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Blaming nature for the CO2 rise doesn't add up

Posted on 14 August 2011 by MarkR

Recently there’s been a resurgence in claims that CO2 rise is caused by 'natural' temperature rise rather than humans. Various arguments are used to make this sound sensible (see Paolo Soares, Murry Salby and Joe Bastardi), but they’re wrong.

I’m going to pick on just one of the claims Joe Bastardi made in a comment at Tamino’s blog and this is written as an explanation to Joe of why I’m convinced he’s wrong. I hope readers will be able to point out if I’ve made a mistake and work out which argument you think makes the most sense. Bastardi claims that:

“The answer is obvious. it is the earths temperature which is driving the co2 release into the atmosphere.”

I’m going to start with chemistry; most carbon in the atmosphere is in CO2 and it can move between the atmosphere and land/oceans through chemical reactions. Billions of tons of carbon don't magically turn into pixie dust.

Next some maths: if I have one ton of carbon and I add another ton of carbon then I have two. We can write this down as an equation for the change in atmospheric CO2 over a year, ΔCatm:

This says that if I ‘emit’ a ton of carbon by, say, triggering a volcano then the atmosphere will gain a ton. If I ‘absorb’ a ton of carbon by growing a tree, then the atmosphere loses a ton.

We can expand the equation by counting human emissions (HE) and absorption (HA) and natural emissions (NE) and absorption (NA) separately.

This works because carbon is additive. If a volcano emits a ton of carbon and a factory emits a ton then the atmosphere has gained two tons. This is a very simple balance sheet for the carbon cycle and fortunately there are ‘accountants’ who’ve measured some of these values for us.

Recently the amount of CO2 in the atmosphere has been rising at ~2 parts per million per year, or around 15 billion tons/year. Meanwhile  human emissions excluding land use change (like clearing or planting forests) are 30 billion tons per year. In billions of tons per year we have:

We can rearrange this:

Humans are also clearing rainforests and changing land use, but here I'll assume that human effects on absorption (HA) are not much different from zero, i.e.

So Natural Absorption (NA) must be bigger than Natural Emissions (NE). Nature is absorbing more CO2 than it is emitting. It is not causing atmospheric CO2 to rise at all - in fact it is acting to try and reduce atmospheric CO2 and the long term rise is entirely because of humans.

Joe can demonstrate this is wrong by showing one of the following:

- Chemistry is wrong and CO2 magically disappears if humans put it into the atmosphere. Perhaps the equations should be updated with the Bastardi Pixie Dust Factor (BPDF)?:

- Addition is wrong, 1+1 does not equal 2 and 2+3 does not equal 5.

- Nature being a net absorber of CO2 from the atmosphere doesn't mean that it's taking CO2 away, and humans pumping CO2 into the atmosphere doesn't mean it's actually going into the atmosphere! Absorption is emission, emission is absorption and up is down.

- Human activity and land use changes are absorbing 30 billion tons of CO2 every year.

Or maybe, just maybe the rise in atmospheric CO2 is entirely human caused and without us CO2 levels would be much lower.

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Comments 1 to 25:

  1. What if the delta C atm (15) is fixed by temperature, or goblins, whatever. Meaning that human emission (30) determines the natural contribution: 15 = 30 + N So currently N, nature, is a sink of 15. If we cut our emissions to 0: 15 = 0 + N Then nature switches to being a source of 15. This is at least plausible on the face of it if we are just talking numbers.
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  2. wingding However it is implausble if we want to do some science where the causal mechansim must also be plausible. The problem for Salby is that the numbers don't add up for his theory. The fact that the numbers do add up for your (physically implausible) "theory" doesn't change the fact that they don't add up for Salby's. BTW anthropogenic CO2 emissions do affect natural uptake and emissions; the reason that the natural environment is currently a net carbon sink is a response to rising CO2 levels caused by anthropogenic emissions.
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  3. The linked Bastardi comment on the Tamino blog provides mainly a cut & paste job from a post on WUWT which totals about 1,000 words of nonsense. I summarise it here (still 180 words because summarising nonsense is word-intense). Bastardi says in his Tamino comment that some think him and his ilk to be right-wing idiots. I don't know his politics so I cannot say that he is. SUMMARY Only 3% to 5% of the annual increase in atmospheric CO2 rise of 1.5ppm is due to human emissions. This is small and (even if small is bad) oceans and atmosphere are big. And all the energy is in the oceans so showing the change is due to an atmospheric trace gas (has not been done &) is daunting. Contrary to climate models, satellites suggest the heat is escaping into space so CO2 sensitivity is low and model-assumed positive feedbacks are actually negative. Global warming from 1800 is said to be man-made with the assertion for 1977-98 “What else can it be?” But there was cooling since 1800, natural cooling so why not natural warming? Sunspots fit well as the driver of temperature since 1800. CO2 levels are driven by temperature as the ice core data show and so did Salby. Extreme weather events are more caused by cooling climates not warming ones. Ocean & solar cycles will cool the planet in coming decades. This will likely be obvious by 2020. If temperatures rise despite these cycles, “you carry the day.”
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  4. MA Rodger - I've drafted up a post responding to Bastardi's Gish Gallop. At least the comments he made on Fox News and Tamino's recently. We'll publish it in a couple of days. Suffice it to say, as I'm sure you're well aware, Bastardi doesn't have the slightest clue what he's talking about on any of these points.
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  5. Regarding this particular point though, I really cannot believe that so many so-called "skeptics" actually believe that CO2 is rising in response to temperature, when the argument is so easily debunked by this simple accounting approach (let alone the many other lines of evidence). Just goes to show the power of denial blinders. They seem to completely shut down critical thinking.
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  6. 1. Wingding I accept that if the change in atmospheric CO2 is being fixed by magical goblins, then human contributions don't matter. If Joe Bastardi can provide evidence to demonstrate that goblins are fixing the net CO2 flux, and hopefully explain why they only decided to start doing it at the industrial revolution and increasing it proportionally to human emissions, then I would welcome the evidence and find it fascinating.
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  7. MarkR#6: "goblins are fixing the net CO2 flux" Now that's a headline worthy of FauxNews. These are some very smart goblins (or possibly orcs). They also know that the rate of atmospheric CO2 increase must slow whenever there is a drop in annual carbon emissions. That means they knew about such things as the oil price shocks of the late 70s and even the early 90s Bush 41 recession. source Note that when the curve doubles back to the left (a decrease in annual emissions), there follows a year or two where the dots are closer together vertically (less annual change in CO2). This must mean that 'Goblins control our economy!'
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  8. Nice post Muoncounter @7, Indeed. Also, note that between 1950 and the mid seventies global temperatures declines somewhat, so how then does Salby explain the increase in CO2 of about 15 ppmv during that time. He obviously now cannot claim that the increase then was in response to the warming pulse from 1920-1945 either?
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  9. Albatross#8: "between 1950 and the mid seventies global temperatures declines somewhat, ... explain the increase in CO2" That's easy: since we know it can't be anthropogenic, both warming and cooling increase CO2. That's the power of goblin-based science: assume the answer, then manipulate the theory to produce it. QED
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  10. Ferdinand Engelbeen has three diagrams of particular interest to this debate: The first amounts to a visual presentation of the argument above: The second plots CO2 concentration against temperature anomaly: The third plots CO2 concentration against cumulative human emissions: (Note, cumulative emission, not annual emissions as shown in the graph @7) Salby and the denier cohorts are in effect asking us to ignore the 0.9966 correlation (R^2) in the third graph because they are impressed by the 0.719 correlation in the second.
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  11. TomC#10: Nice! Just to be clear, the third graph's vertical axis is the change in CO2 over the 1900 concentration. I assume the horizontal axis, showing emissions as a volume fraction has been converted from the way it is usually reported - as mass in Gtons. Hard to argue that the linear fit in the 2nd graph makes any sense whatsoever. Although it does reinforce the point that both warming and cooling must be increasing CO2, just as the goblins want us to think. They are that good!
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  12. Tom @10, Indeed. Re Fig. 17. Of course correlation is not causation, but one could argue that the increase in CO2 explains ~71% of the variance in the temperature anomaly. That is, most of the warming is attributable to human's burning fossil fuels.
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  13. It comes down to this-if, as the deniers claim, warming is causing the rise in CO2, then *what* is causing the warming in the first place? We've had 6 consecutive decades of rising temperatures & atmospheric CO2 concentrations-but over that period we've had 3 decades of stable sunspot levels, followed by 3 decades of falling sunspot levels-not to mention above average volcanic activity over the 1990's. So again I ask- "where is the warmth coming from?"
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  14. Just goes to show the power of denial blinders. They seem to completely shut down critical thinking.
    They confuse the political consequences of the study of climate change in the modern age with its scientific underpinnings. The political focus on anthropogenic global warming is a consequence of scientific inquiry, but they think the scientific focus on anthropogenic global warming is a result of political aspiration. And they think that because their own focus is politically motivated. It's no surprise they defer to ideas that get cause and effect backwards, because that is the root of their intellectual malady.
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  15. Or if their motivation is self-interest the problem is the same. Scientists want more funding for research, but they think that scientists jig their research to get more funding. Again, they superimpose their own worldview on any given subject. Reason, rather 'truth' is the first casualty in the climate wars.
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  16. The never-failing absurdity that the CO2 pollution rise is actually 'natural variation': 1. So where did all the human-generated pollution go? 2. Where did all the natural CO2 come from? 3. Instead of the 1/3-missing puzzle, there's now a 1 1/3-missing puzzle. 4. If .8dC from the 1800s drives CO2 levels up 40%, why didn't this variability ever show up in the paleo-climate proxy record? The Great CO2 Flood only shows up when the EIA is measuring massive and growing amounts of human GHG pollution. 5. 5dC from Ice Age to Interglacial had a 100ppm delta - so in the pointy-hat world, a 5dC drives a 50% rise then, but a .8dC rise drives the delta now. The problem with responding to lunatics is they have the magic spell 'budwaddabout' to avoid every defeat.
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  17. 15 owl: and that's not all. Why is the ocean acidifying? Is ocean chemistry also wrong? What about CO2 fertilisation? It reminds me of something John published a while back: scientists are saying that if it walks like a duck and quacks like a duck, it's probably a duck. Bastardi is saying that not only is something that isn't a duck walking/quacking like a duck, but someone has hidden the real duck... Or perhaps maths or chemistry are wrong.
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  18. Make it simple: Murray Salby is violating Conservation of Matter. His paper cannot possibly pass peer-review for that reason.
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  19. 2 Dikran Marsupial: "BTW anthropogenic CO2 emissions do affect natural uptake and emissions; the reason that the natural environment is currently a net carbon sink is a response to rising CO2 levels caused by anthropogenic emissions." Has there been a discussion of that point here? I assumed some mechanism must be at play, since atmos C levels have been so steady for 10^5 years, prior to the last two hundred. Is there a gas pressure equation that dictates more oceanic uptake? Is all of the 15Gt going into the oceans each year? Or is all the extra plant food making things extra lush in the tropics? :)
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  20. I'm confused. Don't denialists claim that the globe is cooling, or that - at the very least - temperatures have not increased over the past decade? If so, how come CO2 is increasing?
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  21. Crispy: re oceanic uptake, I recommend you read the "OA is not OK" article series on here - it's giving a thorough overview of how & why the oceans are taking up CO2 from the atmosphere. I also understand that some research is showing that, yes, there has been some increase in biomass in some areas, but it's small compared to the oceanic uptake. I think there are two main reason things have been relatively stable for the last 10,000 years: 1) natural climate change is quite a slow process, by human standards - the rise from the last glacial maximum, while rapid by geological timeframes, took on the order of 10,000 years, twice as long as all of recorded human history (which is ~5,000 years); 2) the natural factors that induce 'rapid' natural climate swings (~10,000 year ones!) haven't been present - the Earth's climate appears to have spent most of the past 10 millennia in a quasi-equilibrium state, although some reconstructions suggest there was a gradual cooling trend from a peak ~8,000 years ago, which we've managed to completely reverse in just 250 years (mostly in the past century, and half in the last three decades).
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  22. Crispy As far as I know there hasn't been a discussion of this specifically. The pre-indistrial carbon cycle was in a state of approximate dynamic equilibrium. The equilibrium is established by the various positive and negative feedbacks being balanced. If the system is peturbed, then the feedbacks will no longer be balanced, but in a way that tends to drive the system back to its equilibrium state. If that were not the case then the system would not have been equilibrium in the first place. In the case of the oceans, the carbon fluxes between ocean and atmosphere depend on temperature (higher temperatures -> more CO2 emission/less uptake) and the difference in partial pressures (more atmospheric CO2 -> less emissions/more uptake). So if temperatures increase, more CO2 is released from the first mechanism, but only until the resulting increase in atmospheric CO2 leads to more uptake from the second mechanism. That is why small temperature changes don't result in large CO2 emissions from the oceans. If atmospheric CO2 rises (e.g. due to anthropogenic emissions) then the additional greenhouse effect means that there is a bit more emission from the oceans, but this is dominated by the second mechansim, which reduces emissions because the greater CO2 concnetration in the atmosphere makes ocean uptake increase. I suspect the additional uptake is going into both the oceans and the terrestrial biosphere, but it will be the oceans that ultimately do most of the work, as the capacity of the deep ocean is vast, but the rate at which carbon is moved from the surface ocean to deep ocean is slow. See this paper for details.
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  23. 18. keith , I haven't seen Salby's paper so I don't know. I'll be very surprised if it matches up with Bastardi's claims. Since that means he's breaking conservation of matter and that makes me (but apparently not Bastardi, Curry or Watts) very skeptical. 19. Crispy : for a very short answer, look up Henry's Law. Global temperatures have increased by 0.3% whilst partial pressure (related to concentration) has gone up 30%. It turns out that this pressure increase is enough to put plenty of CO2 into the oceans, which accounts for some of it. Without the increase in CO2 partial pressure (thanks to fossil fuel burning), the oceans would be taking up much less.
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  24. Thanks guyz. Partial pressure, Henry's Law, Archer et al and 'OA is not OK' parts one to eleventy-seven. I have my homework.
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  25. Crispy, you may wish to add to your homeworkd Indermühle et al, 1999 which discusses variation in atmospheric CO2 over the last 10,000 years: They ascribe the 15 ppm increase in CO2 concentrations over the course of the Holocene partly to deforestation, and partly to a rise in global sea surface temperatures. Such a rise is consistent with what is known about the Holocene Climactic Optimum (and should introduce due caution about overstating its extent) in that the high temperatures 8,000 years ago where primarily a Northern Hemisphere phenomenon, while the majority of the worlds ocean surface is in the Southern Hemisphere, which has been warming over that interval. The deforestation is ascribed partly to the desertification of the Sahara, but significantly (>50%) to the introduction and spread of agriculture. In other words, a significant part of the rise in CO2 levels over that period are anthropogenic. Indermühle et al cite Bacastow, R. B. "The effect of temperature change of the warm surface waters of the oceans on atmospheric CO2" Glob. Biogeochem. Cycles 10, 319±333, (1996) and Takahashi et al, "Seasonal variation of CO2 and nutrients in the high-latitude surface oceans: A comparative study" Glob. Biogeochem. Cycles 7, 843±878 (1993), to say:
    "A change of SST by 10C causes a change in the surface ocean's CO2 partial pressure by 4.2% which translates into an atmospheric change of similar magnitude."
    That figure is consistent with the 10 ppm difference in CO2 concentration between the peak Medieval Warm Period and the minimum Little Ice Age values, for a temperature differential of just under 1 degree C, ie, consistent with various proxy reconstructions. What must puzzle anyone paying attention to the data is why, if the MWP only caused a 10 ppm excursion in CO2 concentrations, why did the only slightly warmer (to date) modern warm period cause a 120 ppm excursion in CO2 concentration (to date)?
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