The political target of limiting the effect of Man-made global warming to only +2⁰C can never be attained.
Guest essay by Ed Hoskins
According to well understood physical parameters, the effectiveness of CO2 as a greenhouse gas diminishes logarithmically with increasing concentration and from the current level of ~390 ppmv, (parts per million by volume). Accordingly only ~5% of the effectiveness of CO2 as a greenhouse gas remains beyond the current level.
This inconvenient fact is well understood in the climate science community. It can be accurately modeled using the Modtran program maintained and supported at the University of Chicago.
The logarithmic diminution of the effect of CO2 is probably the reason why there was no runaway greenhouse warming from CO2 in earlier eons when CO2 levels were known to be at levels of several thousands ppmv.
Remarkably, IPCC Published reports , (TAR3), do actually acknowledge that the effective temperature increase caused by growing concentrations of CO2 in the atmosphere radically diminishes with increasing concentrations. This information is in their report. It is well disguised for any lay reader, (Chapter 6. Radiative Forcing of Climate Change: section 6.3.4 Total Well-Mixed Greenhouse Gas Forcing Estimate).
The diminishing percentage effectiveness of CO2 as a greenhouse gas as acknowledged by the IPCC and its concomitant diminishing temperature effect are as follows:
increment cumulative
0-100 ppmv: according to David Archibald / Modtran data ~2.22°C ~2.22°C
100-200 ppmv: plants die below this level of CO2 +~0.29°C ~2.51°C
200-300 ppmv: noted as the preindustrial CO2 level +~0.14°C ~2.65°C
300-400 ppmv: current level IPCC attributes all as Man-made +~0.06°C ~2.71°C
400-600 ppmv: business as usual till 2100 +~0.08°C ~2.79°C
600-1000 ppmv: improving levels for plant growth +~0.06°C ~2.90°C
Accounting for the diminution effect the actual temperature reductions achievable, the calculated achievable values are in the range of few hundredths to a few thousandths of a degree Centigrade. As the margin of error for temperature measurements is about 1.0°C, these miniscule levels the temperature effects for all the efforts of those nations attempting to control their CO2 emissions, (only about 12% of world CO2 emissions), are marginal, immeasurable and thus irrelevant.
These minute temperature changes have to be seen in the context of normal daily temperature variations at any a single location of 10⁰C to 20⁰C. It can be as much as 40⁰C to 50⁰C over the course of a whole year.
Although the IPCC tacitly acknowledges that this crucial diminution effect with increasing concentrations effect exists, it certainly does not go out of its way to emphasise it. Like the Medieval Warm Period, that they attempted to eliminate with the Hockey Stick graph in 2001, the panel knows that wide public knowledge of the diminution effect with increasing CO2 concentration would be utterly detrimental to their primary message.
“Man-made CO2 emissions are the cause of climate change”.
The IPCC certainly does not explain these devastating consequences for the CAGW theory in their Summary for Policy Makers. This is because the IPCC is an essentially political organisation, that is solely tasked with the promotion and presentation of Man-made Climate Change from CO2 emissions, as an accepted and non-contentious fact for world’s politicians.
Thus the IPCC is entirely misleading in its central claim for Policy Makers, as they say:
“Warming of the climate system is unequivocal. Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.”
Any unquestioning, policy making reader is lead to assume that all increasing CO2 concentrations are progressively more harmful because of their escalating Greenhouse impact. But the opposite is so.
From the present concentration of atmospheric CO2 at approaching 400 ppmv, only ~5% of the effectiveness of CO2 as a Greenhouse Gas remains.
This can only give rise to a maximum of a further of ~+0.21°C. Thereafter beyond 1000+ ppmv the effect of increasing levels of CO2 can only ever be absolutely minimal even if CO2 concentrations were to increase indefinitely.
It is for this irrefutable physical fact that the widely held alarmist policy ambition
“to constrain Man-made temperature increase to only +2.0 °C”
could in fact never be reached, however much more Man-made CO2 was emitted.
It is impossible to ever reach the much vaunted policy upper limit of +2.0 °C that has been promoted by politicians as a target upper limit of temperature effect caused by man-made CO2 emissions.
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Has anyone ever managed to get an alarmist to accept this? I’ve never seen it on the blogs I visit. Too much of An Inconvenient Truth, I suspect.
So it all hinges on guesses about feedbacks. No wonder R Lindzen focusses so much attention on getting empirical data on that detail.
It would be greatly appreciated if somebody could provide me with a layman’s way of explaining this to people. Even when I tell people the logarithmic path CO2 returns from additional
Your conclusion of we can’t get 2 deg C warming rests on your “5%” more statement. What exactly do you mean here? 5% of what? Unless you think climate sensitivity to CO2 is zero, there will be a contraption of CO3 that will yield a 2 C rise in temps as there is no upper bound to the sensitivity equation. As you said, it is logarithmic so the concentration may be high but it should be a finite & definable number.
Screwed up above. My apologies
It would be greatly appreciated if somebody could provide me with a layman’s way of explaining this to people. Even when I tell people the logarithmic path CO2 follows is not in dispute, just the shape of the curve, they don’t get it. Dr. Ball once explained it as painting a window black. Each coat is going to have less and less of an effect. But that doesn’t provide a good parallel explanation as to why. If anybody could help me out, it would be greatly appreciated.
Thanks in advance
Mike H … the 10th blanket doesn’t keep you a whole lot warmer than the first 9
MODTRAN calculates that 50% of the warming effect of current (almost 400 ppm) CO2 levels would be accomplished by just 20 ppm CO2 (for a tropical atmosphere w/ constant relative humidity):
http://www.burtonsys.com/climate/MODTRAN_etc.html
The NCAR radiation code says that 40 ppm CO2 would be needed to get 50% of the current CO2-caused warming, rather than 20 ppm, but, either way, the lesson is clear: we’re well past the point of diminishing returns w/r/t the warming effect of CO2.
The alarmist projections of wild increases in temperature are based on assumptions of dramatic amplifications of the warming effect through positive feedbacks. But for the tropical atmosphere MODTRAN calculates only +65% amplification from water vapor, and that’s really an upper-bound, because it doesn’t taking into account various negative feedbacks, such as water-cycle (evaporative) cooling.
Guest essay by Ed Hoskins
According to well understood physical parameters, the effectiveness of CO2 as a greenhouse gas diminishes logarithmically with increasing concentration and from the current level of ~390 ppmv, (parts per million by volume). Accordingly only ~5% of the effectiveness of CO2 as a greenhouse gas remains beyond the current level.
But at higher concentrations it will transition to a square root dependence which will give a higher sensitivity.
Isn’t this is EXACTLY the type of message that the 50:1 video needs to get across – i.e. the IPCC’s own ACCEPTED science says that warming will slow and take many years to reach the acclaimed doom and gloom ‘critical’ levels (if at all!)…….the trouble is that for a video presentation it needs to be made short and snappy for lay folk to grasp quickly……
Mike H part two:
Me too.
But I guess that a simple explanation would be one inconvenient truth too many for many “climate scientists”.
Kev-in-UK:
Got it in one.
Phil
Have you got a graphic of some kind that demonstrates your point? It is difficult to visualise your comment especially as you provide mo actual figures or links. Thanks
Tonyb
This is one of the reasons warmists bang on about ocean ‘acidification’. They know mother nature won’t play ball with warming so they need something else to scare the children with.
The sentence in chapter 2 AR4
“Note that for CO2, RF [radiative forcing] increases logarithmically with mixing ratio”
is so very well hidden. You would never know it was there if you didn’t read it.
Is Ed Hoskins going to tell us how the magic numbers were calculated?
” Thereafter beyond 1000+ ppmv the effect of increasing levels of CO2 can only ever be absolutely minimal even if CO2 concentrations were to increase indefinitely.”
One can add CO2 to the point where lead will melt on the surface of Venus. Just keep adding CO2 until you get to 92 bar of pressure at the earth’s surface. Then you have essentially recreated the Venusian atmosphere, and the surface temps would rise to 872 °F. Not sure why you think this statement is true.
“Accordingly only ~5% of the effectiveness of CO2 as a greenhouse gas remains beyond the current level.”
False. If CO2 concentrations were to increase indefinitely we could get to a situation where 90% of the atmosphere (which is now ten times more dense) then on up to Venus style atmosphere. This would entail a much larger than 5% increase in temperature. Isn’t 872 °F more than 5% greater than say 90-100 °F even when I convert to Kelvin. Let’s see 305 K vs 739 K. Yep that’s a >100% rise in K.
So please reword this information so that it is true if you mean something else. As written these are falsehoods. Adding CO2 would eventually effect atmospheric density. Are you talking about replacing part of the atmosphere with CO2 while maintaining the same atmospheric weight of 14lbs per square inch at sea level, so that the maximum would be 100% CO2 at one earth atmosphere of pressure sea level when finished? Obviously that cannot go on indefinately because you have to stop at 100%. So that must NOT be what you mean. So what do you mean?
The ‘alarmists’ pin their hopes on ‘positive feedbacks’, which, as an engineer who specialized in feedback systems prior to giving up Phd work as a lost cause, I find to be tenuous at best. If there were ‘positive feedbacks’ as the ‘alarmists’ believe the earth would have spiraled into a Venus like atmosphere hundreds of millions of years ago. The fact that it hasn’t if prima facia evidence that there are no large ‘positive feedback’; mechanisms at work in the earth-atmosphere system.
It makes even the non alarmist claims of climate sensitivity look ridiculous. http://wattsupwiththat.com/2012/08/13/best-volcanoes-and-climate-sensitivity/
There’s no concrete evidence that CO2 has any effect at all on global temperature … it could all be the soda bottle effect.
“recreated the Venusian atmosphere”
So how do you envisage the change in orbit?
This fact also explains why CO2 is so important in accelerating the warming at the end of an ice age, when atmospheric CO2 is very low.
Are there any other publications on this?
If this is true, then its implications are truly epic.
This annoys me:
“…According to well understood physical parameters, the effectiveness of CO2 as a greenhouse gas …..etc…”
The effectiveness of CO2 as a greenhouse gas is zero. The physical parameters are not well understood by the pseudoscientists pushing for global warming. There are two reasons for thinking that its effectiveness is zero. The first one is derived from the absence of any kind of warming for the last fifteen years. There is more carbon dioxide in the air now than ever before but it’s not doing its warming thing. Without warming, no greenhouse effect and no AGW is possible. Has that alleged warming ever existed? The answer is no. If you check the global temperature curve you will find that there has been no greenhouse warming for the last 100 years. The second reason is Ferenc Miskolczi. The correct way to determine the greenhouse effect is to account for the activity of all greenhouse gases present. In our case this means carbon dioxide and water vapor. Arrhenius did it only for carbon dioxide which leaves his theory incomplete. If you use both carbon dioxide and water vapor you find that an optimum window for absorption of infrared radiation exists that they jointly maintain. If you increase carbon dioxide and thereby increase IR absorption water vapor will diminish to restore the optimum absorption for the atmosphere as a whole. As a result, total absorption of IR by the atmosphere does not change when carbon dioxide is added, and this is what Miskolci observed in 2010. Such cooperation between the two greenhouse gases amounts to negative water vapor feedback, the exact opposite of what IPCC uses to get their very high warming predictions. Since greenhouse warming gets its energy from absorption of IR radiation and since total absorption no longer follows carbon dioxide concentration it follows that greenhouse warming is impossible. We see that of course today when the highest carbon dioxide ever has no warming effect.
A log graph of CO2 effect on temperature would be very appropriate for this article.
Mike H, here’s a stab at an explanation for laymen.
The misnamed “greenhouse” effect of greenhouse gasses like CO2 is based on the fact that they are not truly colorless. They have a “tint,” though we can’t see it, because it’s in a part of the light spectrum that our eyes don’t detect. GHGs are transparent in the visible part of the light spectrum, but they absorb (block) parts of the IR spectrum.
Adding such gasses to the atmosphere has a warming effect on the lower atmosphere, because the light arriving at the earth from the sun is much “bluer” (shorter average wavelength) than the light emitted from the earth. Because the earth is relatively cool, the light emitted from the earth is mostly IR. So anything in the atmosphere that blocks IR but is transparent to visible and UV will have a warming effect, because it lets in most of the arriving solar radiation (that warms the earth), but blocks a much larger percentage of the departing radiation (that cools the earth).
Even though CO2 levels are measured in parts-per-million, there’s nevertheless already so much CO2 in the atmosphere that it blocks nearly all of the IR that it can possibly block. So adding more CO2 doesn’t have much effect on temperature. For CO2’s main absorption bands, we’re way, way past the CO2 levels at which the IR is all absorbed. Only for very narrow ranges of wavelengths at the fringes of those absorption bands, where CO2 is a very weak absorber, can adding more CO2 appreciably increase the amount of IR blocked.
However, adding even a small amount of a different GHG (such as one of the CFCs or HCFCs) can have a much larger warming effect, by blocking a part of the IR spectrum for which the atmosphere would otherwise be transparent. That’s why you may read that CFCs like Freon-12 are thousands of times more potent as GHGs than CO2. It’s not that there’s anything fundamentally special about Freon-12, it’s just that there’s so few Freon-12 molecules in the atmosphere that some of their absorption bands aren’t already blocked.
Here’s an analogy. Consider moth-eaten blankets to be like GHGs, and different positions one the blankets correspond to different parts of the IR spectrum. The blankets have big holes in some places, but nice, dense wool fabric in others.
Different patterns of holes in the blankets are like different GHGs. They pass some parts of the IR spectrum, and block others. So “CO2” blankets have one pattern of holes, “CH4” blankets have a different pattern of holes, “CFC-12” blankets have yet another pattern of holes, etc.
Now, envision an obsessively compulsive neat-freak piling on moth-eaten blankets to try to keep warm in a chilly night. He exactly straightens and lines up each blanket on the bed.
If he piles on a dozen identical “CO2” blankets, with the holes all lining up exactly, he won’t be much warmer than if he had only one or two “CO2” blankets. But if he adds a “CH4” blanket, with many of its moth-holes in different places, then he’ll be a lot warmer, because some of the CO2 blanket’s holes will be blocked by the CH4 blanket, and vice-versa. And if he adds a “CFC-12” blanket, with some of its holes in different places than the holes in the CO2 and CH4 blankets, he’ll be warmer yet.
Right now, we’ve got about 10 or 20 CO2 blankets piled on. Adding another 5 or 10 or 20 CO2 blankets will keep us a tiny bit warmer at the frayed edges of the holes, but it won’t make near as much difference as adding some other kind of blanket.
Brian Macker;
False. If CO2 concentrations were to increase indefinitely we could get to a situation where 90% of the atmosphere (which is now ten times more dense) then on up to Venus style atmosphere.
>>>>>>>>>>>>>>>>>>>
Seriously? Since only 20% of the atmosphere is oxygen, how are you going to get CO2 over 20%? Or are you assuming some massive source of oxygen as yet unknown that will suddenly spring into existence in order to be converted to CO2? Or by “adding” CO2 do you mean brand new C and O that don’t exist anywhere at all coming into existence? By magic? Transported through a black hole maybe? Or big space ships that scoop it up from Venus and import it to Earth?
The rest of your comment is similarly irrelevant to any reasonable discussion of the science.
0-100 ppmv: according to David Archibald / Modtran data ~2.22°C ~2.22°C
Something wrong here: if you use Modtran for the first step, looking down from 70 km height, 1976 US standard atmosphere, no clouds or rain, the difference between 0-100 ppmv CO2 is near 7°C.
Modtran also says if you go from pre-industrial 280 ppmv to a double 560 ppmv, the temperature increase is ~0.9°C, which is quite different from the 0.14°C extra (from 300 to 600 ppmv) in your calculation. What is going wrong here?
Of course, that all is before any (positive or negative) feedbacks…