The general warming of the climate that has occurred in the last 60 years has been variously explained. Among the explanations are fluctuations in the amount of energy received from the sun, changes in the amount of volcanic dust in the atmosphere and variations in the average elevation of the continents.
According to a theory which was held half a century ago, variations in the atmosphere’s carbon dioxide can account for climatic change. The theory was generally dismissed as inadequate. Dr. Gilbert Plass re-examines it in a paper which he publishes in the American Scientist and in which he summarizes conclusions that he reached after a study made with the support of the Office of Naval Research. To him the carbon dioxide theory stands up, though it may take another century of observation and measurement of temperature to confirm it….
…. The atmosphere acts like the glass of a greenhouse. Solar radiation passes through to the earth readily enough, but the heat radiated by the earth is at least partly held back. That is why the earth’s surface is relatively warm. Carbon dioxide, water vapor and ozone all check radiation of heat.
Of the three gases that check radiation, carbon dioxide is especially important even though the atmosphere contains only 0.03 percent of it by volume. As the amount of carbon dioxide increases, the earth’s heat is more effectively trapped, so that the temperature rises.
... According to Dr. Plass, the latest calculations indicate that if the carbon dioxide content of the earth were doubled the surface temperature would rise 3.6° C and that if the amount were reduced by half the surface temperature would fall 3.8° C...
...Despite nature’s way of maintaining the balance of gases the amount of carbon dioxide in the atmosphere is being artificially increased as we burn coal, oil and wood for industrial purposes. This was first pointed out by Dr. G. S. Callendar about seven years ago. Dr. Plass develops the implications….
… Today more carbon dioxide is being generated by man’s technological processes than by volcanoes, geysers and hot springs. Every century man is increasing the carbon dioxide content of the atmosphere by 30 percent — that is, at the rate of 1.1° C in a century. It may be chance coincidence that the average temperature of the world since 1900 has risen by about this rate. But the possibility that man had a hand in the rise cannot be ignored.
Whenever the cause of the warming of the earth may be there is no doubt in Dr. Plass’ mind that we must reckon with more and more industrially generated carbon dioxide. “In a few centuries,” he warns, “the amount of carbon dioxide released into the atmosphere will be so large that it will have a profound effect on our climate.”
Even if our coal and oil reserves will be used up in 1,000 years, seventeen times the present amount of carbon dioxide in the atmosphere must be reckoned with. The introduction of nuclear energy will not make much difference. Coal and oil are still plentiful and cheap in many parts of the world, and there’s every reason to believe that both will be consumed by industry as long as it pays to do so.
I believe current predictions are on the order of 2C with doubling CO2 with longer term higher secondary increases. So bit less than 1956 model, but on the other hand the effects on climate have been obvious sooner than expected.
Overall, holds up quite well.