# The CO2 concentration graph: Guesses solicited for its future shape and consequences

**URL:** <https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391>\
**Category:** Great Debates\
**Created:** [August 14, 2009, 11:27am UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391 "2009-08-14T11:27:28Z")\
**Posts on this page:** 20\
**Page:** 3

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**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\
**Post date:** [August 20, 2009, 7:08am UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/41 "2009-08-20T07:08:09Z")

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> [@Quartz](#):
>
> No. There’ve been a normal number of sunspots. Now there aren’t. We’ll have to wait and see what effect this has.

Check the graph please, the correlation is not there anymore since 1975; if it was the sun, then the reduction in activity should had led to a reduction in temperature.

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**Author:** ![SentientMeat](https://avatars.discourse-cdn.com/v4/letter/s/43a26b/32.png) [@SentientMeat](https://boards.straightdope.com/u/SentientMeat)\
**Post date:** [August 20, 2009, 7:59am UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/42 "2009-08-20T07:59:19Z")

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> [@intention](#):
>
> Well, my guess would be that it’s because I hadn’t gotten around to reading it yet, so please re-insert your snark into your fundamental orifice.

**intention** , thanks for dropping by. Your guesses for A) and B), however vague, would be most welcome.

> [@](#):
>
> On an more practical note, what temperature record are you planning to use for this bet with Chief Pedant? Satellite? Which one? Terrestrial? Which one?

A combination of land and marine data following the method prescribed in [this paper](http://www.agu.org/pubs/crossref/2006/2005JD006548.shtml). However, a new record temperature would be headline news on any international news site - if **CP** had any reason to doubt such reports, he could bring them up himself. Would _you_ like to take the side bet, given your “Global Warming stopped 10 years ago” spiel?

> [@](#):
>
> PS - as has been repeatedly pointed out, “Deniers” is an insult. It is a pathetic, puerile attempt to equate people who happen to disagree with you with people who deny the Holocaust. Attempting to insult those who oppose you only reveals the weakness of your position. If I were to call AGW supporters say “Sheep”, you would be equally insulted, which is why I don’t do that. Please re-insert the term “Deniers” into the aforementioned location as well, it is not conducive to scientific discussion.

Oh, please. If someone _denies_ AGW, AGW Deniers is a perfectly reasonable epithet. And you should note that historical revisionists have largely taken to calling themselves “Holocaust _skeptics_” these days, but I’ll call you guys AGW skeptics if you like. I’m happy for you to label AGW-accepters “sheep” if it means you’ll actually engage with the debate set out in the OP.

> [@billfish](#):
>
> If you folks want data that IMO is least likely to be wrong measurement wise, look for data on permafrost temperature profiles.

What? Why would anyone choose a mere _local_ measurement in place of a _global_ one to measure _global temperature_?? This is a sadly typical tactic by which you guys avoid the direct questions asked in my OP. ([del]If I were to take the bait, I’d show you some [data from Fairbanks](http://www.arctic.noaa.gov/essay_romanovsky.html) showing a clear overal warming trend, but instead I’ll let this frozen red herring melt away until it doesn’t smell so fishy[/del].)

> [@Quartz](#):
>
> further warming while there’s a continued lack of sunspots will falsify this theory. I would suggest that it will take at least 1 11-year cycle.

**Quartz** , that’s a very honest and reasonable engagement on your part - many thanks.  
**jshore** , what would this place do without you?

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**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\
**Post date:** [August 20, 2009, 9:21am UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/43 "2009-08-20T09:21:02Z")

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> [@GIGObuster](#):
>
> Check the graph please, the correlation is not there anymore since 1975; if it was the sun, then the reduction in activity should had led to a reduction in temperature.

Why don’t you check the graph? It’s measuring total solar radiance; I’m talking about sunspots.

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**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\
**Post date:** [August 20, 2009, 9:50am UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/44 "2009-08-20T09:50:47Z")

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I missed the edit period, but somehow my comment that the issue of sunspot numbers is dealt with in the comments got deleted.

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**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\
**Post date:** [August 20, 2009, 9:57am UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/45 "2009-08-20T09:57:20Z")

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> [@SentientMeat](#):
>
> **Quartz** , that’s a very honest and reasonable engagement on your part - many thanks.

My pleasure. But realise that thanks to the oceanic lag we’re not going to know for at least two decades even if there continue to be no sunspots. We should not wait but continue to research all reasonable hypotheses. In particular, we should work to find a falsification test for the CO2 theory. Just because I’m sceptical of the theory doesn’t mean I don’t think it’s worth further investigation!

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**Author:** ![SentientMeat](https://avatars.discourse-cdn.com/v4/letter/s/43a26b/32.png) [@SentientMeat](https://boards.straightdope.com/u/SentientMeat)\
**Post date:** [August 20, 2009, 10:06am UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/46 "2009-08-20T10:06:08Z")

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> [@Quartz](#):
>
> In particular, we should work to find a falsification test for the CO2 theory.

But that’s easy peasy: CO2 is increasing rapidly. If temperatures show a consistent dip _at all_ over, say, the next 7 years, it will be falsified.

> [@](#):
>
> Just because I’m sceptical of the theory doesn’t mean I don’t think it’s worth further investigation!

Might I ask, _why_ are you sceptical of the theory that a large increase in the concentration of IR-absorbing gases might, you know, _absorb enough IR to cause a rise in temperature_? I asked you this before, but missed your answer: if we _removed_ lots of IR absirbing gas from the atmosphere, are you sceptical that the world would get _colder_? That is, are you sceptical of _the Greenhouse Effect itself_?

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**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\
**Post date:** [August 20, 2009, 11:14am UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/47 "2009-08-20T11:14:06Z")

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> [@SentientMeat](#):
>
> For info, the level stayed roughly constant at 280 ppmv for millennia before the Industrial Revolution)

No, it didn’t.

Have a look at the [Law Dome data](http://www-das.uwyo.edu/~geerts/cwx/notes/chap01/icecore.html). In 1650, the height of the little Ice Age, the concentration was ~270ppm. By 1700, well before the industrial revolution, it was ~285ppm.

The fact is that carbon dioxide levels started to rise in ~1600, and the increase has held to an almost perfect [exponential curve ever since](http://leam-calculus.activemath.org/ActiveMath2/LeAM_calculusPics/ExponentialR.png?lang=en). Anyone in 1900 could have predicted this trend based on the past 300 years data simply by extrapolating an exponential continuation of the existing trend.

Moreover this is a trend that we see repeated regularly [over the past half million years](http://www.lpi.usra.edu/education/explore/ice/background/images/cycles.jpg). The carbon dioxide level drops and then surges upwards in an exponential increase. The pattern is incredibly regular and incredibly similar to what we see today.

But, you say, the past maxima were only ever 300 ppm, while the current maximum is ~100ppm higher than that.

Well, no, that isn’t true.

The current levels of \>300ppm have only been recorded for less than 50 years. The ice cores currently used to measure the past levels have intrinsic limitations for short term fluctuations because the gas trapped in the ice is much younger than the ice itself. So we can’t really get an accurate handle on whether short term spikes in CO2 concentration (\<80 years) occurred in the past by using ice cores simply because the very mechanism of gas deposition smooths out short term fluctuations of less than 80 years, and may smooth out even longer trends.

When we look at using methods other than ice cores we find that short term fluctuations in both temperature and CO2 levels are much higher than the ice cores suggest. For example:

“…past (temperature) variations may have been at least a factor of 2 larger than indicated by empirical reconstructions.”  
von Storch et al. 2004 “Reconstructing Past Climate from Noisy Data“ Science 306

‘‘The majority of the stomatal frequency-based estimates of CO 2 for the Holocene do not support the widely accepted concept of comparably stable CO2 concentrations throughout the past 11,500 years.”  
Wagner et al 2009 “Reproducibility of Holocene atmospheric CO2 records based on stomatal frequency” Quaternary Science Reviews 23  
“Data from ice cores suggest that Late-glacial and early Holocene atmospheric CO2 variations were rather conservative, the most important change being a gradual Younger Dryas increase. By contrast, palaeo-CO2 records based on the inverse relationship between CO2 partial pressure and stomatal frequency of terrestrial plant leaves reflect a more dynamic CO2 evolution”

Rundgren et al 2003 “Late-glacial and early Holocene variations in atmospheric CO2 concentration indicated by high-resolution stomatal index data” Earth and Planetary Science Letters 213

“presently available paleoclimatic reconstructions are inadequate for making specific inferences, at hemispheric scales, about MWP warmth relative to the present anthropogenic period and that such comparisons can only still be made at the local/regional scale.”  
Rosanne D’Arrigo 2006 “On the long-term context for late twentieth century warming” JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111  
So I totally reject your claim that “the level stayed roughly constant at 280 ppmv for millennia before the Industrial Revolution”, as do numerous other scientists. It only appears to remain stable if you use ice core data, which are known to smooth short term trends, or very restricted dendrochronological data. If you use other proxies such as speleotherms, stomatal data or even broader dendrochronological data the CO2 concentrations are every bit as dynamic as the recent fluctuations.

So based on the fact that CO2 concentrations have demonstrably _NOT_ been stable for millennia, I really don’t see much to explain in this graph. The CO2 trace is following almost exactly the same trend that it has followed multiple times in the past. I see no compelling reason to believe the current levels are greatly higher than in the past. Somewhat higher, I’m sure, but there’s no evidence that the current trend hasn’t been repeated multiple times in the past half million years.

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**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\
**Post date:** [August 20, 2009, 11:24am UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/48 "2009-08-20T11:24:15Z")

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> [@SentientMeat](#):
>
> But that’s easy peasy: CO2 is increasing rapidly. If temperatures show a consistent dip _at all_ over, say, the next 7 years, it will be falsified.

But [global temperature](http://odin.physastro.mnsu.edu/~eskridge/astr102/atmos_temp.gif) showed a consistent dip from 1945 to 1975, and CO2 was increasing rapidly then too. So why doesn’t that falsify the theory?

And the answer is that we then incorporated aerosols into the model to allow for the dip.

So I see no reason why a consistent dip from 2010 to to 2007 would be any more likely to falsify this theory than the 1945-1975 dip. Why wouldn’t the AGW patsies simply incorporate yet another variable inopt the model to allow them to cling to the theory despite the fact that temperature and CO2 levels move in opposite directions for a few decades?

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**Author:** ![SentientMeat](https://avatars.discourse-cdn.com/v4/letter/s/43a26b/32.png) [@SentientMeat](https://boards.straightdope.com/u/SentientMeat)\
**Post date:** [August 20, 2009, 12:18pm UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/49 "2009-08-20T12:18:54Z")

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> [@Blake](#):
>
> Have a look at the Law Dome data. In 1650, the height of the little Ice Age, the concentration was ~270ppm. By 1700, well before the industrial revolution, it was ~285ppm.

And you wouldn’t call this _roughly_ constant at _around_ 280ppmv? Christ …

> [@](#):
>
> The current levels of \>300ppm have only been recorded for less than 50 years. The ice cores currently used to measure the past levels have intrinsic limitations for short term fluctuations because the gas trapped in the ice is much younger than the ice itself. So we can’t really get an accurate handle on whether short term spikes in CO2 concentration (\<80 years) occurred in the past by using ice cores simply because the very mechanism of gas deposition smooths out short term fluctuations of less than 80 years, and may smooth out even longer trends.  
> …If you use other proxies such as speleotherms, stomatal data or even broader dendrochronological data the CO2 concentrations are every bit as dynamic as the recent fluctuations.  
> …  
> So based on the fact that CO2 concentrations have demonstrably NOT been stable for millennia, I really don’t see much to explain in this graph. The CO2 trace is following almost exactly the same trend that it has followed multiple times in the past. I see no compelling reason to believe the current levels are greatly higher than in the past. Somewhat higher, I’m sure, but there’s no evidence that the current trend hasn’t been repeated multiple times in the past half million years.

Just to clarify, are you suggesting that the \>300ppm concentrations of the last decades have nothing to do with humans digging up _vast_ quantities of carbon stores and burning them? I might be willing to accept that a brief spike caused by, say, a huge volcanic eruption might have been rounded off by the mechanism you propose, but there _hasn’t been one recently_. Whatever the “true” levels in the past million years, the system was clearly in _equilibrium_ in the longer term. How are the demonstrably vast human emissions _not_ a clear departure from this natural equilibrium?

> [@](#):
>
> Why wouldn’t the AGW patsies simply incorporate yet another variable [into] the model to allow them to cling to the theory despite the fact that temperature and CO2 levels move in opposite directions for a few decades?

Well, _this_ patsy won’t - how’s that? Fancy taking the bet?

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**Author:** ![SentientMeat](https://avatars.discourse-cdn.com/v4/letter/s/43a26b/32.png) [@SentientMeat](https://boards.straightdope.com/u/SentientMeat)\
**Post date:** [August 20, 2009, 12:34pm UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/50 "2009-08-20T12:34:20Z")

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And **Blake** , might I enjoin you to share your vague guess as to what will happen to the CO2 graph over the next, say, two centuries, and the consequences thereof?

It seems like you’re willing to accept a level-off of 600+ ppmv, but unwilling to lay such a level at the door of humanity’s predeliction for burning Gigatons of hydrocarbons every year. Even if, for argument’s sake, a significant proportion of the extra 1.7 ppmv of CO2 we’re measuring every year comes from natural sources (and I frankly don’t really see how that’s the case), surely it would be wise to, you know, stop _adding_ to it so much?

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**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\
**Post date:** [August 20, 2009, 1:48pm UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/51 "2009-08-20T13:48:02Z")

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[QUOTE=SentientMeat;11464509  
What? Why would anyone choose a mere _local_ measurement in place of a _global_ one to measure _global temperature_?? This is a sadly typical tactic by which you guys avoid the direct questions asked in my OP. ([del]  
If I were to take the bait, I’d show you some [data from Fairbanks](http://www.arctic.noaa.gov/essay_romanovsky.html) showing a clear overal warming trend, but instead I’ll let this frozen red herring melt away until it doesn’t smell so fishy[/del].)  
**Quartz** , that’s a very honest and reasonable engagement on your part - many thanks.  
?  
[/QUOTE]

WHO put an an icicle up your rear?

I suggested those measurement for several reasons. I did a little work for the guy doing them way back when. They don’t have some of the problems other measurements do (like the possible “city” effect for air temp measurements). They are VERY precise (IIRC something like a thousandth of a degree). They contain short term, medium term, and long term temp data. The sites are usually out in Middleofnowherestan, surrrounded by thousands of miles Pristinewildernessstan  
so you don’t have the problem of very local and man cause environmental changes.

I have no idea whether they even show a warming or a cooling. I 've never actually even LOOKED at the data. Hell, for all I know the guy working on those (though I doubt he was the only one) died a decade or two ago. I do know that particular researcher wasnt working off just one site.

I brought it up because I’ve never seen that data mentioned here. Is it because they have figured it doesnt really work? Is it because it hasnt been warming for long enough or warm enough for it to show in that data yet? Or is it because you don’t like the fact that it isnt actually showing a warming? Again, I have no idea either way.

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**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\
**Post date:** [August 20, 2009, 1:59pm UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/52 "2009-08-20T13:59:49Z")

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Oh, yeah, forgot to give input on the OP:  
A) I’d say steadily _accelerating_ increase to _at least_ 600ppm, and no, I don’t think there’s enough international will to do anything about it until at least that point, plus…lag effects.  
B) Pretty bad for a lot of coastal places, complete disappearance of summer Arctic ice every year, losses of entire ice fields in Antarctica, sea level rise of 1m+ … basically, I agree with you, **Meat**.

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**Author:** ![SentientMeat](https://avatars.discourse-cdn.com/v4/letter/s/43a26b/32.png) [@SentientMeat](https://boards.straightdope.com/u/SentientMeat)\
**Post date:** [August 20, 2009, 2:18pm UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/53 "2009-08-20T14:18:03Z")

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> [@billfish](#):
>
> I brought it up because I’ve never seen that data mentioned here. Is it because they have figured it doesnt really work? Is it because it hasnt been warming for long enough or warm enough for it to show in that data yet? Or is it because you don’t like the fact that it isnt actually showing a warming? Again, I have no idea either way.

Ah, apologies **billfish** , I assumed this was just another flyby from someone who deliberately wanted to draw attention away from overall global trends. Such data [does show an overall warming trend](http://www.arctic.noaa.gov/essay_romanovsky.html), but local data is susceptible to local changes - I gave **Chief Pedant** an example of how this might happen in the UK - and 1999 shows a particularly steep temperature drop in Fairbanks in particular, and Northern Quebec can be seen to buck the trend in the table. (Of course, AGW skeptics are the _first_ to jump on local phenomena when they are used to demonstrate global trends!) There are various ways of calculating global average temperature, but a new record shouldn’t be too controversial however it’s calculated.

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**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\
**Post date:** [August 20, 2009, 3:28pm UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/54 "2009-08-20T15:28:28Z")

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> [@Quartz](#):
>
> Why don’t you check the graph? It’s measuring total solar radiance; I’m talking about sunspots.

[http://www.ngdc.noaa.gov/stp/SOLAR/SSN/ssn.html](http://www.ngdc.noaa.gov/stp/SOLAR/SSN/ssn.html)

After 1975 the sunspot cycle did go up and down 3 times, it is getting close to the low cycle again. The sun’s radiance was one of the main reasons for the changes before AGW not the sunspots. Your idea has very little support now.

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**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\
**Post date:** [August 20, 2009, 4:37pm UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/55 "2009-08-20T16:37:41Z")

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> [@GIGObuster](#):
>
> [http://www.ngdc.noaa.gov/stp/SOLAR/SSN/ssn.html](http://www.ngdc.noaa.gov/stp/SOLAR/SSN/ssn.html)
> 
> After 1975 the sunspot cycle did go up and down 3 times, it is getting close to the low cycle again. The sun’s radiance was one of the main reasons for the changes before AGW not the sunspots. Your idea has very little support now.

Please stop going on about solar radiance - it’s got little to do with the theory I’m saying can be falsified. And please don’t try to bait me by saying it’s my idea. It isn’t: all I’m saying is that it can be falsified.

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**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\
**Post date:** [August 20, 2009, 8:59pm UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/56 "2009-08-20T20:59:44Z")

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> [@Quartz](#):
>
> Please stop going on about solar radiance - it’s got little to do with the theory I’m saying can be falsified. And please don’t try to bait me by saying it’s my idea. It isn’t: all I’m saying is that it can be falsified.

😕

The latest graph I posted does not deal with solar radiance, the sun spots virtually do not influence the current global temperature readings.

Do I have to suppose now that you are ignoring cites on purpose?

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**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\
**Post date:** [August 20, 2009, 10:00pm UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/57 "2009-08-20T22:00:06Z")

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> [@GIGObuster](#):
>
> 😕
> 
> The latest graph I posted does not deal with solar radiance,

That would be why you explicitly mentioned it in your text, then, wouldn’t it?

Sorry, but I’m leaving this.

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**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\
**Post date:** [August 20, 2009, 10:04pm UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/58 "2009-08-20T22:04:28Z")

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> [@SentientMeat](#):
>
> Ah, apologies **billfish** , I assumed this was just another flyby from someone who deliberately wanted to draw attention away from overall global trends.

No problem. Sometimes you forget who you are swinging at and why 🙂

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**Author:** ![intention](https://avatars.discourse-cdn.com/v4/letter/i/e95f7d/32.png) [@intention](https://boards.straightdope.com/u/intention)\
**Post date:** [August 20, 2009, 10:08pm UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/59 "2009-08-20T22:08:44Z")

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> [@SentientMeat](#):
>
> **intention** , thanks for dropping by. Your guesses for A) and B), however vague, would be most welcome. …

**SentientMeat** , thanks for the interesting questions. For reference, those were:

> [@](#):
>
> A) The shape of the CO2 concentration graph. Do you think it will level out? If so, at what level? (For info, the level stayed roughly constant at 280 ppmv for millennia before the Industrial Revolution)

Over what time period? Without that the question is not too meaningful.

Setting that aside, what seems to be generally forgotten is that the decay from the added CO2 in the air is exponential. In other words, if we were able to magically freeze the level of added CO2 to the current level (we currently add about 7 gigatonnes of C to the atmosphere annually), the atmospheric level would not continue to rise indefinitely. As more is added, more is sequestered annually, and at some point they become equal. At that point, airborne CO2 levels out. At some future date, that’s likely to happen … but when?

The problem is not predicting what the atmospheric CO2 level will be (although questions remain about the e-folding time, which affect the answer. See [Jacobson](http://www.stanford.edu/group/efmh/fossil/ClimRespUpdJGR%201.pdf) for a discussion of some of the issues.) CO2 levels can be calculated with reasonable accuracy if we know what the emissions will be. The problem is predicting emissions, and I know of no way to do that.

My own guess is that well before the end of the century a new source of power (algae derived biofuels? fusion? artificial photosynthesis?) will become widespread, and as a result the use of fossil fuels will decline. How much? Dunno. This is why the IPCC uses “scenarios”. These are projections that say “if emissions change by this much, airborne CO2 will change by that much”. They know that your question A) is not answerable in general, only for an assumed level of emissions.

> [@](#):
>
> B) The consequences of the level you guessed for A). For example, if we burned literally all the carbon stores we have access to, the level would rise above 800 ppmv = three times the historical average. Does anyone think that such a level would have no significant consequences?

There’s an error in this question, which is the idea that if we burn all of the carbon stores the CO2 would “rise above 800 ppmv”. Without specifying the time frame, that statement is incorrect. For example, if we maintain emissions at the current levels we’d eventually burn all the carbon stores … but the level would never come close to 800 ppmv.

My guess of the consequences, regardless of the level of probable change, is that they will be minimal. My own work suggests strongly that the earth has an equilibrium temperature that is set by the physics of wind, waves, and water. For those interested, my hypothesis is posted up at [Watts Up With That](http://wattsupwiththat.com/2009/06/14/the-thermostat-hypothesis/). I don’t want to hijack this thread, so please post any comments about the hypothesis at WUWT.

So my answers are A) haven’t a clue, and B) not much.

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<div class="post-metadata">

**Author:** ![GIGObuster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gigobuster/32/421_2.png) [@GIGObuster](https://boards.straightdope.com/u/GIGObuster)\
**Post date:** [August 20, 2009, 11:19pm UTC](https://boards.straightdope.com/t/the-co2-concentration-graph-guesses-solicited-for-its-future-shape-and-consequences/506391/60 "2009-08-20T23:19:58Z")

</div>

> [@Quartz](#):
>
> That would be why you explicitly mentioned it in your text, then, wouldn’t it?
> 
> Sorry, but I’m leaving this.

:rolleyes:

“After 1975 the sunspot cycle did go up and down 3 times, it is getting close to the low cycle again”

Yes, I did mention it, just remarking on the later does not negate that I did mention the former, but it is clear that you are ignoring the sunspot data.

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