The Single Most Important Point

Given all the activity of late challenging various aspects of the IPCC’s work, I wanted to remind folks of probably the most important assumption in the IPCC (and related climate models) that seldom makes the media.

Greenhouse gas theory alone does not give us a catastrophe.  By the IPCC numbers, originally I think from Michael Mann in 1998, greenhouse warming from CO2 should be about 1.2C per doubling of CO2 concentrations.  But the IPCC gets a MUCH higher final number than this.  The reason is positive feedback.  This is a second theory, that the Earth’s temperature system is dominated by very strong net positive feedback effects.  Even if greenhouse gas theory is “settled,” it does not get us a catastrophe.  The catastrophe comes from the positive feedback theory, and this is most definitely not settled.

I usually put it this way to laymen:  Imagine the Earth’s climate is a car.  Greenhouse gas theory says CO2 will only give the car a nudge.  In most cases, this nudge will only move the car a little bit, because a lot of forces work to resist the nudge.  Climate theory, however, assumes that the car is actually perched precariously at the very top of a steep hill, such that a small nudge will actually start the car rolling downhill until in crashes.  This theory that the Earth is perched precariously on the top of the hill is positive feedback theory, and is far from settled.  In fact, a reasonable person can immediately challenge it by asking the sensible question  — “well, how has the climate managed to avoid a nudge (and resulting crash)  for hundreds of millions of years?”

I got to thinking about all this because I saw a chart of mine in Nicola Scafetta’s SPPI report on climate change, where he uses this chart:

I am happy he chose this chart, because it is one of my favorites.   It shows that most of the forecast warming from major alarmist models comes from the positive feedback theory, and not from greenhouse gas theory.  Let me explain how it is built.

The blue line at the bottom is based on an equation right out of the Third IPCC Report (the Fourth Report seems to assume it is still valid but does not include it anywhere I can find).  The equation seems to be from Mann 1998, and is for the warming effect from CO2 without feedbacks.   The equation is:

∆T = F(C2) – F(C1)
Where F(C) = Ln(1+1.2c+0.005c^2+0.0000014c^3)

So the blue line is just this equation where C1=385ppm and C2 is the concentration on the X axis.

The other lines don’t exist in the IPCC reports that I can find, though they should**.  What I did was to take various endpoint forecasts in the IPCC and from other sources and simply scale the blue line up, which implicitly assumes feedback acts uniformly across the range of concentrations.   So, for example, a forecast after feedback of 4.8C of warming around 800ppm was assumed to scale the blue no feedback line up by a uniform factor of 4.8/1.2 = 4x.  For those who know the feedback formula, we can back into the implied feedback fraction (again not to be found anywhere in the IPCC report) which would be  4=1/(1-f)  so f=75%, which is a quite high factor.

** This seems like a totally logical way to show the warming effect from CO2, but the IPCC always insists on showing just warming over time.  But this confuses the issue because it is also dependent on expected CO2 emissions forecasts.  I know there are issues of time delays, but I think a steady-state version of this chart would be helpful.

  • hunter

    “Climate theory, however, assumes that the car is actually perched precariously at the very top of a steep hill, such that a small nudge will actually start the car rolling downhill until in crashes”

    That is so wrong in so many ways it’s just pathetic. Seriously, where do you get these ideas from? Nothing that remotely resembles them can be found in any climate physics textbook or paper.

    And how embarrassingly ignorant you are, to think that Mann 1998 was where CO2 sensitivity equations came from. You can trace that back to Arrhenius 1896, in fact.

  • – hunter

    You clearly are one of those people who can’t follow a chain of logic. This post wasn’t about “CO2 sensitivity equations” – it was about feedback theory. And the CO2 sensitivity he did mention is well documented and accepted by both sides of the debate. So stop letting your emotion drive your logic, and know the facts before you spew out garbage.

  • j ferguson

    Another car/feedback analogy might be with steering. The caster or toe-in on the front wheels of a car cause the car to prefer to go straight (more-or-less). If the direction of the car deviates from straight ahead, the front wheel caster geometry tends to “correct” by steering car back to straight.

    This would be crystal clear should you ever drive a car where the caster has been removed. I did. It was a Sprite and it was a bear to keep in the lane. i had to drive it every inch of the trip.

    This business with the “tipping point” only makes sense if we can assume that humans are causing a combination of conditions in the environment that has never happened before and which will trigger a heretofore unprecedented positive feedback to this “unprecedented” combination.

    And also there will be no simultaneous “tipping point” provocation of an unprecedented negative feedback.

    a lot of assumptions.

  • hunter (the realone)

    AGW true beleivers suffer from an inability, as we see, to think things through.
    Strong positive feedbacks are what AGW depends on.
    If there are no strong feedbacks, then we are not at risk for a climate crisis.
    And then the AGW community demands are simply more demands, not imperatives that must be followed.

  • Charles Higely

    The IPCC’s 1.2 deg C warming from doubling of CO2 is itself not settled at all. It was 0.10 deg C before they started altering numbers.

    If you go back and check their “science” you will see that they altered one of the thermodynamic constants upward by 12-fold. What was a 0.1 Deg rise with doubling became 1.2 deg C rise. Then they cobble onto this the positive feedback fantasy.

    At the time they did this, they lauded the constancy of this particular constant over time at the same time that they were changing it. It’s a sleight of hand trick, pretending that the new value had been there all of the time. Liars.

  • Charles Higely

    A good look at the work of Miskolczi and Zagoni puts CO2 in better perspective. Basically Miskolczi has looked at the thermodynamics of water vapor and CO2 and found that they interact such that, as CO2 rises, absolute humidity decreases, creating a relatively constant heat-trapping effect, if not a decreased effect with an increasing proportion of CO2.

    Essentially, CO2 is irrelevant to climate. Too much CO2 could even cool it, due to increased proportions of CO2 which is less effective than water vapor as a heat-trapping gas.

    Dr. Zagoni beautifully sums it up all up:

    “Since the Earth’s atmosphere is not lacking in greenhouse gases [water vapor], if the system could have increased its surface temperature it would have done so long before our emissions. It need not have waited for us to add CO2: another greenhouse gas, H2O, was already to hand in practically unlimited reservoirs in the oceans.”

    “Earth type planetary atmospheres, having partial cloud cover and sufficient reservoir of water; maintain an energetically uniquely determined, constant, maximized greenhouse effect that cannot be increased further by emissions. The greenhouse temperature must fluctuate around this theoretical equilibrium constant; [change] is possible only if the incoming available energy changes.”

    Good Summary:

    Formal Presentation by Zagoni: Ferenc Miskolczi’s Saturated Greenhouse Effect Theory.

    Add to this the fact that warmists like to talk about the theoretical effect of doubling the CO2 as if it is a possibility.

    CO2 partitions between water and air at 50 to 1. Thus, to double atmospheric CO2, we would have to emit 50 times as much as the oceans soak it up. That’s a lot of CO2!

    In fact, there is not enough available carbon to accomplish this feat. If we worked at it, we might be able to add 20%. That means a warming (at 0.10 deg with doubling) of 0.02 deg C or 0.24 deg C with the IPCC’s inflated values (1.2 deg with doubling).

    Feedbacks are cute, but why pretend that the CO2 idea is alive at all? Dress it up all you want, the corpse is dead!

  • McHarris

    Copenhagen might be over, but they are not sitting quietly licking their wounds.

    The discussion paper, published — but not distributed — on Dec. 14, 2009, assumes that the goal of the green economic transformation is the same as that of the ill-fated Copenhagen conference: a 50 percent reduction in global carbon dioxide emissions by 2050. That, the paper says, will require a staggering $45 trillion dollar to accomplish — much of it in transfers from rich nations to poorer ones.

  • hunter

    “If you go back and check their “science” you will see that they altered one of the thermodynamic constants upward by 12-fold. What was a 0.1 Deg rise with doubling became 1.2 deg C rise. Then they cobble onto this the positive feedback fantasy.”

    Not a bad Monckton parody. The problem you have is that he’s pretty much too ridiculous to parody. To make it more believable you could at least invent a name for the “thermodynamic constant”.

  • Hunter, funny that nobody ever refers to Arrhenius’ 1906 correction, perhaps because it was in german?

  • BenAW

    “And how embarrassingly ignorant you are, to think that Mann 1998 was where CO2 sensitivity equations came from. You can trace that back to Arrhenius 1896, in fact.”
    Assuming you are referring to this publication:
    Svante Arrhenius, 1896, On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground, The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science
    you may want to check this one:
    Svante Arrhenius 1906, Die vermutliche Ursache der Klimaschwankungen, Meddelanden från K. Vetenskapsakademiens Nobelinstitut, Vol 1 No 2

    Appears the original sensitivity calculations in the first publication were for WATERVAPOR, not CO2.
    Perhaps reconsider terms like “embarrassingly ignorant” next time you make this kind of claims as fact.

  • Roger Taguchi

    Interesting comments on a valuable website! Re: The Single Most Important Point: yes, the ASSUMED positive feedback effect is DOUBLE the effect of CO2 alone, giving rise to a predicted warming 3 times that due to CO2 alone. I have shown that when a real-world 0.7 degree temperature increase from 1850 (or 1750) to now is used to check the prediction of increasing CO2 from 300 ppm to 400 ppm, the net feedback is essentially zero. Obviously, assuming even a linear effect, one-third of a 3 degree increase on doubling CO2 from 300 ppm to 600 ppm should give a 1 degree rise; because of saturation effects (diminishing returns), the rise of temperature should be LESS THAN LINEAR, so that the rise in temperature should be MORE THAN 1 degree (e.g. 1.4 degrees) on increasing CO2 from 300 ppm to 400 ppm. This is way too high when compared with the historic data (0.8 degrees being the reasonable maximum, which is why this figure is used by the warmists). Therefore the ASSUMPTION of positive feedback is way too high (when various corrections are made to the argument, the net feedback is close to zero). I can send a WordPerfect document (version X3) or a pdf file of my manuscript on request to my home email address of