EPA document supports ~3% of atmospheric carbon dioxide is attributable to human sources

Bernard Lodge says:
July 29, 2014 at 6:50 am
Could someone among the many informed WUWT readers please explain how a dependent variable can also be an independent variable?
Not so difficult: it is not because one is the major driving force for the other, that the second one can’t have an influence on the first. The point is that both influences should be moderate: the combined reinforcing factors must be below unity to prevent a runaway process.
In the case of temperature and CO2, the influence of temperature on CO2 is 8 ppmv/°C as can be seen in ice cores over the past 800,000 years (Vostok, Dome C) and the MWP – LIA cooling (Law Dome DSS ice core).
The opposite influence should be – according to line by line absorption tests – about 0.9°C for 2xCO2, without taking into account any (positive or negative) feedbacks.
Both are modest influences, so it is possible that they influence each other without a runaway effect. Here a plot which shows the difference between a one-sided influence of temperature on CO2 with and without feedback from CO2 on temperature:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/feedback.jpg
The only difference is that both temperature and CO2 end somewhat higher than without influence of CO2…

“Regarding taking down this post: if you removed this post all the comments would go away.”
Not so, I’ve saved all the comments and will repost them as well, although none of them relate to the issues the lead author initially brought up and the possibly incorrect statement in the paper’s conclusion “…the 6-month average CO2ff concentrations in the lower 1 km of the atmosphere across Western Europe are between 1 to 18 ppm,” which it appears should have said “gradients” not “concentrations”.
I have been corresponding with the author via email, received a partial reply after waiting 5 days, and now am still waiting for clarification of the statement above in the conclusion prior to re-writing the post.
If the author wrote “concentrations” when she meant “gradients” and everyone wants to point fingers at the Hockey Stick for reading “concentrations” and then putting the post in draft mode until this issue is clarified by the lead author, then so be it.

“But there’s no future in arguing with the author of the study here. You’ve invoked her as the authority for your claim. She says you have grossly misinterpreted. Even if you can proved that she has worded something incorrectly or whatever, you’re never going to be able to claim her authority for the statement.”
You once again assume things that are simply not true. I am not arguing with the author at all and in fact wrote to her an apology for misunderstanding her paper, that I was temporarily taking down the post for a re-write pending her reply, and would she kindly answer a few questions to clarify prior to that re-write.
Although I still haven’t received a reply on the issue regarding her statement in the conclusion, it appears there is a significant erroneous statement in the first conclusion which conflates “concentrations” with “gradients”. If you want to blame me for quoting her conclusion in my post including this apparently incorrect conclusion in the paper, and for assuming she meant what she wrote, then so be it.
Apparently, you have an issue with a blogger reading an incorrect statement in the major conclusion of a paper, assuming it was true, but after correspondence with the author realizing she apparently made a significant incorrect statement in the conclusion, and then asking the author if this needs to be corrected. If you want to blame me for the apparent error written in the conclusion, then so be it.

To further clarify the point, the study assumes that CO2 will just keep “backing up” like water going down a drain with too much hair in it. I haven’t read the study but it sounds like there’s some assumin’ goin’ on when there needs to be some provin’ goin’ on. That’s also known as begging the question.

GeeJam, philcp, courtney, fhhaynie and hockeyschtick are correct. The EPA numbers are good enough estimates to show that human CO2 is about 3 or 4 percent of natural fluxes.
Atmospheric CO2 never “accumulates” because the enormous surface sources and sinks are constantly exchanging 30 to 40 times the anthropogenic CO2 fluxes.
Anthropogenic CO2 can never exceed the 3 to 4 percent now in the atmospheric 400 ppm, until the human flux exceeds 4 percent of the natural fluxes.
Read the fhhaynie post again. He is correct.
Also Tom V. Segalstad at http://www.co2web.info/ who knows something about CO2 isotope ratios. Also Salby, who knows something about the global biogeochemical carbon cycle.
The overwhelming amount of scientific understanding says that human contribution to the global carbon cycle has been around the 3 or 4 percent level for the last few decades.
In 1900, the human proportion of CO2 added to the atmosphere was much less. Maybe 1 percent. So the 300 ppm atmospheric CO2 was 297 ppm natural and 3 ppm anthropogenic.
in 1950 the human proportion of CO2 had risen to 2 percent. Therefore the atmospheric CO2 level of 315 ppm was about 300 ppm natural and 6 ppm anthropogenic.
In 1980 the human porportion of CO2 reached 3 percent of the natural flux. Therefore the atmospheric CO2 level of 340 ppm was 330ppm natural and 10 ppm anthropogenic.
Atmospheric CO2 is a flowing river, from sources to sinks.
The 14C bomb CO2 shows that the longer time period natural loss is 50 percent every 10 years.
50 percent of the atmospheric CO2 from 1980 was lost by 1990. By 2000 the amount of CO2 remaining in the atmosphere since 1980 was 25 percent. As of today, no more than 10 percent of the 1980 CO2 level in the atmosphere remains in the atmosphere. Thats 34 ppm of the total 1980 CO2, so the remaining 306 ppm from 1980 are “forever” gone into slower sinks.
Some CO2 does recycle, about 80 percent annually. So the amount of anthropogenic CO2 in the atmosphere today is more than 4 percent of the 400ppm at 16ppm, but certainly less than the 120 claimed by the IPCC and englebeen.

Jeremy Shiers says:
July 29, 2014 at 9:23 am
Have a play and tell us what you find
I have played with the data too, but added the δ13C derivative data to the derivatives of temperature and CO2:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/temp_dco2_d13C_mlo.jpg
If the source of the CO2 variation is by the oceans, the δ13C will go slightly up with CO2 increase, as the oceans have a higher δ13C level than the atmosphere. If it is from vegetation decay, then δ13C will go strongly down with increasing CO2 and up with falling CO2, which is the case here.
Thus the response of (tropical) vegetation on temperature variations is at work here. But vegetation is NOT the cause of the increasing trend of CO2 over the full period, as vegetation is an increasing net sink:
http://www.bowdoin.edu/~mbattle/papers_posters_and_talks/BenderGBC2005.pdf
The temperature derivative shows the same variability, but precedes the CO2/δ13C variability with pi/2, which is the result of taking the derivatives (where CO2 changes follow T changes with pi/2). Important is that there is zero trend in the temperature derivative, thus that is not the cause of the dCO2/dt slope either. But if we look at the slope of the human emissions rate of change, that slope is double that of the slope of the increase rate of CO2, simply because human emissions and increase in the atmosphere both increase slightly quadratic over time, giving a linear slope in the derivatives:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/temp_co2_acc_1900_2011.jpg
In conclusion: the match of the variability of (d)temperature and dCO2 is real, but the match of the slopes has nothing to do with temperature…

bw says:
July 29, 2014 at 1:44 pm
bw, it seems one of the most difficult points to explain to people, although most housewives (and -men) know the difference from their household budget…
What the article is about is some small addition in a large cash flow of money in and out of a factory (in the form of raw materials till finished products). Interesting, but largely irrelevant for the gain (or loss) of a business.
If you invest 10,000 euro/year in stock from a factory and the net gain of that factory at the end of each year is 5,000 euro, better sell as fast as possible and look for other opportunities, no matter if your investment is 0.1% or 10% of the capital turnover in that factory.
Turnover and gain (or loss) are quite independent items with little – if any – connection with each other.
BTW, the loss of 14C from the atomic bomb tests in the 1950’s is accelerated by the deep ocean exchanges of ~40 GtC, which release 14C depleted pre-bomb test CO2 of ~1000 years ago. That gives a decay rate of ~14 years. The real decay rate for an extra shot CO2 in the atmosphere is over 50 years:
http://www.john-daly.com/carbon.htm
Calculation from Peter Dietze already near 2 decades ago. Recent calculations give a slightly shorter decay rate.

Hockey Schtick says:
July 29, 2014 at 2:08 pm
HS, in this case concentrations at ground level are gradients compared to “background” levels.
That is the way total CO2 fluxes are calculated with tall towers, where CO2 is measured at different heights:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/cabauw_day_week.jpg

Ferdinand, your plot shows absolute concentrations at different heights and doesn’t compute or graph the “gradients” between them. Regardless, the paper under discussion is about “gradients” at the same height, not different heights, but between different surface locations, and using the term “concentrations” when you meant “gradients” is misleading/incorrect.