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.
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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.
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A quick google search reveals Stan Robertson the Architecture professor and graphics designer and Stan Robertson the Scots folk-singer. niether is likely to be this Stan Robertson. Can we have a thumb-nail bio?
“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.
I stopped reading right here. WTF?
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.
I still think we are looney if we think our measurement systems are accurate enough to track those tiny changes. For example, the net net overall average temperature change might only be 0.3 C or so. How do you measure that when 40 C swings are common annually, and in some cases, daily?
I’m sorry, but I just walked out of this ‘professors’ classroom muttering “another idiot”.
Soot melts the snow even when the temps are below freezing. Sun hits the soot, the soot retains the heat and the snow beneath it melts. It’s the soot, not the CO2 that we need to clean-up.
Plants need CO2 and we need plants.
This, of course, once again confirms the existence climate cycles – the great heresy of the Global Warming Cult.
The cult’s great ‘truth’ is positive feedbacks, despite the fact there is little or no evidence of them and none at all in the geological record.
Something interesting may be happening with global temperatures right now, as according to UAH, they are falling in an almost unprecedented fashion.
http://discover.itsc.uah.edu/amsutemps/
Ameliorate ozone problems? Now that could be a problem.
In the pre-AGW era thinking, it was believed the temperature history showed century scale movements much larger than we have experienced in the last ~ two centuries. It would be interesting to find out how that record and general agreement were discarded. My bet is that they were simply erased, a la hockey stick. But it would be worth documenting never the less.
I see that we are all doomed, according to the outgoing chief government scientific advisor, Sir John Beddington:
http://www.telegraph.co.uk/earth/environment/9951872/World-faces-decades-of-climate-chaos-outgoing-chief-scientific-adviser-warns.html
However all is not lost if his replacement Sir Mark Walport comes up with what he says:
“He is also a champion of open access to scientific research, the idea that the fruits of public or charity-funded research should be available to everyone, free of charge. He recently implemented a policy at the Wellcome Trust to penalise researchers who do not make their work available free of charge.”
Walport said he was “delighted and honoured” to have been appointed. “Science, engineering and technology have transformed the infrastructure of the modern world, and have a vital role to play at the heart of policy making,” he said.
“They are critical both to economic recovery and growth, and to addressing many of the greatest challenges of our time, such as environmental change and the ageing population. I look forward to working with colleagues both inside and outside government to ensure that the best possible advice can be provided from the most expert sources, based on the strongest evidence, to facilitate the wisest possible policy decisions.”
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.
Yes, natural phenomenon , balance of the warm and cold water flowing in an out of the Arctic Ocean, moving polar jet stream back and forth.
http://www.vukcevic.talktalk.net/NAP-SST.htm
Why would balance change ? Geology .
Geology? Sun, actually.
http://www.vukcevic.talktalk.net/SSN-NAP.htm
but nobody knows how and why, so CO2 as a handy scapegoat.
I’m still not alarmed.
Another point- that 390 watts is assuming that the earth acts as a blackbody. If it did, radiation out would quickly adjust to equal radiation absorbed- if that were the case, nighttime temperatures would quickly drop to the 2.7 K we get from “big bang” background radiation, and daytime temps would rise to 350 K, killing us all. If climate modelers knew anything, they would quickly throw in Newton’s law of cooling,
http://www.ugrad.math.ubc.ca/coursedoc/math100/notes/diffeqs/cool.html
and adjust the coefficient k to match current rates of cooling at night and warming during the day. Playing around with a simplified model, I discovered that starting with everything in balance, and a sine wave increase in temps during the day and decrease at night, then increasing the incoming radiation by a set amount- you gradually get a new balance of course- under the new balance, nighttime temps increase more than daytime temps- it’s obvious this must be the case, else we’d reach that 2.7K ” big bang” nighttime temperature.
The planet in the past has experienced far more extreme temperature paradigms (both much warmer and much colder) over far, far, longer periods of time than we are witnessing today.
Also, the earth has experienced CO2 levels in the past far higher And far lower than we have today and NO ONE seems to know what caused that. (Did dinosaurs drive SUVs and heat their dens with power generated by coal fired plants?)
In each instance the planet did not burn up and turn into Venus, nor did it turn into a giant iceball.
And NO ONE can explain what caused these historical climatic periods, NO ONE knows what caused them to reverse course – as they ALL did .
So, pray tell, why is any HONEST person concerned in the slightest about today’s climate?
If science still has much to learn about the multitude of variables, and their interaction, that affect climate (as evidenced by their ignorance in explaining the historical climate) , how can they presume to predict the future climate?
After all, if you cannot explain the historical climate, one cannot honestly claim they have the knowledge to predict the future climate.
By the way, is not water vapor the MOST IMPORTANT greenhouse gas, given that it constitutes well over 90% of all the greenhouse gases?
A woderfully concise explanation, the thing about physics is that it has no political colour, it just is.
Although I understand you are talking hypothetically, about the maths, the phrase:
“Thus while CO2 concentration is increasing exponentially with time, the temperature only increases linearly.”
would be better written:
“Thus if CO2 concentration were to increase exponentially with time, the temperature would only increase linearly.”,
or better still, to match closer to the real world:
“Thus if CO2 concentration were to increase linearly with time, the temperature would only increase by the log of that increase.”,
It remains true to this day: there is no evidence that increasing the concentration of CO2 in the atmosphere, particularly in the presence of convection, increases the Earth’s surface temperature. I like the way the young Russian Physics PhD candidate put it to me on the plane to Penang. “There is no mechanism,” she said. The idea that added agents of cooling will throttle or restrict or trap or block outgoing radiation is akin to an intelligence test.
This morning on the BBC Today programme Sir John Beddington, who has just retired as the UK Government’s Chief Scientific Adviser, said that current climate reflected the global CO2 levels of 25 years ago and that today’s increased CO2 levels would be reflected in global temperatures 25 years from now.
This implies that global warming lags rising CO2 levels by 25 years. I do not remember seeing this before in any climate change models. Have I missed something or is this a new hypothesis that has been specifically designed to explain the apparent failure of global temperatures to increase over the last 14 to 16 years?
You take no account of the PROPORTION of atmospheric CO2 is down to us which is 3-4%, the rest is from natural producers from Volcanoes to insects through plants at night etc., etc., etc..
There are no peer reviewed papers proving CO2 drives climate/temperature but plenty concluding no connection between CO2 and temperature. None of the GHE theory predictions have been found or happened so your insistance that CO2 drives climate/temperature, though you claim small, is built on sandy wind blown ground. The constant proof of the connection between CO2 and climate from the alarmists are model outputs all of which rely of factoring in CO2 as the driver. This is NOT proof but a circular argument and fails.
We live on a dynamic planet with a chaotic climate system driven by insolation NOT some trace gas vital for life.
Er . . . “Thus while CO2 concentration is increasing exponentially with time, the temperature only increases linearly.” ?????
CO2 is NOT increasing exponentially with time. Starting out totally wrong.
And not only the issue comparing rates of warming in the modern record, the instances of COOLING in the presence of higher CO2 concentration for the modern and ancient record obliterates the alarmist position. The debate over the CO2 lag in the Vostok ice record always seems to focus on the periods of temperature rise, (with the alarmist guess saying that CO2 somehow ‘took over’ the forcing later..) – but never about the decline in temperature after CO2 had already risen.
If increased CO2 concentration actually provided any amount of forcing to ‘help’ temperature go up then, once that concentration was higher – why didn’t it seem to have any affect on preventing temperature from coming back down?
From a systems viewpoint, you could postulate the exact opposite that the ice record is showing us that increasing of CO2 dampens whatever was causing temperature to go up. In other words, CO2 is a lagging negative feedback and any delayed negative feedback is always going to produce an oscillation. Warming produces more CO2, the CO2 builds up to some level putting the brakes on temperature which then starts going down and CO2 lingers driving temperature even further down that whatever forced it up in the first place. Works for me…
I wonder where Bob Tisdale is to explain the two separate increases in temperature 1917 to1944 and 1976 to 2000.
I like the way the young Russian Physics PhD candidate put it to me on the plane to Penang. “There is no mechanism,” she said. The idea that added agents of cooling will throttle or restrict or trap or block outgoing radiation is akin to an intelligence test.
This is the point I have been making for several years. CO2, and all GHGs, also have a cooling effect on heat in the atmosphere. While they do warm the surface slightly they also cool the atmosphere. These two complimentary effects balance out which is exactly what we’ve seen over a billion years of history.
Solomon Green says: March 25, 2013 at 5:44 am
I heard the same and thought another one crying the sky is falling, not now, but soon. Sheesh.
I am also not happy with Stan Robertson’s story. Could we please have an explanation in simple first year physics on the ‘forcing’ of CO2 compared with the performance of H2O.
This essay treats the global temperature as a function of radiative physics and – as far as I can tell – does a decent job of looking at the basic mechanism of the radiative energy balance, but this is not what drives global atmospheric temperatures and therefore I am not sure that this is the right premise on which to refute the IPCC claims.
Most of our near-earth atmosphere (where the measurements used to estimate the “global temperature” are made) has an energy balance dominated by evaporation and precipitation since the majority of the earth’s surface is covered either permanently or intermittently by water. I am not even sure the radiative physics equations can be applied above the surface layer either because of the impact of cloud formation on energy transfers as well as vertical air movements.
It is quite clear that the observed warming cannot – in any way – be considered to be unusual in the past 60 years, and thus cannot be ’caused’ by anthropogenic increases in atmospheric CO2. However, I don’t think we can use these radiative physics equations to refute the IPCC claims. To be honest, if it were that easy, I suspect we wouldn’t have had to go on for so long with this disaster of a theory!
Thanks for the essay, Stan, the numbers are really useful and i will keep them for future reference but I am sad to say that I doubt it will sway too many people.
grumpyoldmanuk says:
March 25, 2013 at 4:44 am
“A quick google search reveals Stan Robertson the Architecture professor and graphics designer and Stan Robertson the Scots folk-singer. […]”
========================================================
Could be either. It doesn’t take a rocket scientist to see that CO2 doesn’t have what it takes to drive climate; that the assumed positive feedbacks used in the models were an incorrect assumption; that catastrophic anthropogenic CO2-based global warming isn’t happening.
Heck! I’m still waiting for Greenland to warm up past the good ol’ days of the Vikings so I can perhaps do a little homesteading over there. Greenland is almost there, but it’s still a little colder than Greenland’s farming heyday back when.
I’m thinking a Scots folk-singer might be a little overqualified to pick apart CAGW, but I have to agree with you here. A short bio tacked on the end, as in most other guest posts, is always nice.
Best regards from a slightly-grumpy-from-shoveling-snow-at-5:00am H.R.
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.
All it needs to do? Do you think that the Earth is some sort of sentient being with intentions? What matters is what it actually does.
I can see lots of ways that the Earth could actually cool with increasing CO_2. I can imagine it remaining neutral. I can think up ways where it warms a little bit, or warms a lot. None of this ultimately matters — what matters is what it does, and once we understand it, why. At the moment we do not understand it — we understand pieces of it. The “changes in horizontal and vertical heat distribution” you so glibly refer to is one of the bases of the GHE — it is computable (subject to some assumptions, but they are assumptions like “assuming that the laws of quantum physics are valid”, and “assuming that the atmosphere doesn’t nonlinearly react to the change”). It is the all things being equal baseline assumption that small changes in CO_2 concentration don’t cause the entire system to suddenly reconfigure and that radiation physics per se holds.
Of course, even here there are assumptions that are not written down. The most important ones (as the article notes) are feedback with water vapor (nothing else really matters as far as feedback is concerned, as even if there is methane feedback, it breaks down quickly to CO_2 in the upper atmosphere and is biologically broken down to CO_2 in the ocean too fast to be a player itself), modulation due to OTHER atmospheric components, e.g. soot, dust, aerosols (many of which are net cooling), and although the article does NOT discuss it in any detail, modulation of albedo both from ice/snow and from clouds tops. There are also slower acting players in the game whose quantitative effects we cannot even guess at — orbital modulation, oceanic turnover, the effects of phase changes in the major global atmospheric oscillations.
Could these all combine to produce net cooling on top of weak CO_2 driven warming? Sure. Could they all combine to produce net warming on top of weak CO_2 driven warming? Absolutely. Could these all combine to produce net warming or net cooling on top of no change in CO_2? Obviously (glancing at the presumed global thermal record and pretending that the error bars are small enough that it has some reasonable probability of being valid) it has, repeatedly, in the past produced net warming and net cooling both on top of no significant change in CO_2 levels.
And ultimately, if you read past the beginning, this is all the article talks about. One could summarize the article as:
“Natural variability in the twentieth century produced a warming rate in the first half that almost precisely matched the warming rate in the second half, with a flat-to-cooling hiatus in between. In the first half of the century, CO_2 was completely irrelevant to the warming. In the second half, its direct warming effect was a larger but still very small fraction of the observed warming. In both cases, since we cannot actually compute the contribution of natural factors to the warming or explain the warming observed in the first half (or the cooling of the LIA, or the warming of the MWP, or the cooling before that, or the warming of the RWP, or the cooling from the mid-40’s through the mid-70’s in the twentieth century, or…) we cannot conclude that high-sensitivity CO_2 warming was responsible for the temperature rise in the second of the two rises in the twentieth century.”
At that, he pulled some of his punches. He did not point out, for example, that temperatures reached a 1950’s-like plateau as of the 1997-1998 super-ENSO event and have been more or less flat for some fifteen to sixteen years even as CO_2 levels have increased significantly. He didn’t point out that they were nearly flat — except for a few bobbles associated with e.g. Mount Pinatubo — for the decade preceding that, and that far from smoothly increasing in consonance with CO_2 concentrations, the apparent explanation is that the ENSO event is responsible for more or less 100% of the observed warming from this era in a punctuated equilibrium model.
In the end his conclusion is identical to yours — that CO_2 increases are not a good explanation for the observed temperature rise — so far. Of course this year temperatures could spike up 0.3 C and resume a “torrid” pace, or they could continue their doldrums, or they could even drop. A sudden rise would constitute evidence supporting the CAGW point of view. A sudden drop would constitute negative evidence. Continuing flat temperatures constitute weak negative evidence (accumulating to eventually become strong evidence).
So if we’re going to anthropomorphize the Earth and imagine that it is going to do what it “needs” to do according to your belief system (or theirs!), let’s all agree to try to let the Earth speak for itself instead of claiming to speak for it. Science works better that way.
rgb
StephenP says:
March 25, 2013 at 5:13 am
‘However all is not lost if his replacement Sir Mark Walport comes up with what he says:
“He is also a champion of open access to scientific research, the idea that the fruits of public or charity-funded research should be available to everyone, free of charge. He recently implemented a policy at the Wellcome Trust to penalise researchers who do not make their work available free of charge.” ‘
————————————————————-
I shouldn’t get too excited about Walport if I were you. He is a convinced warmist.
‘Sir Mark Walport, Director of the Wellcome Trust, responded to the series, saying: “Al Gore described climate change as ‘An Inconvenient Truth’, but the findings of this study offer a very convenient truth. Reducing greenhouse gas emissions is not only essential to help tackle climate change, it is also an important way to improve public health.
“We urge world leaders, when they meet in Copenhagen next month, to take account of the health impacts of different mitigation strategies, and to work towards a solution that improves both the health of our planet and its people.” ‘
http://www.wellcome.ac.uk/News/2009/News/WTX057672.htm
and (the source of the above link):
‘This is also the man who, in July 2011 was adding to his voice to the complaints that the BBC was giving “too much weight to fringe views on issues such as climate change”.
So, as we shiver through the unseasonable weather, hardly daring to venture out into the biting easterly wind, these fools prattle and prance with the quasi-religious mantras.
You will get nothing sensible from Walport. He is pure establishment. But then that is the joy of being a warmist – you can keep repeating the same old, same old, never having to admit you are wrong. And the idiots in government will always give you a nice cushy job.’
http://www.eureferendum.com/blogview.aspx?blogno=83748