpwayne...
217.44.86.17

Andy - small points but good none the less - now fixed.

KeepinItReal - good point, now addressed

Robert - also a good clarification, which I hope I've addresses satisfactorily.

2010-08-29 17:11:14Comment
Robert Way

robert_way19@hotmail...
142.162.188.138
I think it is good to go. Thumbs up
2010-08-29 17:42:42Carbon cycle analogies
James Wight

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Neal’s comment about “telling a story” reminded me of a couple of analogies for the carbon cycle. One is from Tim Flannery’s book The Weather Makers: he compares the carbon cycle to the Earth breathing in and out every year.

More specifically, an analogy for our disruption of the climate cycle is National Geographic’s “bathtub analogy”. If water is flowing out of the tap faster than the drain can remove it, the water level in the tub will increase.

“Man-made CO2 has increased by a third since the pre-industrial era…”
I’m not quite sure what you’re trying to say here. Humanity’s CO2 emissions have increased by something like 300,000% since 1750. The amount of CO2 in the atmosphere has increased by about 40% since 1750.
2010-08-29 18:20:11Published
John Cook

john@skepticalscience...
124.187.125.135
This one's gone live. James might have a point about "increased by a third", does this need clarifying? Feel free to tweak the text.
2010-08-29 21:46:04Tweaked!
gpwayne
Graham Wayne
graham@gpwayne...
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Thanks James and JC - a poster picked up on the same point, now fixed in both versions. 
2010-08-30 12:20:57Remember to correct both copies
James Wight

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Graham, don't forget to change it in the rebuttal as well as the blog post (unfortunately they have to be edited separately).