Guest Post by WUWT Regular “Just The Facts” 
While the Pause in Earth’s temperature continues, currently 17 years and 10 months based upon RSS satellite data, it is important to note that Fossil Fuel and Cement CO2 emissions are at their highest levels ever.
We have been told by NASA “that carbon dioxide itself is a potent greenhouse gas (GHG)” and by NOAA’s UCAR that “the current spike in carbon dioxide is sure to result in a rapid increase in global temperature”. Anthroprogenic CO2 emissions have increased by over 60% since 1990;
and “the world added roughly 100 billion tonnes of carbon to the atmosphere between 2000 and 2010.”
“That is about a quarter of all the CO₂ put there by humanity since 1750. And yet, as James Hansen, the head of NASA’s Goddard Institute for Space Studies, observes, ‘the five-year mean global temperature has been flat for a decade.’” Economist
In order to make it easier to watch Atmospheric CO2 levels rise;
while Earth’s Temperature does not, we are pleased to introduce WUWT’s newest addition, the WUWT CO2 Reference Page. The WUWT CO2 Page offers an array of graphs on Atmospheric CO2, Anthropogenic CO2 Emissions and Land Use Change Based CO2 Estimates. In addition to the WUWT CO2 Reference Page. if you have not had the opportunity to our other Reference Pages they are highly recommended:
- Atmosphere Page
- Atmospheric Oscillation Page
- CO2 Page
- ENSO (El Nino/La Nina Southern Oscillation) Page
- “Extreme Weather” Page
- Geomagnetism Page
- Global Climate Page
- Global Temperature Page
- Great Lakes Ice Page
- Northern Polar Vortex Page
- Northern Regional Sea Ice Page
- Ocean Page
- Oceanic Oscillation Page
- Polar Vortex Page
- Paleoclimate Page
- Potential Climatic Variables Page
- Sea Ice Page
- Solar Page
- Spencer and Braswell Papers
- Tornado Page
- Tropical Cyclone Page
- US Climate Page
- US Weather Page
Please note that WUWT cannot vouch for the accuracy of the data within the Reference Pages, as WUWT is simply an aggregator. All of the data is linked from third party sources. If you have doubts about the accuracy of any of the graphs on the WUWT Reference Pages, or have any suggested additions or improvements to any of the pages, please let us know in comments below.
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dbstealey says:
August 4, 2014 at 9:23 am
That is so obviously wrong that all I can do is refer you back to the numerous charts and data that I have posted, showing that changes in CO2 are, in fact, caused by changes in T.
db, the recent increase in CO2 is not from a temperature increase. That is impossible. Warming oceans give not more than 17 ppmv/K extra CO2 in the atmosphere (Henry’s Law), warming land shows more vegetation uptake of CO2. Average 8 ppmv/K. That is all. Not 100+ ppmv for maximum 1 K increase since the LIA…
Ferdinand,
I’m still waiting for that chart…
sergeiMK says:
August 4, 2014 at 10:01 am
Nice references!
Some addition may be of interest: the1990-2000 CO2 emissions – oxygen – CO2 increase plot from Bolin:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/bolingraph.gif
Original is the Fig.3.4 in:
http://www.grida.no/climate/IPCC_tar/wg1/pdf/TAR-03.PDF
dbstealey says:
August 4, 2014 at 10:39 am
Ferdinand,
I’m still waiting for that chart…
Have a better look at:
http://www.ferdinand-engelbeen.be/klimaat/klim_img/temp_co2_acc_1900_2011.jpg
1910-1945 (35 years) warming +0,4°C; CO2 +15 ppmv
1945-1975 (30 years) cooling -0.1°C; CO2 +15 ppmv
1975-2000 (25 years) warming +0.6°C; CO2 +40 ppmv
2000-current (15 years) flat +0.0°C; CO2 +25 ppmv
At least one two periods (1045-1975 and 2000-current) where CO2 “leads” T. In fact, nothing to do with T in all these periods as the increase in CO2 is not T related but simply follows human emissions…
Hi Ferdinand,
Once again, that chart is a simple overlay. It does not show cause and effect. It does not show that CO2 ‘leads’ T. It only overlays coincidental changes.
What I am asking for is a chart like this one, which clearly shows that a change in CO2 causes a subsequent change in global temperature. I’ve been asking for someone to post such a chart for several years now, showing where ∆CO2 causes ∆T, but no one has ever produced one.
All we are left with, then, are charts showing that ∆T is the cause of ∆CO2. Now, CO2 may have a small effect on T. But if it does, that effect is too small to measure. Otherwise, you or someone else could post a chart showing that a rise in CO2 causes a rise in temperature.
But so far, there is no such evidence. Therefore, we must accept the only measurable evidence there is: CO2 reacts to temperature; not vice versa.
dbstealey says:
August 4, 2014 at 11:48 am
What I am asking for is a chart like this one, which clearly shows that a change in CO2 causes a subsequent change in global temperature.
That plot is only right for the short-term (2-3 years) variability of (tropical) vegetation and says next to nothing about the longer term variability, which is opposite to that one: vegetation is a net sink over longer term. Oceans are the main cause of long term increases.
You asked for a plot that shows that shows that CO2 changes cause T changes. My plot only shows that CO2 follows human emissions, NOT temperature, at least since 1900. If the CO2 increase causes a temperature increase remains to be seen, anyway not much and less and less the longer the current “pause” lasts…
Hello again, Ferdinand!
You write:
My plot only shows that CO2 follows human emissions…
Ferdinand, that is an OVERLAY! It doesn’t show cause and effect.
I’m still looking for a chart that shows causation, not one that shows coincidence.
The only charts I’ve ever seen show that changes in temperature cause subsequent changes in CO2. If CO2 causes changes in T, there certainly should be a chart that shows CO2 is the cause. Where is it?
dbstealey says:
August 4, 2014 at 2:30 pm
Come on db, the increase in the atmosphere almost perfectly follows human emissions, which are twice the increase in the atmosphere.
I can’t think of any natural process that will give such a 99.99% correlation that causes the same slightly quadratic increase in the atmosphere with exactly the same timing as human emissions. Certainly NOT temperature as that goes up, down, up, flat while emissions of CO2 and increase in the atmosphere are continuously increasing.
Your plot of the influence of temperature changes on CO2 changes is about a variability of +/- 1 ppmv along the trend, lasting a 1-3 years, while the trend is 100+ ppmv and human emissions were 200+ ppmv over the past 114 years…
Well, Ferdinand, if there is a cause and effect between the rise in CO2 and the rise in temperature, you should be able to find a chart like this showing that T follows CO2.
But if all you have are overlays of CO2 and temperature charts, then maybe your conjecture is base on a simple coincidence. In science, stranger things have happened.
I’m willing to be educated, and you are good at it. But I need that chart to be convinced. Play around with the WoodForTrees site, maybe you can find something. So far, I haven’t been able to. Everything I’ve found shows that CO2 follows T.
Geejam
“The amount of CO2 is approximately double of that if the grapes had just been left to naturally rot on the vines and return to the soil”
Actually you produce 3 times more CO2 in making wine than just let the grapes rot.
Decomposition of glucose
C6H12O6 –> 6 CO2 + 6 H2O
Fermentation of glucose to ethanol (liquor)
C6H12O6 –> 2 C5H5OH + 2 CO2
“If it were the same amount of CO2, I will never need to purchase alcohol again – just eat rotting fruit.”
You can eat rotten fruits but you will not get drunk with water.
The wheat and yeast in your bread get their CO2 from the air and will return to the air.
“not all man-made bottled (or liquid) CO2 for industrial processes derives from natural gas. It can be made from hydrogen and ammonia reaction using methane produced during industrial biomass processes for example”
Chemically possible but that’s not how we produce industrial CO2. We can also make hydrogen gas from seawater but we make it from natural gas because it’s cheaper.
Correction: 3 times more CO2 in rotting grapes than in wine making.
Sorry, the balanced chemical equation is:
Decomposition of glucose
C6H12O6 + 6 O2 –> 6 CO2 + 6 H2O
The conclusion is correct: 3 times more CO2 in rotting grapes than in wine making.
My chemistry is bad today. The balanced chemical equation is:
Fermentation of glucose to ethanol (liquor)
C6H12O6 –> 2 C2H5OH + 2 CO2
Same conclusion: 3 times more CO2 in rotting grapes than in wine making
dbstealey says:
August 4, 2014 at 4:36 pm
Everything I’ve found shows that CO2 follows T.
Check this out. CO2 has absolutely nothing to do with T, but everything to do with human emissions.
http://www.woodfortrees.org/plot/hadcrut4gl/from:1958/to:1977/plot/hadcrut4gl/from:1958/to:1977/trend/plot/esrl-co2/from:1958/to:1977/normalise/plot/esrl-co2/from:1958/to:1977/normalise/trend
You have posted a great many graphs supporting your point of view, and I agree with virtually all, however if you expect others to accept the obvious truths in your graphs, I would think that you would also accept the obvious truth in the above graph. What you say applied thousands of years ago with respect to CO2 and T, but not since 1900. I agree 100% with Ferdinand here. I am well aware of the fact that others do not agree, however I remain unconvinced by the arguments of the others.
Werner says:
What you say applied thousands of years ago with respect to CO2 and T, but not since 1900.
This graph is recent. So is this one. And this one is also “since 1900“. How do you explain those? Don’t they contradict your statement?
All I want is a similar chart, but one that shows CO2 controlling T.
Still waiting for someone to post such a chart.
dbstealey says:
August 5, 2014 at 12:50 am
db, your graphs are about the short term variability of +/- 1 ppmv: peanuts in the 70+ ppmv increase since 1959. Indeed caused by temperature variations, but T has nothing to do with the 70+ ppmv increase in the atmosphere.
You are asking for the reverse chart: there is none, but you are wrong too: our charts show that T is not the cause of the recent rise in CO2, while you still defend that…
Ferdinand Engelbeen.
Your claim about human CO2 production is based on unfounded claims by the IPCC. The US Energy department put it at 3% of total production. But even that figure is based partly on guesswork. We actually do not know. it has been discovered that CO2 produced by FF use is isotopically identical to volcanogenic CO2. So there is no way to differentiate. NASA has also calculated that the Oceans top the CO2 producer list with insects and volcanoes in the list above human FF produced.
johnmarshall says:
August 5, 2014 at 3:43 am
John, we have been there before: isotopic composition of FF is quite different from volcanic or oceanic releases, but the same as for vegetation. But the latter is a proven sink for CO2.
That the human CO2 production is only 3% (or 1% or 10%) is not relevant: that is 3% of the inputs, but only 1.5% of the outputs. The difference is what remains in the atmosphere. Not the huge natural inputs and outputs, as these (near) balance each other: slightly more output than input…
dbstealey says:
August 5, 2014 at 12:50 am
This graph is recent. So is this one. And this one is also “since 1900“. How do you explain those? Don’t they contradict your statement?
I find the first one confusing since CO2 does not go up since 1980 and no one argues that it did not. So whatever they are trying to show, I do not accept it. Furthermore, the second line in the top graph says: “Since 1980, global temperature change is not being caused by human CO2 emissions”. That is totally different than saying “Since 1980, global CO2 change is not being caused by human CO2 emissions”.
As for your last two, take the slopes of each. I did that for the last one and CO2 goes up but temperature goes down. That agrees with what I showed before. See:
http://www.woodfortrees.org/plot/esrl-co2/isolate:60/mean:12/scale:0.26/plot/hadcrut3vgl/isolate:60/mean:12/from:1958/plot/esrl-co2/isolate:60/mean:12/scale:0.26/trend/plot/hadcrut3vgl/isolate:60/mean:12/from:1958/trend
By the way, it is obvious Lord Monckton agrees with Ferdinand with this quote:
Monckton corrected me with
“Steve Oregon” is incorrect to say that man-made CO2 is little more than 3% of atmospheric CO2. It is more like 40%.”
Ferdinand and Werner,
Ferdinand says:
…your graphs are about the short term variability…
OK then, here is a graph with a much longer time frame. Here is another one.
I am not disputing your chart, Werner. But it is not an adequate explanation by itself. I also agree with Ferdinand that human CO2 emissions are the reason for the recent rise in atmospheric CO2. But that isn’t my point, and it never has been. I’ve always agreed with that, ever since Ferdinand provided convincing evidence.
My point is this: if a rise in CO2 is the cause of a subsequent rise in global T, then where is the evidence? That should be readily available in the form of a chart, just like the other charts I posted are. <—[that chart is clear, unambiguous, empirical evidence showing conclusively that ∆T is the cause of ∆CO2].
But where is a comparable chart showing what you claim? A chart showing that ∆CO2 causes ∆T? The fact that no one can produce such a chart means that there probably is no such evidence available.
If there is no evidence to show that ∆CO2 causes ∆T, then that is nothing more than a conjecture. An opinion. An evidence-free assumption.
I have no problem at all accepting what you assume. But in order to move beyond a conjecture, you must produce testable, measurable scientific evidence. But so far, there is no such evidence.
Has it ever occurred to you that however much sense your conjecture makes, it might possibly be wrong? The history of science is filled with examples of beliefs that were later overturned. The only defense against that is an open mind. My mind is open. Please fill it with evidence.
dbstealey says:
August 5, 2014 at 9:42 am
I also agree with Ferdinand that human CO2 emissions are the reason for the recent rise in atmospheric CO2. But that isn’t my point, and it never has been.
Somehow I got the impression you did not accept this. But since you do and agree with us here, that is good. ☺
Thank you, Werner.
I agree with you on that point. But on the question of which is the cause, and which is the effect, no one has posted any evidence showing that ∆CO2 causes a subsequent change in temperature. The only cause and effect evidence shows that changes in CO2 are caused by changes in T.
That tells me that the alarmist crowd got causality wrong. They got it backward. So of course their conclusion will be wrong.
I can be convinced that I am wrong very easily: just produce a verifiable, testable chart showing that changes in temperature are preceded by changes in CO2; the same kind of WFT chart that you posted in your last comment. That should be very simple to do… IF CO2 is the cause of ∆T.
But absent such evidence, I remain skeptical.
dbstealey says:
August 6, 2014 at 2:54 pm
The only cause and effect evidence shows that changes in CO2 are caused by changes in T.
But you also agree with the following: “Changes in CO2 are also caused by changes in human contributions.”
I have no interest in getting into semantics as to whether or not you accept that human contributions are also a “cause” and higher CO2 is an “effect”.
I obviously misinterpreted your statement: “The only cause and effect….” to mean that you believed humans had no influence. But that has been cleared up now. Thanks! ☺
Werner says:
But you also agree with the following: “Changes in CO2 are also caused by changes in human contributions.”
Yes, I agree. But that is entirely different from the statement: ‘changes in CO2 are caused by changes in tempearture, but there is no testable, measurable scientific evidence showing that changes in temperature are caused by changes in CO2′.
Human activity has caused a rise in atmospheric CO2, from 0.03% to 0.04%. However, global warming has not followed that rise for more than seventeen years now, per the satellite record [or ten years±, if you use GISS or other ‘adjusted’ data].
Do you see the difference? I’m sure you must. You are smarter than most.
Ferdinand also sees the difference. He’s no dummy, either. But he has quietly abandoned this debate, because he cannot produce the causation chart I’ve repeatedly requested.
So I ask you, Werner, just like I asked Ferdinand: could it possibly be that you’re mistaken about the effect of CO2? All it would take to convince me is a WoodForTrees chart, showing that ∆CO2 is the cause of ∆T. Not just once, or sporadically, but consistently over different time scales, like the charts I constantly post showing conclusively that ∆T is the cause of ∆CO2.
This question goes to the heart of the AGW debate. Without measurements, there is no science. Surely you know that better than most. So, convince me. Produce a chart showing the claimed causation; a chart showing that changes in CO2 are the cause of subsequent changes in temperature, on a global scale. At this point, I’ll accept just about any chart you post, if it shows that causation.
dbstealey says on August 6, 2014 at 8:23 pm
Hello db:
Thank you for your post and your graph of atmospheric CO2 lagging “global” temperature T by about 800 years over a time scale of several hundred thousand years of recent Earth history.
As you know, CO2 also lags T in the modern data record by about 9 months, on a shorter time cycle.
It appears that CO2 lags T at all measured time scales. This still allows for other significant drivers of atmospheric CO2, such as fossil fuel combustion, land-use changes such as deforestation, ocean outgassing, etc.
There is reluctance of most parties on both sides of the “mainstream” climate debate to discuss the “CO2 lags T” issue. The mainstream climate debate is essentially an argument about the magnitude of equilibrium climate sensitivity or ECS: Warmists say ECS>= 3C or more, which is nonsense; Skeptics say ECS,<= 1C, which is more reasonable but still questionable, in my opinion.
I suspect this general reluctance to discuss “CO2 lags T” is a fear of being ridiculed or marginalized. However I suggest it is at the very core of the “catastrophic humanmade global warming” (CAGW) issue.
For example, the concept of ECS must ASSUME that CO2 drives T, but does ECS really exist is any physical sense?
What are the alternatives:
A) Maybe ECS does not exist at all in physical reality, and we should be discussing the sensitivity of atmospheric CO2 to temperature (let’s call it EC02S).
B) Maybe ECS co-exists along with ECO2S in physical reality:
B1) In this scenario can we conclude that ECO2S exceeds ECS since that is the only signal we can detect in the modern data record; or
B2) Is it possible that ECS exceeds ECO2S but exists on a fuzzy longer time scale that is difficult to detect in the modern data record?
C) Maybe, as was strongly suggested in 2008, ECO2S is a “spurious correlation”. I suggest this notion is no longer considered valid and the correlation is real and significant.
Comments anyone?
Regards to all, Allan
__________
Here is some history compiled over recent years on this subject:
To my knowledge, I initiated in early January 2008 the still-heretical notion that dCO2/dt changed ~contemporaneously with temperature and therefore CO2 lagged temperature by about 9 months, and thus CO2 could not primarily drive temperature.
http://icecap.us/index.php/go/joes-blog/carbon_dioxide_in_not_the_primary_cause_of_global_warming_the_future_can_no/
I later learned from Richard Courtney that others (Kuo et al 1990, Keeling et al 1995) had noted the lag but apparently not the dCO2/dt relationship with T. Roy Spencer was kind enough to acknowledge my contribution at
http://wattsupwiththat.com/2008/01/25/double-whammy-friday-roy-spencer-on-how-oceans-are-driving-co2/
I am fairly sure this concept was new because of the very hostile reaction it received from BOTH sides of the CAGW debate. All the warmists and most skeptics completely rejected it.
First I was just plain wrong – the dCO2/dt vs T relationship was merely a “spurious correlation”.
Then I was grudgingly admitted to be correct, but the resulting ~9 month CO2-after-T lag was dismissed as a “feedback effect”. This remains the counter-argument of the global warming alarmists, apparently the best they’ve got – a faith-based “Cargo Cult” rationalization, in my opinion.
Now we are embroiled in the “Mass Balance Argument” as ably debated by Ferdinand Engelbeen and Richard S Courtney, and I frankly think this is quite worthwhile. To me, this is the cutting edge of climate science, and it is interesting.
I also infer that some parties, notably Jan Veizer at the University of Ottawa, had gotten almost this far some time ago.
Intellectually, I think the alleged global warming crisis is dead in the water, although politically it sails on, a ghost ship with the Euros and Obama at the helm. Not to forget our own Dalton McGuinty in Ontario – now a “have-not province” collecting transfer payments , our national welfare scheme for mismanaged economies.
The global warming alarmists have squandered more than a trillion dollars of scarce global resources on foolish “alternative energy” schemes that we condemned in writing in 2002. We said then that “the wasteful, inefficient energy solutions proposed by Kyoto advocates simply cannot replace fossil fuels” and this is now proven to be true. The economies of the European countries and their fellow-travellers have been hobbled by green energy nonsense, and millions are suffering and thousands are dying each winter from excessively high energy costs.
I am concerned, I hope incorrectly, about imminent global cooling, which I (we) also predicted in a Calgary Herald article in 2002. I really hope to be wrong about this prediction, because global cooling could cause great suffering. Our society has been so obsessed with the non-existent global warming crisis that we are woefully unprepared for any severe global cooling, like the Maunder or Dalton Minimums circa 1700 and 1800.
Solar activity has crashed in SC24, and although our friend Leif Svalgaard says not to worry, I continue to do so.
_________
My paper was posted Jan.31/08 with a spreadsheet at
http://icecap.us/index.php/go/joes-blog/carbon_dioxide_in_not_the_primary_cause_of_global_warming_the_future_can_no/
The paper is located at
http://icecap.us/images/uploads/CO2vsTMacRae.pdf
The relevant spreadsheet is
http://icecap.us/images/uploads/CO2vsTMacRaeFig5b.xls
There are many correlations calculated in the spreadsheet.
In my Figure 1 and 2, global dCO2/dt closely coincides with global Lower Tropospheric Temperature LT and Surface Temperature ST. I believe that the temperature and CO2 datasets are collected completely independently, and yet there is this clear correlation.
After publishing this paper, I also demonstrated the same correlation with different datasets – using Mauna Loa CO2 and Hadcrut3 ST going back to 1958. Later I examined the close correlation of LT measurements taken by satellite and those taken by radiosonde.
Further, earlier papers by Kuo (1990) and Keeling (1995) discussed the delay of CO2 after temperature, although neither appeared to notice the even closer correlation of dCO2/dt with temperature. This correlation is noted in my Figures 3 and 4.
See also Roy Spencer's (U of Alabama, Huntsville) take on this subject at
http://wattsupwiththat.wordpress.com/2008/01/25/double-whammy-friday-roy-spencer-on-how-oceans-are-driving-co2/
and
http://wattsupwiththat.wordpress.com/2008/01/28/spencer-pt2-more-co2-peculiarities-the-c13c12-isotope-ratio/
This subject has generated much discussion among serious scientists, and this discussion continues. Almost no one doubts the dCO2/dt versus LT (and ST) correlation. Some go so far as to say that humankind is not even the primary cause of the current increase in atmospheric CO2 – that it is natural. Others rely on a "material balance argument" to refute this claim – I think these would be in the majority. I am (almost) an agnostic on this question, to date.
The warmist side also has also noted this ~9 month delay, but try to explain it as a "feedback effect" – this argument seems more consistent with CAGW religious dogma than with science ("ASSUMING CAGW is true, then it MUST be feedback"). 🙂
It is interesting to note, however, that the natural seasonal variation in atmospheric CO2 ranges up to ~16ppm in the far North, whereas the annual increase in atmospheric CO2 is only ~2ppm. This reality tends to weaken the "material balance argument", imo. This seasonal 'sawtooth" of CO2 is primarily driven by the Northern Hemisphere landmass, which is much greater in area than that of the Southern Hemisphere. CO2 falls during the NH summer due primarily to land-based photosynthesis, and rises in the late fall, winter and early spring as biomass degrades.
There is also likely to be significant CO2 solution and exsolution from the oceans.
See the excellent animation at http://svs.gsfc.nasa.gov/vis/a000000/a003500/a003562/carbonDioxideSequence2002_2008_at15fps.mp4
It is also interesting to note that the detailed signals we derive from the data show that CO2 lags temperature at all time scales, from the 9 month delay for ~ENSO cycles to the ~800 year delay inferred in the ice core data for much longer cycles.
__________
In this enormous CO2 equation, the only signal that is apparent is that dCO2/dt varies ~contemporaneously with temperature, and CO2 lags global Lower Troposphere temperatures by about 9 months.
CO2 also lags temperature by about 800 years in the ice core record on a longer time scale.
I suggest with some confidence that the future cannot cause the past.
I suggest that temperature drives CO2 more than CO2 drives temperature. This does not preclude other drivers of CO2 such as fossil fuel combustion, deforestation, etc.
My January 2008 hypo is gaining traction with the recent work of several researchers. We don’t always agree on the fine details, but there is clear agreement in the primary hypothesis.
Here is Murry Salby's address to the Sydney Institute in 2011:
Here is Salby’s address in Hamburg 2013:
See also this January 2013 paper from Norwegian researchers:
The Phase Relation between Atmospheric Carbon Dioxide and Global Temperature
Global and Planetary Change
Volume 100, January 2013, Pages 51–69
by Ole Humluma, Kjell Stordahlc, Jan-Erik Solheimd
http://www.sciencedirect.com/science/article/pii/S0921818112001658
Highlights
– Changes in global atmospheric CO2 are lagging 11–12 months behind changes in global sea surface temperature.
– Changes in global atmospheric CO2 are lagging 9.5–10 months behind changes in global air surface temperature.
– Changes in global atmospheric CO2 are lagging about 9 months behind changes in global lower troposphere temperature.
– Changes in ocean temperatures explain a substantial part of the observed changes in atmospheric CO2 since January 1980.
– Changes in atmospheric CO2 are not tracking changes in human emissions.
A paper by a group from three Dutch universities published in Atmospheric Chemistry and Physics that they have found that only about 3.75% [15 ppm] of the CO2 in the lower atmosphere is man-made from the burning of fossil fuels, and thus, the vast remainder of the 400 ppm atmospheric CO2 is from land-use changes and natural sources such as ocean outgassing and plant respiration.
http://www.atmos-chem-phys.net/14/7273/2014/acp-14-7273-2014.html
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