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.
reply to Mike H. @ur momisugly 1:16
Here are a couple of ideas. The molecules of the atmosphere interact with the energy (wavelengths). Look toward the sun and you see bright yellowish light. The nitrogen and oxygen (most of air) scatter the blue wave lengths and other “colors” pass to the surface. The sky appears blue away from the sun because there are sufficient molecules to do the scattering. Now climb a mountain. High up the atmosphere has fewer molecules – not enough to facilitate the scattering. Sunlight is more intense but the sky is less blue and tends toward black. Reverse your hike. Go down. The number of molecules doing their thing increases, and the sky gets blue again.
Now, another mental jump. Earth’s surfaces provide radiation (ir) that interacts with various molecules in the atmosphere, CO2 being one of them. At pressures found in the atmosphere there are a certain number of molecules. To get more there has to be a greater depth or a higher concentration (mole fraction) –see:
http://www.esrl.noaa.gov/gmd/ccgg/about/co2_measurements.html
The ir-interactive gases provide a mechanism for a result (slowing the loss; if that phrase will do) similar to the idea of getting a blue sky. As the molecules accumulate, after a certain effect has been achieved (sky is blue) (warmth is provided) there is nothing left to do (within the normal bounds of the system). Want a more blue sky – create more oxygen and nitrogen gas and pump it into the atmosphere. I don’t think so.
Lets try the idea of Dr. Ball again but with the monitor you use with your computer. Go to the kitchen and grab a long sheet of “wax paper” –
When held in front of the monitor you will be able to read the text. Still, the paper is absorbing some of the energy coming from your screen. True, this is not IR radiation but I think you could turn your oven on low, open the door and hang a weekend edition of a major newspaper in front of the source to get a closer approximation by feeling or measuring the ir. But keep going:
Now fold the paper in half and try again. Still readable.
Do again. Still visible but going . . .
Continue. Depending on the quality of your wax paper . . .
by 5 or six doublings you cannot see text.
A couple more doublings and the light is extinguished**. **See below
Add all the paper you want – most all that can happen, has happened. Likewise with CO2.
The CO2 being added to the atmosphere is helpful to plants.
Sleep well.
**key physics concepts include ‘optical depth’ and ‘extinction coefficient’ among others:
http://en.wikipedia.org/wiki/Optical_extinction#UV-Vis-IR_absorption
http://scienceworld.wolfram.com/physics/OpticalDepth.html
In any case, the energy still has to be removed from the system in some form and some manner. In some ways the so-called GHGs both slow and facilitate the removal.
Ferdinand Engelbeen
That is possible true but more than highly unlikely to actually happen anytime in the next few million years. In fact the point you are making is irrelevant to the discussion of the guest post.
Burning all the carbon is impossible, atmospheric O2 of 16% or more is required for combustion.
Where did this “+2.0 °C” come from?
@ur momisugly Kev in the UK — good for you to post at ALL with little kids to take care of.
And, all you wonderful scientists above may (likely do not) not need my feedback, but, for what it’s worth:
WAY TO GO, WUWT SCHOLARS!!! YOU ARE THE BEST.
I am SO THANKFUL you take the time to explain and to so conscientiously respond to one another (and to the confused from the Cult, too). YOU ARE SO COOL!!!
Heh, heh, sometimes, I’ll arrive at a thread only to find no one there but me. Silence. Before long, though, BOOM, BOOM, BOOM, BOOM, BOOM, BOOM, the sound of the feet of the Science Giants steadily heading this way. What a joy to listen to you all — BAM! BAM! BAM! — demolishing the speculation and conjecture of AGW, one by one. What a privilege to observe your reasoned, well-informed, discourse. We laypersons are SO BLESSED to be present at your discussions.
Thank you.
Here it is again in ‘proper’ format.
Mmmmm. Let me also speculate.
Rob JM, I believe your explanation is somewhat flawed. If 60 ppm absorbs 75% of the IR then doubling the CO2 to 120 ppm will reduce the 25% energy remaining by 75% not 50% resulting in the remaining energy being 25% of 25% or 6.25% making the total attenuation 93.75% rather than 87.5%. Continuing this process i believe your table should be:
30ppm = 50%
60ppm = 75%
120ppm = 93.75%
240ppm = 99.61%
480ppm = 99.998%
@berniel
The IPCC has accepted the logarithmic nature of CO2 infact it is explicit in their calculations
(http://www.ipcc.ch/publications_and_data/ar4/wg3/en/ch3s3-5-2.html#table-3-10)
2. The simple relationship Teq = T2xCO2 x ln([CO2]/280)/ln(2) is used (see Meehl et al. (2007), Section 10.7, and Table 10.8), with upper and lower values of T2xCO2 of 2 and 4.5°C.
The reason for the log divided by log calculation is the log for C02 effect is base 2 (Anthony actually left that out of the article)
Standard rules for log base conversion
Log(b,x) = log(c,x) / log(c,b)
b is the base you want to convert from.
c is the base you want to convert to.
So yes the IPCC and all climate scientists accept the logarithmic nature of CO2 effects the questions comes down to the forcing multiplier
Lots of very insightful information here. Even without the analogies the theory of CO2 GHG catastrophe is stripped bare. For me the lightbulb moment was Arno’s mention of what Miskolci observed in 2010 and the confirmation based on OBSERVATIONS as graphed here:
http://www.friendsofscience.org/assets/documents/FOS%20Essay/SH400vsCO2.jpg
Game over!
h/t friends of science
…and I might add this shone through despite the troll distractions and misdirections.
One more thought: Why would there be any great debate about the pause? Its pretty evident, surely?
@berniel
I forgot to say that the entire article is consistant with the lower bound value of the IPCC
1. IPCC (2007a) finds that the climate sensitivity is likely to be in the range 2°C –4.5°C, with a ‘best estimate’ of about 3°C, very unlikely to be less than 1.5°C and values substantially higher than 4.5°C ‘cannot be excluded’ (IPCC (2007a, SPM).
See the lower bound sensitivity they quote => very unlikely to be less than 1.5°C
The argument above is basically that the sensitivity is towards the lower bound and if you can establish the CO2 forcing sensitivity is low then what is written would also be accepted by the IPCC.
dcfl51 says:
May 8, 2013 at 3:02 pm
Miskolczi’s result shows that, as near as dammit, the fall in humidity matches the increase in CO2
==========
High school chemistry. Partial pressure of gasses. If you increase CO2 something else must decrease or the pressure must increase. So either there will be less water vapor or the pressure will increase. However, if the pressure increases it is harder to evaporate water, and there will be less water vapor in the atmosphere.
So, in all cases, adding CO2 reduces the water vapor in the atmosphere. Unfortunately climate scientist were so busy taking biology and arts classes, they missed the chem class on partial pressure.
daveburton says:
May 8, 2013 at 2:47 pm
“Negative feedback can reduce the magnitude of an effect, but never to zero.”
Strictly speaking, that is not true.
John Finn says:
May 8, 2013 at 3:40 pm
“The average height at which radiation is emitted to space, therefore, increases…which means that the surface and atmosphere will warm”
It means there is more surface area radiating to space. And, since that surface area increases while the surface area back-radiating to the planet at worst stays the same, but more likely decreases, that means heat gets eliminated more efficiently. Result: surface cools.
You can’t get warming by arguing that the outer radius of the effective radiating surface is increasing. We went through that on Willis Eschenbach’s “Steel Greenhouse” thread.
Here is a simple derivation of the formula which allows simple calculations (and provides for the logarithmic chart). There was a thread a few months ago where Jan Perlwitz from GISS was questioning this simple formula and I wasn’t checking my email enough to respond in time but here it is now.
Temp C Response = TempC/Forcing * Forcing
Either shown as (the IPCC shortcut method):
Temp C Response = 0.81C/W/m2 * 5.35*ln(CO2ppm/280ppm) ;
or alternatively, (Temps will increase by 3.0C per CO2 doubling, same math):
Temp C Response = 3/ln(2) * 5.35*ln(CO2ppm/280ppm)
Now: ln(X/Y) = ln(X) – ln(Y)
Temp C Response = 0.81*5.35*ln(CO2ppm) – 0.81*5.35*ln(280)
Temp C Response = 4.33 * ln(CO2ppm) – 24.4
Now we traditionally say the anomaly of temperature versus today was -0.4C when CO2 was 280 ppm (1760 or so); so,
Temp C Anomaly = 4.33 * ln (CO2 ppm) – 24.8C
Now you can put in any CO2 number you want into that formula and what will pop out is what the theory of global warming at 3.0C per doubling says the temperature anomaly will be.
It will look like this (note I threw in some historic temperatures which do not follow the trends at all anyway – something else is the driver):
http://s4.postimg.org/pi837i4b1/Logarithmic_Warming_3_C_per_doubling.png
In practise however, the IPCC has a lag of when temperatures catch up to the GHG doubling and the chart looks more like this on the IPCC AR5 trendline – Zoomed-in to see it a little better).
http://s23.postimg.org/uyfrmdsvf/Zoom_In_Log_Warming_IPCC_Trendline.png
Can someone tell me the atmospheric CO2 level at which the absorption of IR bands are completely saturated?
With and without an increase in water vapor.
Mike H.
“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”
Try the sponge analogy. You see CO2 and a Sponge both absorb something. CO2 absorbes energy … a sponge absorbes water. The problem arises when you only have so much water. … or in CO2’s case energy. SO … you have this drop of water … you take a little sponge, and it makes the sponge wet. The bigger the sponge the less wet it will become. Eventually you’ll reach a size sponge where the sponge seems to remain dry. Getting a bigger sponge is not going to make any difference … it’s still going to seem dry.
Likewise .. There is only so much incoming and outgoing energy. There comes a point where more an more CO2 doesn’t do anything, because you’ve already reached a level of CO2 that absorbes all of the radiation that is supplied.
Is this analogy correct … of course not .. .but you’re talking about lay people. They know about Sponges. 🙂
John Finn
“I think there might be a bit more to it than you suggest. As more CO2 accumulates it increases concentration in the higher, colder, drier regions of the atmosphere. The average height at which radiation is emitted to space, therefore, increases. Because more emission is taking place at colder altitudes the rate of IR emission falls (S-B Law). This creates an imbalance whereby:
Incoming Solar Energy is greater than Outgoing IR energy
which means that the surface and atmosphere will warm – and continue to warm until equilibrium (incoming=outgoing) is re-established.”
I have read this plausible snippet before.
Gas below the radiating average height will be increasing their output too. It is not immediately obvious that the average radiative height will increase.
I like to think of it as adding tiny fin extensions to my lawn mower, I would expect it to run cooler.
Cheers
My question is this:
If CO2 absorbs IR, why does the heated CO2 not expand? and rise? and transfer the heat to the
upper atmosphere?
The more heat the more convection. No?
I keep reading that GHGs trap heat.
Solids can trap heat; the glass roof of the greenhouse; the insulation in your wall; a blanket.
What am I overlooking?
If the Sun sets, even a little bit, CO2 means nothing.
I just don’t get the focus on what means nothing.
Then again, it is a living for so many who publish now days.
So,,,,, perhaps a song that applies to both trends?
Since water vapor and CO2 both trap heat at the same wavelength at what humidity level is water vapor effectively the only green house gas. My estimate would be 10-15 percent. Anyway if we burnt everything we could I doubt we could get over 1500ppm.
Think there is too much CO2 argue with a plant
Never argue with a fool they will lower you to there level and beat you with experience.
Brian Macker writes “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.”
No you haven’t “essentially recreated the Venusian atmosphere”. Venus has only trace amounts of water vapour in its atmosphere. If you were to hypothetically quickly add say 60-80 kms depth of what would become liquid CO2 under that pressure, then our ocean would still float on top of that to a depth of around 2-3kms and the oxygen/nitrogen atmosphere we have now would be atop that.
Why would you assume it wouldn’t stratify?
As no sunlight would reach the 60-80kms of liquid CO2 then there is no reason to expect it to warm the planet in anything like the way Venus is warmed.
All hypothetically of course.
Wikth respect to the warming effect of CO2: 2 billion years ago, the Earth’s atmosphere was about 20 percent CO2, iu.e., 500 times the present concentration, before this CO2 was converted to oxygen by blue-green algae phoitosynthesis (and some part of it also later into animal skeletons, e.g., in corals, as carbonates, and ultimately into carbonate rock). And since the atmosphere was significantly thicker then, with perhaps as much as a third of it blown off later by asteroid impacts, that the actual CO2 inventory before the blue-green algae kicked in was more like 750 times the amount today.
It would seem that far more than even Earth’s original CO2 inventory would have led to extreme warming, if large concentrations really did have a linear oir nearly linear incremental effect. But that didn’t happen because even 20 percent in the atmosphere wasn’t enough to prodfuce that effect.
Venus is a totally different case – not only nearer the Sun, but its atmosphere is so thick that ground-level pressure is close to 100 times that on Earth. The heating on Venus is likely less due to CO2, even as 95% percent of the atmosphere, than to the compression. It’s the same effect you have in the cylinders of a diesel engine – compressing the fuwl mixture heats it oi very high temperatures, sufficient for ignition.
ghl;
I like to think of it as adding tiny fin extensions to my lawn mower, I would expect it to run cooler.
>>>>>>>>>>>>>>>>>
Moving energy via conduction (fins on your lawn mower) is a different set of physics from moving energy via radiance.