Guest Post by Willis Eschenbach
I greatly enjoy reading old science. Back fifty years or more ago, they actually did real science, not the “my model says it must be true” kind of thing that we are treated to today. In that regard, I’ve been fortunate to stumble on one of the earliest papers on the greenhouse effect, “The Artificial Production of Carbon Dioxide and its Influence on Temperature” by G. S. Callendar. There were a lot of curious and interesting things in the paper, which I’d heard of but never read, and which I’ll touch on in no particular order.
I was greatly encouraged by the description of Callendar in the header of the paper, where he is listed as the “Steam technologist to the British Electrical and Allied Industries Research Association”. I liked the guy already, he is a hands-on man, someone who describes himself as a “technologist”, and working in industry. What’s not to like? Plus, he wrote the article by himself, no team of 24 “co-authors”.
One of the first things I noticed was that although I’ve at times complained of the long lag time between submission to a journal and eventual publication, this one says:
Manuscript received May 19, 1937-read February 16, 1938
Eight months before it was “read”, and the paper was eventually published in April of 1938.
Moving on, here is his abstract, or “Summary” as it was called in that time and place:
By fuel combustion man has added about 150,000 million tons of carbon dioxide to the air during the past half century. The author estimates from the best available data that approximately three quarters of this has remained in the atmosphere.
The radiation absorption coefficients of carbon dioxide and water vapour are used to show the effect of carbon dioxide on sky radiation. From this the increase in mean temperature, due to the artificial production of carbon dioxide, is estimated to be at the rate of 0.005°C per year at the present time.
The temperature observations at 200 meteorological stations are used to show that world temperatures have actually increased at an average rate of 0.005°C. per year during the past half century.
Being a numbers man, this interested me because as early as 1938 he’d estimated the total emissions, estimated the airborne fraction, and calculated the global temperature. So of course I had to go check it out, to see how his estimates compare to modern estimates.
The CDIAC has the carbon emissions data. The “past half century” from 1937 would have been 1887 to 1937. The CDIAC data puts the emissions during that time at 38,201 million tonnes of carbon. To convert to tonnes of carbon dioxide, we need to add the weight of the oxygen. The atomic weight of carbon is 12, and the atomic weight of oxygen is 16. The atomic weight of CO2 is 12 + 2 * 16 = 44. So we need to multiply 38,201 million tonnes of carbon times 44/12, which gives us 140,000 million tonnes of CO2, compared to Callendar’s estimate of 150,000 million tonnes … not bad, not bad at all.
As to the “best available data” estimate of the airborne fraction, Callendar says:
I have examined 21 very accurate set of observations (Brown and Escombe, 1905), taken about the year 1900, on the amount of carbon dioxide in the free air, in relation to the weather maps of the period. From them I concluded that the amount of carbon dioxide in the free air of the North Atlantic region, at the beginning of this century, was 2.74 ± 0.05 parts in 10,000 by volume of dry air.
This translates to 274 ppmv in the year 1900. I note that this is significantly less than the value given by the ice core data, which is about 295 ppmv.
The “pre-industrial” value in 1750 is usually set at 274 ppmv. This difference raises lots of interesting questions I won’t go into here. Unfortunately, although the Brown and Escombe 1905 paper is online here, it makes no mention of the “21 very accurate sets of observations”. I wish I had the data, particularly since his error estimate is ±5 ppmv.
I did like his method, though, which appears to consist of looking at the observations and the weather maps at the time of the observations. This would allow him to infer the source of the air being sampled at a given time, and to choose samples from say off of the ocean rather than from the town. Clever. From this he calculates a 6% increase in CO2 by 1937. Curiously, he had no actual figures for the CO2 in 1937, he estimated it. What do the modern ice core records say the increase in CO2 was from 1900 to 1937?
He then goes on to say:
Since calculating the figures in Table I, I have seen a report of a great number of observations on atmospheric CO2 , taken recently in the eastern U.S.A. The mean of 1,156 “free air” readings taken in the years 1930 to 1936 was 3.10 parts in 10,000 by volume. For the measurements at Kew in 1898 to 1901 the mean of 92 free air values was 2.92, including a number of rather high values effected by local combustion, etc.; and assuming that a similar proportion of the American readings are affected in the same way, the difference is equal to an increase of 6 per cent.
What truly impressed me, though, was the final sentence of that paragraph, which reads:
Such close agreement with the calculated increase is, of course, partly accidental.
Gotta love a scientist as honest as that.
From there he goes into a fascinating discussion of the physics of the absorption of upwelling longwave radiation, and the characteristics of downwelling longwave radiation. This is followed by another most interesting description of how he has estimated the temperature changes since 1900. Not having HadCRUT or Berkeley Earth or GISSTEMP datasets, of course, he had to go out, find the station data, and analyze it.
Surprisingly, he goes on to discuss the “urban heat island” (UHI) effect, saying:
It is well known that temperatures, especially the night minimum, are a little higher near the centre of a large town than they are in the surrounding country districts; if, therefore, a large number of buildings have accumulated in the vicinity of a station during the period under consideration, the departures at that station would be influenced thereby and a rising trend would be expected.
Clearly a man ahead of his time.
How well did he do? Here’s the comparison of his results with those of the Berkeley Earth Surface Temperature dataset.
Comparison, global temperature anomaly estimates of Callendar (1938) and Berkeley Earth Surface Temperature (2014)
Now, I gotta give Callendar full marks for that one. Despite the difference in the linear trends, which may be due to his reducing the trend to adjust for the UHI effect, his results correlate very well (0.84) with the modern estimate.
Then, another surprise. He talks about how the climate system is not static, but instead it responds to changing temperature, saying (emphasis mine):
On the earth the supply of water vapour is unlimited over the greater part of the surface, and the actual mean temperature results from a balance reached between the solar “constant” and the properties of water and air. Thus a change of water vapour, sky radiation and temperature is corrected by a change of cloudiness and atmospheric circulation, the former increasing the reflection loss and thus reducing the effective sun heat.
This is the earliest of the very few examples I’ve found of people expounding the concept that the temperature of the planet is self-correcting, that is to say that the Earth has inherent temperature-regulating mechanisms, and that it naturally balances at a certain temperature, and it corrects itself when it departs from that balance. As I have spent some years investigating, measuring, and writing about just exactly how that system works in practice, I tip my hat to him. In fact, I’m in the middle of writing yet another post about the clouds and the temperature interact to establish that balance.
From there, he segues into a speculation on whether changes in carbon dioxide levels could have caused the ice ages. He states that he doubts CO2 could have done it, saying:
I find it almost impossible to account for movements of the gas of the required order because of the almost inexhaustible supply from the oceans, when its pressure in the air becomes low enough to give a fall of 5 to 8°C in mean temperatures.
Now, here’s the beauty part. I’m so indoctrinated by decades of being inundated with alarmism that I fully expected Callendar to conclude by warning of the dangers of rising CO2, impending Thermageddon, plagues, famines, rains of frogs, and the like. But to my great surprise and pleasure, here’s what he actually wrote:
In conclusion it may be said that the combustion of fossil fuel, whether it be peat from the surface or oil from 10,000 feet below, is likely to prove beneficial to mankind in several ways, besides the provision of heat and power. For instance the above mentioned small increases of mean temperature would be important at the northern margin of cultivation, and the growth of favourably situated plants is directly proportional to the carbon dioxide pressure (Brown and Escombe, 1905): In any case the return of the deadly glaciers should be delayed indefinitely.
You can’t say fairer than that.
My best to all,
PS—A final thought. I was most impressed by a practice which I don’t see in the modern scientific journals. The journal invited comments and questions on the paper from no less than six other people knowledgeable in the field. Then the journal published their comments and questions along with Callendar’s answers to them, not three issues down the line, but at the bottom of Callendar’s study itself.
When I saw that, I had to laugh. Why? Because it’s identical to the format of a blog post. Someone puts up a head post, you read it, and at the bottom of the head post you read other people asking questions and raising issues, and the author of the head post responding to them right there.
How fascinating. The journals have abandoned that format of publishing the article along with the questions and responses at the same time … and instead, it’s become the format of the web.
DATA: Callendar’s paper, THE ARTIFICIAL PRODUCTION OF CARBON DIOXIDE AND ITS INFLUENCE ON TEMPERATURE, is here. When I said above that I “stumbled across” the paper, to be clear I came across it doing what I do from time to time. I go to the AGWObserver and do a search for the words “FULL TEXT”. His content changes, he’s always adding new stuff, and best of all, he tags everything that’s not paywalled. As a working man with no university library to call on, that’s invaluable to me … or if not invaluable, at least valued at the usual price of $39.50 per paper, which adds up very fast. So I was cruising along at the Observer looking at “FULL TEXT” items when I came to Callendar … my great fortune.
AS ALWAYS: If you disagree with someone, please QUOTE THE EXACT WORDS YOU DISAGREE WITH. It’s the easiest and most accurate way for us all to be clear about exactly what you are objecting to. I can defend my words. I cannot defend your paraphrase of my words. If you disagree, I implore you, QUOTE.