Global warming: blast from the past

It’s the summer of  ’53. Elvis makes his first recording, Watson and Crick publish the structure of DNA … and Time magazine and Popular Mechanics report the very latest research findings:  it turns out that man-made carbon dioxide emissions are causing the Earth to heat up.

Gilbert N. Plass, 1920 – 2004	(AIP)

When did global warming get noticed by the mainstream press? It was earlier that you might think. In 1953 Time magazine and Popular Mechanics were running articles on the work of Gilbert Plass.

Physicist Gilbert N. Plass had just carried out some calculations on the atmospheric warming effect of carbon dioxide. He certainly wasn’t the first person to make such calculations, but he was the first to make use of computers to perform the calculations in much greater detail. He drew attention to the point that man-made CO₂ emissions would have a significant warming effect on the Earth’s temperature. Popular Mechanics reported the results under the headline “Growing Blanket of Carbon Dioxide Raises Earth’s Temperature”. In a way, Plass’ work marks the crossover into the modern era of climate research.

Tyndall, Arrhenius and Callendar

First, a quick detour into history. What was the state of play when Plass started his work?

John Tyndall.	Vanity Fair, April 6, 1872

Fourier (in 1824) and Pouillet (in 1838) were among the first to realise that the Earth’s atmosphere obstructs the passage of infrared radiation while being transparent to visible light from the Sun. From this, they concluded that one might expect the atmosphere to have a warming effect on the Earth.

These early ideas were put on a solid experimental footing by John Tyndall ^[1] in 1861. He measured the infrared absorption of various gases using a spectrophotometer, and found that certain trace gases in the Earth’s atmosphere, such as water vapour and carbon dioxide, were responsible for most of the infrared absorption. That is, these trace gases were responsible for most of the warming effect. It turned out that the most abundant atmospheric gases, N₂ and O₂, absorb very little radiation at infrared wavelengths.

The first detailed numerical calculations of the heating effect of CO₂ on the Earth’s atmosphere were performed by Svante Arrhenius ^[2], and published in 1896. He didn’t have the benefits of modern computer technology, and performed the entire calculation by hand:

I should certainly not have undertaken these tedious calculations if an extraordinary interest had not been connected with them.

S. Arrhenius ^[2]

The calculation took him several years; his wife left him halfway through it.

Prof. Svante Arrhenius

He calculated that temperature varies logarithmically with CO₂ concentration over the range he studied, and that a doubling of CO₂ concentration would result in a temperature increase of 5°C–6°C. He had very incomplete spectroscopic data to work with, but this very early result is within a factor of two of the modern value of a 3° C temperature rise per doubling of atmospheric CO₂ concentration ^[3].

An interesting next step was taken by Callendar in a 1938 paper ^[4]. Callendar had collated historical temperature data, and along with these he had brought together data on atmospheric CO₂ concentrations and fossil fuel use. He found a rising CO₂ concentration in his CO₂ data, and calculated that this could explain the rising temperature he had found in the weather record. Some of his data were weak, and his findings weren’t conclusive, but they served to draw attention to the question of man-made carbon dioxide emissions and rising temperatures.

Plass’ Work

This is where Plass came in.

Plass’ work took advantage of two new scientific advances. First, the infrared spectrum of the CO₂ molecule had been well characterised by now, so detailed and precise spectral data could be incorporated into his calculations. Second, computers with the power needed to perform such detailed calculations had also become available. These new computers allowed a very detailed wavelength-by-wavelength calculation of infrared transmission through the atmosphere to be carried out. Plass performed these computations wavelength-by-wavelength and altitude-by-altitude up through the atmosphere. He published the work in a 1956 paper ^[5]. The paper concluded that:

The latest calculations of the influence of CO₂ on the infrared flux show that if the CO₂ concentration in the atmosphere doubles the average temperature rises 3.6° C and if it falls to half of its present value the average temperature falls 3.8° C.

G.N. Plass, 1956 ^[5]

His result is very similar to the present day estimate of 3° C per doubling of CO₂ concentration ^[3], but the agreement isn’t as close as it appears, because Plass’ calculation didn’t take account of the follow-on effects of clouds and changes in water vapour concentration.

Plass also noted that man-made CO₂ emissions were the dominant effect altering the present-day atmospheric CO₂ concentration:

d.  Influence of man’s activities on climate

At the present time the burning of fossil fuels is adding more than 6×10⁹ tons per year of CO₂ to the atmosphere. Other activities of man such as the clearance of forests and the drainage and cultivation of land add additional amounts of CO₂ to the atmosphere each year. The total amount added each year from these sources is several orders of magnitude larger than any factor that contributes to the CO₂ balance from the inorganic world at the present time. Therefore this additional factor has greatly disturbed the CO₂ balance. [...] If no other factors change, man’s activities are increasing the average temperature by 1.1° C per century.

G.N. Plass, 1956 ^[5]

For further discussion of Plass’ paper, see J.R. Fleming’s commentary ^[6].

The Press Coverage

Plass’ work was a notable scientific advance, but one more thing stands out about it.

Plass’ work didn’t stay confined to the scientific journals. It also received significant coverage in the popular press. That media attention was some of the earliest press coverage of global warming. Popular science magazines and leading news magazines picked up on it. Time Magazine ^[7] carried the story in 1953, as did Popular Mechanics ^[8]. Plass himself wrote a lengthy article about his work in a 1959 issue of Scientific American ^[9].

Time Magazine

This is what Time magazine ^[7] had to say in May 1953:

Invisible Blanket
In the hungry fires of industry, modern man burns nearly 2 billion tons of coal and oil each year. Along with the smoke and soot of commerce, his furnaces belch some 6 billion tons of unseen carbon dioxide into the already tainted air. By conservative estimate, the earth’s atmosphere, in the next 127 years, will contain 50% more CO₂.

This spreading envelope of gas around the earth, says Johns Hopkins Physicist Gilbert N. Plass, serves as a great greenhouse. Transparent to the radiant heat from the sun, it blocks the longer wave lengths of heat that bounce back from the earth. At its present rate of increase, says Plass, the CO₂ in the atmosphere will raise the earth’s average temperature 1.5° Fahrenheit every 100 years.

As the blanket of CO₂ gets thicker, it also prevents the tops of clouds from losing heat as rapidly as before. The smaller temperature difference between cloud base and top cuts down the air currents which must circulate through the cloud before rain or snow can form. Lowered rainfall will make a drier climate. Less cloud cover will be formed, more sunlight will reach the earth, and the average temperature will rise still higher.

After thousands of years, says Professor Plass, plants and the slow-moving seas will absorb most of the excess CO₂. But for centuries to come, if man’s industrial growth continues, the earth’s climate will continue to grow warmer.

Time Magazine, May 25, 1953 ^[7]

Plass underestimated the rate at which man-made carbon dioxide emissions would grow, so he expected only a 1.5° F temperature rise per century, but other than that, it’s a remarkably accurate first-order estimate of the effect of carbon dioxide on the transmission of infrared radiation through the atmosphere.

Popular Mechanics

Popular Mechanics magazine ^[8] followed up with a brief article in its August 1953 edition:

Scanned image from Modernmechanix.com

Growing Blanket of Carbon Dioxide Raises Earth’s Temperature
Earth’s ground temperature is rising 1½ degrees a century as a result of carbon dioxide discharged from the burning of about 2,000,000,000 tons of coal and oil yearly. According to Dr. Gilbert N. Plass of the Johns Hopkins University, this discharge augments a blanket of gas around the world which is raising the temperature in the same manner glass heats a greenhouse. By 2080, he predicts the air’s carbon-dioxide content will double, resulting in an average temperature rise of at least four percent. If most of man’s industrial growth were over a period of several thousand years, instead of being crowded within the last century, oceans would have absorbed most of the excess carbon dioxide. But because of the slow circulation of the seas, they have had little effect in reducing the amount of the gas as man’s smoke-making abilities have multiplied over the past hundred years.

Popular Mechanics, August 1953 ^[8]

Scientific American

Gilbert Plass himself wrote an article summarising his work for Scientific American ^[9] magazine. It was published in the July 1959 edition:

Carbon Dioxide and Climate
A current theory postulates that carbon dioxide regulates the temperature of the earth. This raises an interesting question: How do Man’s activities influence the climate of the future?
[...]
The carbon dioxide and other gases in the atmosphere are virtually transparent to the visible radiation that delivers the sun’s energy to the earth. But the earth in turn reradiates much of the energy in the invisible infrared region of the spectrum. This radiation is most intense at wavelengths very close to the principal absorption band (13 to 17 microns) of the carbon dioxide spectrum. When the carbon dioxide concentration is sufficiently high, even its weaker absorption bands become effective, and a greater amount of infrared radiation is absorbed. Because the carbon dioxide blanket prevents its escape into space, the trapped radiation warms up the atmosphere.
[...]
We shall be able to test the carbon dioxide theory against other theories of climatic change quite conclusively during the next half-century. Since we now can measure the sun’s energy output independent of the distorting influence of the atmosphere, we shall see whether the earth’s temperature trend correlates with measured fluctuations in solar radiation. [...] But if carbon dioxide is the most important factor, long-term temperature records will rise continuously as long as man consumes the earth’s reserves of fossil fuels.

Gilbert N. Plass,
Scientific American, July 1959 ^[9]

Scanned image from Scientific American, July 1959

More Information

The history of global warming is covered in detail in several online resources and books. Spencer Weart has written a short history of the subject, “The Discovery of Global Warming” ^[10], and several websites provide a detailed historical background:

• Climate Change and Anthropogenic Greenhouse Warming:  A Selection of Key Articles, 1824–1995, with Interpretive Essays, J.R. Fleming, NSDL Classic Articles in Context, Issue 1, April 2008 ^[11]
• The Discovery of Global Warming, Spencer Weart, June 2009 ^[12].
  Spencer Weart’s website supplementing his book.
• The Carbon Dioxide Greenhouse Effect, Spencer Weart, September 2008 ^[13].
  A timeline of the history of research into the greenhouse effect.

The Appendix on page 2 of this post links to two of the key early papers, by Arrhenius and Callender, as well as to Plass’ main scientific paper on his work.

Page 2 →

References

1. On the Absorption and Radiation of Heat by Gases and Vapours, and on the Physical Connexion of Radiation, Absorption, and Conduction, J. Tyndall, Phil. Mag. ser. 4, 22, 169–194 & 273–285, 1861
2. On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground, S. Arrhenius, London Edinburgh Dublin Philos. Mag. J. Sci. 41, 237–276, 1896  (WebCite cache)
3. IPCC, 2007: Climate Change 2007: Synthesis Report, Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Core Writing Team, R.K. Pachauri and A. Reisinger (eds.) IPCC, Geneva, Switzerland, 2008  (Section 2.3, page 38)  (WebCite cache)
4. The Artificial Production of Carbon Dioxide and Its Influence on Temperature, G.S. Callendar, Quart. J. Roy. Meteor. Soc. 64, 223–240, 1938  (WebCite cache)
5. The Carbon Dioxide Theory of Climatic Change, G.N. Plass, Tellus 8, 140–154, 1956  (WebCite cache)
6. Essay about “The Carbon Dioxide Theory of Climatic Change”, J.R. Fleming, Classic Articles in Context, National Science Digital Library, 2008
7. Invisible Blanket, Time Magazine, May 25, 1953
8. Growing Blanket of Carbon Dioxide Raises Earth’s Temperature, Popular Mechanics, p.119, August 1953 (reposted in Modernmechanix.com, March 21, 2006)
9. Carbon Dioxide and Climate, Gilbert N. Plass, Scientific American, July 1959(reposted online December 4, 2008)  (scanned image of article)
10. The Discovery of Global Warming, Spencer R. Weart, Harvard University Press, October 31, 2008  (paperback)
11. Climate Change and Anthropogenic Greenhouse Warming:  A Selection of Key Articles, 1824–1995, with Interpretive Essays, J.R. Fleming, NSDL Classic Articles in Context, Issue 1, April 2008
12. The Discovery of Global Warming, Spencer Weart, September 2008
13. The Carbon Dioxide Greenhouse Effect, Spencer Weart, The Discovery of Global Warming, June 2009

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