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Originally Posted by Cato
I'm glad you feel that way. I'm glad you like to make these definitive statements which are so easily disproved. All I need to do to disprove your statements is provide one year where the estimated anthropogenic rate of emissions could plausibly (within the rate of error) be less than the estimated rise in atmospheric CO2. In fact, I can find that information right in 2006, as you suggested:
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2006 CR = 2.33ppmv, which you've agreed could be as high as 3.33ppmv (even higher if we include the adjustment to globalize it). That equates to 26Gt CO2 (3.33 * 7.8).
HC = 6.0Gt C, which equates to 22Gt CO2 (6.0 * 3.67)
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Take any year and the figures show anthropogenic emissions higher than the rate of co2 rise in the atmosphere. That is without the error rates. I pointed out that taking a single year, or the long 250 year period has problems with accuracy (ie due to the error rate) which is why I proposed using a 10 year period.
2006 saw over 28 billion tons of co2 emissions, while co2 rose about 18 billion tons. As you pointed out it is possible these figures are inaccurate enough to mean the rise is actually more than emissions. All that requires is that the total inaccuracy brings them more than 10 billion tons closer together. So in your example you have emissions being overvalued by 20%, and co2 rise undervalued by 40%. However while I don't think this is very likely at all, I do accept it is possible. Which is why I suggested using a 10 year period in which the error range cannot "meet" co2 emissions with co2 rise. So onto that..
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The natural contribution of CO2 to the atmosphere is 4Gt. Therefore, the statements:
"The net effect is that nature removes more co2 from the atmosphere than it adds."
and...
"Without human co2 emissions the co2 levels in the atmosphere would start falling."
and...
"any time period you want to choose shows a higher anthropogenic co2 emission rate than atmospheric co2 rise"
are false. And I did it all without "human emissions [being] off by about 50%"
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I accept due to inaccuracy that for a particular year it could be possible for these not to be true, but I find it very unlikely that both figures would be off by near max error and in the right direction too.
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Equally Possible Deltas for Past 10 Years When Adjusted For Errors
1997 - 1.98
1998 - 2.83
1999 - 0.53
2000 - 2.75
2001 - 0.61
2002 - 2.83
2003 - 2.83
2004 - 0.74
2005 - 2.83
2006 - 2.83
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Yea that's fine
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Note our equation will work out to a positive natural change with any CR>=2.83ppmv.
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Ok
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Now that we have a baseline of what the possible values for each year could be, we can see what would happen to the variances if the measurements for those years were off by +/-.5ppmv.
Hypothetical CO2 Concentrations Given MLO's Deltas
Year ............. "Measured" CO2 ........... Possible CO2 ............. Variance
1997 - .................. 1.98 .................... 1.98 ......................... 0
1998 - .................. 4.93 .................... 4.81 ......................... -0.12
1999 - .................. 5.84 .................... 5.34 ......................... -0.5
2000 - .................. 7.59 .................... 8.09 ......................... 0.5
2001 - .................. 9.2 .................... 8.7 ........................... -0.5
2002 - .................. 11.75 ................. 11.53 ......................... -0.22
2003 - .................. 14.06 ................ 14.36 ......................... 0.3
2004 - .................. 15.6 ................. 15.1 .......................... -0.5
2005 - .................. 18.14 ............... 17.93 ........................ -0.21
2006 - .................. 20.47 ............... 20.76 ......................... 0.29
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Okay
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So, as you can see, part b) of our requirements is satisfied. No year varies more than +/-.5 from its "measured" amount. Using these new possible CO2 concentrations we get the new deltas posted above. Five of those years resolve to a delta of +2.83ppmv of CO2. This equates to an increase of 22.07Gt CO2 (2.83ppmv * 7.8). So, CR = 22.07.
Plugging into our formula we get:
NC = 22.07 - 22.02;
NC = .05Gt Co2;
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Okay. But have you taken the 20.76ppm rise figure you've got and applied that to 10 * 22 (10 years of 22gTC)?
20.76 * 7.8 = 162 gTC rise in atmospheric co2
10 * 22 = 220 gTC rise in human emissions
So over that 10 year period NC = 162 - 220
NC = -58
So even though nature could be a net emitter in particular years assuming a overvalue for emissions and an undervalue for co2 rise, over 10 years these errors melt away and it becomes much clearer that nature is a net sink. The yearly errors could be seen as noise on an overall trend.
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Given they take the measurements simultaneously, from the same location, I would have to assume it's a measurement error.
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Well there is natural background noise, for example co2 cycles up and down during a single year like a sine wave due to plants,seasons and temperatures. This wave is noise over the top of the rising trend, so the differences being natural variation rather than measurement error are very likely.
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Secondly, and more importantly, that's not the point. I'm not arguing there are "anthropogenic sinks". I'm arguing that, according to your source, it is possible that well over the amount of anthropogenic carbon is absorbed by nature. It's curious you argue we only need to know net natural fluxes (which you haven't been able to prove is negative), but when presented your own source's argument that the net contribution of Man's emissions could be negative you balk.
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The table isn't presenting what you think it is. Notice the second part is called
Partitioning among reservoirs. What are you partitioning? The human emissions. Therefore if you say there are only 6gTC anthropogenic emissions then you get to distribute 6 across those natural storages in the 2nd part of the table (meeting the contraint range of each one).
The items and their uncertainty ranges are not independent. "Partitioning among reservoirs" adds up to 7.1 for a reason - it's exactly what anthropogenic emissions are given as. It's not a coincidence - the basis of the table is to divide yearly anthropogenic emissions into the places it ends up going, with uncertainty ranges for individual components.
You can't, for example, set all the "Partitioning among reservoirs" items to the max of their ranges because that would give you 10.1, which is more than the max for anthropogenic emissions (8.2). That would be saying that out of 8.2 human emissions 10.1 of those emissions end up in those various places. That doesn't make sense.
As an analogy the table is like this one:
Total money given to someone: $10 (9-11)
What they did with it (ie partitioning the amount given to them):
Spent it on candy: $3 (2.5-3.5)
Gave it away: $5 (3-7)
Lost it: $2 (1-3)
Clearly you cannot take all the maximums from the last list and the minimum from the first, and say they spent $15.5 of the $9 given to them. That does not make sense.
Equally it makes no sense to say that the anthropogenic sinks took 6.6gTC of the 6gTC humans put into the atmosphere (and that would also violate the constraint that at least 3.1GtC has to be placed with the atmosphere)
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That's not true either. The table shows quite clearly that the authors have the same confidence that ALL AND MORE of the carbon from fossil fuel burning and cement production could possibly be absorbed by the ocean, forests and other terrestrial sinks:
Anthropogenic CO2 from fossil fuel burning and cement production: 5.0GtC
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They say
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Total anthropogenic emissions 7.1 (6.0-8.2)
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So if you are going to use the lower figure, its 6.0, not 5.0. But that means you have to distribute 6.0 in the "Partitioning among reservoirs" table, you cannot distribute more than the value you choose for anthropogenic emissions.
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Oceanic uptake: 2.8
Forest uptake: 1.0
Additional terrestrial sinks: 2.8
Total NON-Atmospheric storage: 6.6GtC
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You left out the Atmospheric storage:
Storage in the atmosphere 3.3 (3.1-3.5)
It has to take 3.1 of human emissions as a minimum.
Note that if you are saying humans are emitting 6.6GtC + 3.3 into the atmosphere. That's what these tables correspond to. The tables are linked, not independant. You cannot take the low end of the first and the high end of the second. The individual items are not independent. If you set ocean uptake to the high end and forest uptake to the high end then you have to "sacrifice additional terrestrial sinks" for example, you cannot set them all to max.