CO2 did not drive the rapid warming of the 20th century.
Story submitted by Stan Robertson
The difference between a good idea and a bad idea is often a quantitative matter. For example, many people would think it a good idea to replace internal combustion engines with electric motors. But if the intent is to reduce the burning of fossil fuels then switching to electric motors would not help unless the electricity was generated without burning fossil fuels. Some people think that it has been a good idea to use corn to produce ethanol for a fuel, however, I am not one of them because the energy return on investment is either negative, or minuscule at best. From the standpoint of greenhouse gas emissions, it is a horrendous loser. It may be a biofuel and cleaner burning, might help ameliorate ozone problems and etc, but considering that nearly a gallon of oil is consumed in addition to the gallon of ethanol produced and burned, it is a quantitative loser. (Not that I care at all about the CO2.)
One of the ideas that seems to be widely believed is that human produced greenhouse gases, chiefly CO2, has dominated the warming of the earth in the last century. It is a simple quantitative matter to show that this is completely false.
According to the calculations of the UN IPCC, a doubling of the atmospheric concentration of CO2 (with an accompanying rise of other greenhouse gases) would reduce the outgoing infrared radiation from the earth by a net 2.7 watt/m^2 at the top of the atmosphere. This is known as the “climate forcing” that will occur along with a doubling of the CO2. This is a relatively straightforward, but messy calculation. I have repeated the IPCC calculation for CO2 and obtained a larger number, but after including the IPCC adjustments for other greenhouse gases and the effects of sulfate aerosols accompanying coal burning, we agree. It is important to note that the surface temperature increase that will accompany the CO2 is proportional to the logarithm of the CO2 concentration. Thus while CO2 concentration is increasing exponentially with time, the temperature only increases linearly.
In order to maintain equilibrium with the incoming UV/VIS radiation received by the earth, the surface temperature would need to increase enough to allow it to radiate an additional 2.7 watt/m^2 at the top of the atmosphere after any CO2 doubling. At a nominal surface temperature of 15 C (288 K), the earth surface radiates about 390 watt/m^2 on average, but the radiation that exits the top of the atmosphere is only 240 watt/m^2. Thus the earth would need to produce an additional (390/240)x2.7 watt/m^2 = 4.4 watt/m^2 at the surface in order to offset the direct effect of doubling the atmospheric CO2. At 288 K, the earth radiates an additional 5.4 watt/m^2 per 1C of temperature rise. Thus the direct effect temperature increase of a CO2 doubling would be 4.4/5.4=0.8 C.
At the present 0.5% per year rate of increase of CO2 it will take about 140 years to double its concentration. But as we all know, a 0.8 C temperature increase in 140 years is not the result that the UN IPCC is alarmed about. The IPCC climate models include large positive feedback effects that raise their expected temperature increase into the range 2 – 4.5 C, with their most probable value at about 3 C.
There are four main arguments against this: (1) We have already had half of a 2.7 watt/m^2 climate forcing since pre-industrial times. That has been accompanied by only 0.8 C temperature increase. As shown below, there are reasons for believing this to be due primarily to natural causes. (2) There is no evidence that confirms the existence of any large feedback effects since the end of the last deglaciation. (3) The rate of temperature increase within the past century has been within the bounds of normal climate variability and (4) as shown below, the heating effect of CO2 has been quantitatively inadequate to explain the actual warming that has occurred in the last century.
There have been two periods of rapid warming that account for most of the warming that occurred in the last century, as shown below.
Let’s examine the first of these rapid warming periods first. By 1944, the atmospheric CO2 concentration had increased from the pre-industrial level of about 280 ppm up to 310 ppm. At that time the concentration was increasing at a rate that would require about 600 years to double. The fraction of a doubling climate forcing that would have occurred by 1944 would have been log(310/280)/log(2)=0.15 and this would have contributed at a rate of 0.15×2.7 watt/m^2 per 60 decades, or 0.0068 watt/m^2 per decade. It’s direct warming effect at the surface would thus be only (390/240)x(0.0068 watt/m^2 per decade)= 0.01 watt/m^2 per decade. This would have raised the temperature by (0.01 watt/m^2 per decade) /( 5.4 watt/m^2 /C) = 0.002 C per decade. This is such a pitifully small fraction of the 0.174 C per decade rate of heating that occurred 1917-1944 that it is pretty clear that CO2 had nothing to do with the warming of the first half of the last century. Even the IPCC climate modelers concede this point.
But there is still more to be learned from that period. Apparently some natural phenomenon allowed the earth to absorb energy at a significant rate and produce the temperature increase of the first half of the century. Let’s see how much that might have been. To begin, the earth would have had to take in enough heat to at least produce the additional surface radiation that would accompany a temperature rise of 0.174 C per decade 1917-1944. This would be (5.4 watt/m^2/C)x(0.174C/decade) = 0.94 watt/m^2 per decade. This is already 94X the CO2 heating rate.
But, in addition, as shown by both the ARGO buoy system and heat transfer calculations, at least 700 meters of upper ocean can respond to heating on a time scale of a decade. The additional amount of heat required to raise its temperature by 0.174 C per decade would be c*d*0.174C, where c= 4.3×106 joule/m^3/C is the heat capacity of sea water and d= 700 m, or 5.2×10^8 joule/m^2. Dividing by the number of seconds in 10 years, this would be an average of 1.7 watt/m^2 per decade. But since it would start at zero, it would have to end at 3.4 watt/m^2 per decade in order to attain this average. This should be added to the 0.94 watt/m^2 per decade surface radiation losses by the end of the warming period. So the total heating rate would have to ramp up by 4.3 watt/m^2 per decade to provide the warming that actually occurred in either of the rapid warming periods. This is 430 times the direct CO2 surface heating for 1917-1944.
Since essentially the same rate of temperature increase occurred 1976-2000, we can compare 4.3 watt/m^2 with the heating that might have been caused by CO2 in the last part of the last century. From 1944 to 2000, the CO2 concentration increased from 310 ppm to 370 ppm, with a doubling time of about 140 years. The corresponding climate forcing that would have caused, at the surface, would be (390/240)x(log(370/310)/log(2))x(2.7 watt/m^2)/14 decades = 0.08 watt/m^2 per decade.
Due to the higher rate of growth of CO2 concentration in the second half of the 20th century, this is 8X as large as the direct surface heating effect caused by CO2 in the first half. Nevertheless, it is still some 54 times smaller than the rate of heating that actually occurred.
These straightforward calculations make it painfully obvious that CO2 forcing is not what drove the two periods of rapid heating during the last century. Until there is some understanding of the natural causes of these rapid warming periods and their inclusion in the climate models, there is no reason to believe the models. This is simple first year physics.
===========================================================
Stan Robertson, Ph.D, P.E, retired in 2004 after teaching physics at Southwestern Oklahoma State University for 14 years. In addition to teaching at three other universities over the years, he has maintained a consulting engineering practice for 30 years.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Careful Mike M, You’re in danger of starting the next Global Cooling scare.
You’ve just generated the perfect mechanism to explain the sudden onset of the next glaciation. /Sarc
It depends on the angle of the sun relative to the sooty surface. At the poles the angle of the suns rays are very acute so although it would play a part in the melting it’s the long wave back radiation that does the persistent melting. Even on a cloudy day sooty snow will melt and patches of soot will drill their way down bellow the surface of the clean snow. Back radiation is a product of the atmosphere and so it is always directly overhead of the surface.
CO2 is NOT increasing exponentially with time. Starting out totally wrong.
Ah, so which is it? Is it a vast international conspiracy to fake the direct observational evidence of a roughly exponential increase, or is it that the instrumentation — all of it at multiple observatories — is faulty? Would you have any actual source of evidence supporting this statement (since there are multiple sources of evidence to the contrary)?
Sheesh. And people wonder why “warmists” make fun of “deniers”.
I’ve got a good idea. Let’s agree not to issue a blanket statement that some measured result is false on WUWT without at the same time presenting precisely the same evidence that would be required to publish a paper refuting it. I’m not talking about criticizing speculative, complex theories, I’m talking about direct measurements.
For example, a good (if too short) list of things that should be out of bounds without evidence include direct instrumental measurements such as:
a) Satellite measurements of temperature. Criticizing this is fine — if you have evidence sufficient to write a paper that could in principle convince e.g. Roy Spencer that UAH has an error. Otherwise, this is a nearly direct instrumental observation and while it is not beyond any doubt it is beyond any reasonable doubt unless and until a specific problem is discovered.
Things that do not count as specific problems include “but it isn’t returning the result that I want it to return”, by the way.
b) Atmospheric CO_2 concentration. Again, this is a direct instrumental observation (actually the average of a whole series of many direct instrumental observations from many observatories). You can argue about the published numbers, sure, or can claim that there is surplus CO_2 on the top of volcanic mountains in Hawaii, but in the end, you need to both experimentally confirm this on site and present alternative measurements that suggest that it is, in fact, introducing a systematic error. Which is a fine subject for a published, peer reviewed paper.
c) Top of the atmosphere or bottom of the atmosphere spectra. This is again right in there with satellite measurements of temperature. The instrumentation is relatively straightforward, and it returns the results it returns. You may not LIKE the results they return, but if you don’t like the raw measurements, the onus is on you to demonstrate a systematic problem with the instrumentation, which is (IMHO) very, very unlikely to happen. But if you do, many journals would be happy to publish it so that your assertions can be openly debated.
d) SLR. This actually goes for the “warmist” side much more than the skeptical side. I’m sick and tired of hearing assertions of multimeter SLR by thus and such a time given actual instrumental records stretching back 140 years with a total SLR over that entire interval of nine whole inches, with a current rate of roughly 3 whole millimeters a year (just over an inch a decade), and with similar rates clearly observable in the historical record in almost precise correspondence with the temperature records illustrated in the top article above.
Note well that I’m perfectly happy to see things like “ice melt rates” derived from complicated gravitational and surface measurements criticized, and in fact these “instrumental” results HAVE HAD recent papers published criticizing them the “right” way. Instrumentally derived results can indeed be faulty, but they aren’t faulty because somebody says so, they are judged faulty because further evidence is accumulated that more or less confirms an error in what was done before.
Or did you mean that the rate isn’t exactly exponential? Like this matters?
rgb
Today I woke up to the BBC saying: “climate sceptics do not think CO2 causes warming” (or similar words).
I know we don’t think that, and worse, I’ve told everyone in the BBC who I could think to tell from the Chairman to the legal department.
And now … what do I find when I turn to WUWT … a clear demonstration that sceptics support the science of CO2 warming. We just reject the non-science of Hansen, Mann and the BBC.
According to the chart, the two peaks are ~60 years apart. AMDO/PDO cycle comes to mind. I think what we have witnessed is the belated non-recognition of this cycle, first described in 1996, just a few short years after the celebrated discovery of AGW, placement of the UNFCCC, and it’s brainchild, the IPCC. The IPCC is famous, and in fact chartered, to paper-over anything which does not comply with AGW, such as the discovery of AMDO/PDO a few years after it was chartered.
As I read Stan’s contribution, which was well done in math, that 60 year cyclicity stood out like a sore thumb. Grudgingly, looking at the lack of heating over the past ~15 or more years, some cheerleaders have actually now conceded that AGW heating is being masked by a natural cooling trend which might continue for a decade or two before resuming AGW heating.
Which might be partially correct, assuming that the sun really does have a miniscule effect on gaia climate. But we really don’t know what role the sun plays in the AMDO/PDO cyclicity yet, do we? And if the sun has gone all quiet on us now, and predictions are that it will go even quieter, something which we noticed centuries ago matching up with the LIA, then what tipping point might yet be in our 21st century at a half-precession old interglacial happening at a 400kyr eccentricity minimum?
Well the last one (MIS-11) went long, running somewhere between 22-32kyrs. If CO2 was involved in that extension (a) there is not much evidence to support it in the paleo record, and (b) if it was then there had to have been some natural occurrence, we may not have been on-stage just yet. So, it could happen. But MIS-19, ~800kyrs ago, didn’t go long. That would make it a coin toss unless CO2 is the heathen devil gas it is made out to be.
Which is what makes this so fascinating. If you do not want to in any way impede mother nature’s side of the coin from landing up, instead of down, you will want to remove any chance of impeding the onset of the next ~90kyr long glacial. You will then set about removing said climate security blanket. Which, from a human speciation perspective, might not be such a bad idea. However, if you leave the so-called climate security blanket in place, even grow it, then you increase the chances of the AGW side of the coin landing up, reducing the opportunity for a return to glaciation and concomitantly for genus Homo speciation. Honestly, as I look around me these days, I am not at all sure that would actually be a good thing.
Decisions……..Decisions…………
What I find just as, if not more, interesting about the chart you used is the “pause” in warming between ~1944 -~1976.
Didn’t I read somewhere recently that a “standstill” of 30 years while CO2 emissions continue to rise invalidates the models?
Things that make you go Hmmmm…
What I find just as, if not more interesting in the chart of warming rates is the “pause” in warming from ~1944-~1976. Didn’t I read recently that a “standstill” of 30 years while CO2 emissions continue to rise invalidate the models?
Things that make you go Hmmmm…
Mike M says:March 25, 2013 at 6:10 am
Good point Mike. I have always had a problem with temperatures crashing at the highest levels of CO2 in the ice core proxies, and then pretending that CO2 is driving the temperature, doesn’t work for me.
I could see a scenerio where a little CO2 enhances temperature, but at some point replacing WV with CO2, the latter a less efficient GH gas, causes cooling.
Pedant note: Etc. means “and others”, so you’ve basically said “and and others”.
/pedant
Ed_B says:
March 25, 2013 at 4:46 am
“In order to maintain equilibrium with the incoming UV/VIS radiation received by the earth….
I stopped reading right here. WTF?….
>>>>>>>>>>>>>>>>>>>>>>>>>>>>
He is taking THEIR assumptions and calculations and showing that even using that as a starting point the Climate Models flunk first year physics because the leave out the elephant in the room, aka what are the natural causes of climate variability that effected the first half of the 20th century.
Reblogged this on Rashid's Blog.
For all those who are “reading so far” then stopping on principle because the essay includes IPCC-think phrases, perhaps you should read through and think what’s being said.
Certainly, as I read it, the author is NOT endorsing the IPCC model. In fact, he’s doing exactly the opposite and using its own premise to invalidate itself. And any model which invalidates itself can’t be correct except by chance.
Well said, JA (5:19 AM, 25 March 2013).
Add to that the probable 13% atmospheric concentration of CO2 during the Rodinian glacial episodes (three documented) and one should be left with more questions than answers.
And for those “faint sunners” who continue to point to the difference in solar output, remember that your hypothesis hinges on heat being “trapped” by CO2, not on the amount of radiation being emitted at the source and absorbed by the receiver.
Plus, when the sun was even fainter, in the Early Proterozoic, with similar carbon dioxide concentrations, the average global temperatures were more like what we are accustomed to, not super-cold, and not super-hot.
There is absolutely no correlation between atmospheric carbon dioxide concentrations and average global temperatures.
Period.
Mark H.
Stan Robertson: The only thing I ask: when you use one of my graphs, please provide a link to the source of the graph:
https://bobtisdale.wordpress.com/2011/12/12/part-2-do-observations-and-climate-models-confirm-or-contradict-the-hypothesis-of-anthropogenic-global-warming/
Regards
” considering that nearly a gallon of oil is consumed in addition to the gallon of ethanol produced and burned”
Let me guess – this is from the infamous Patzek, Pimental Berkley paper.
I stopped reading at that point. One of the reasons I consider WUWT credible is that the posts generally are considerate of the references and do not choose junk science to substantiate a non-credible argument.
I end my reading with the sentence above and conclude that this post is junk.
Ed_B said:
“After 5 years of reading here I guess I still don’t get it. All that I see is that the earth needs to change its vertical and horizontal heat distribution system a bit. That would mean a tiny bit wider belt of thunderhead clouds, with a slight increase in frequency, a slight increase in ocean surface heat towards the poles, with a tiny increase in temperature at the poles”
Agreed. Have been saying as much for years.
Does anyone else share my puzzlement about the way in which people write about the current, observed increase in CO2 concentration in the atmosphere. It seems to be mandatory to say “CO2 is increasing exponentially” with an implied “with time” – though this is seldom ever stated explicitly. In his third paragraph Stan Robertson states ” Thus while CO2 concentration is increasing exponentially with time, the temperature only increases linearly. ” . What always puzzles me is that if you actually plot CO2 concentration against Time it plots as a sloping monthly sawtooth – or possibly sinusoid – which has an almost exactly constant slope when measured over a number of years. At present it is increasing effectively linearly with time. In fact, if you explore Mauna Loa data using various regression models the underlying (annual) response is remarkably close to being an exact straight line. Higher order terms are virtually absent. Where, then, does the oft quoted “exponential” character of the atmospheric CO2 concentration arise?
Am I being particularly thick? My understanding of the meaning of “exponential” as a description of the behaviour of a curve is that it implies a continuously changing slope. If the exponential term is positive the slope increases continuously. One can of course also fit a regression model in which the underlying idea is that the measured quantity increases (or decreases) towards an asymptote at a rate that diminishes as the x variable increases, eventually approaching zero.
If CO2 is indeed increasing in concentration linearly with time then the underlying physics leads to the conclusion that the increase in temperature that this produces will tend towards an asymptote. This is what almost everyone seems to believe, and arguments abound about just how large or small the exponential constant is. It is usually expressed in the context of global climate as the increase in CO2 concentration that is required to produce a factor 2 increase in temperature rise.
The corollary is that if CO2 /is/ increasing exponentially the (short term) response of temperature increase should be linear.
]
Can someone please sort me out?
Robin
Anyone who accepts that the Earth emits real radiative energy at the black body flux which assumes a sink at absolute zero, is a lunatic. This makes all climate alchemists lunatics. They believe that they’re right because pyrgeometers measure temperature then convert it by the S-B equation to Power, also the potential flux to a sink at absolute zero. This is also lunacy but includes the meteorologists as well!
The real operational radiative emissivity is ~0.16 (63 W/m^2/396 W/m^2). This is easily predictable because the GHG thermal emission is black body, a simple quirk of physics, and annihilates the same emission bands from the surface.
There is no GHG forcing except for non self-absorbed trace gases and water vapour side bands. Much more IR goes to space via the Atmospheric Window.
The modellers exaggerate GHG absorption by a factor of 6.85 = 157.5 W/m^2/23 W/m^2. None of it is CO2 – three separate bits of physics. This is the cause of the imaginary warming and imaginary feedback.
Don’t believe me? Go and talk to any process engineer or professional physicist who has done a bit of experimental heat transfer measurement in industrial plants.
And I don’t see Ed_B’s comment as anthropomorphic as does rgbatduke.
All that happens is that the atmosphere obeys the Gas Laws as it must.
There’s a Stan Robertson who posts here
“The Definitive Global Climate Change (aka Global Warming) Thread — General Discussion and Questions”
http://www.peakprosperity.com/comment/149210
Seems to be the same guy
Pffffft…. the GHE hypothesis is hogwash anyway… all of this is moot.
rgbatduke says:
March 25, 2013 at 7:22 am
CO2 is NOT increasing exponentially with time. Starting out totally wrong.
Ah, so which is it? Is it a vast international conspiracy to fake the direct observational evidence of a roughly exponential increase, or is it that the instrumentation — all of it at multiple observatories — is faulty?
The amount of CO2 in the atmosphere has supposedly increased from 280 ppm around 1900 to 390 ppm now, about a century later. 390/280 = 1.393. If the rate of increase is exponential, the exponent is 0.00332. That’s a pretty small exponent, hardly distinguishable from linear over a small time frame like a century or two.
CO2 rising exponentially? It’s barely quadratic!
Exactly. All that fuss is based on 30-year long AMO positive phase. Exactly such one occurred in 1910-1945, when warming reached 0,7C. No model is able to simulate this, since models are not able to simulate natural variations like NAO, AMO or PDO cycles.
How does one arrive at the “relatively straightforward, but messy calculation” – doubling the CO2 will reduce the outgoing IR radiation at the TOA by a net 2.7 W/m2? Some spectroscopists seem to disagree, saying, based on actual measurements, that it is a far smaller figure. Does anyone have a link to a detailed explanation?