On the Variations of the Climate of the Geological and Historical Past and Their Causes

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Ekholm, Nils, 1901. On the Variations of the Climate of the Geological and Historical Past and Their Causes. Quarterly Journal of the Royal Meteorological Society. vol. 27. Pgs. 1-61.

Essay about this article

In 1901 the Swedish meteorologist Nils Gustaf Ekholm (1848-1923) examined the causes of changes in the Earth’s temperature over geological and historical time scales. His comprehensive review included astronomical factors such as changes in the sun and in the Earth’s orbit, and atmospheric factors such as changes in greenhouse gas concentrations and volcanic emissions. He demonstrated that the conductivity of the crust was insignificant in terms of its effect on climate and that the geothermal gradient was not a good indication of the age of the Earth. Disputing the young Earth theory of Lord Kelvin, Ekholm postulated a much older planet on which life has existed “for many thousand million years.”

Ekholm regarded variations of the carbon dioxide concentration as the principal cause of climatic variations, citing the “elaborate inquiry on this complicated phenomenon” made by his colleague Svante Arrhenius. He explained how carbon dioxide is a key player in the greenhouse effect and how this conclusion is based on the earlier work of Fourier, Pouillet, Tyndall, and others. By the most reliable estimates, a tripling of carbon dioxide levels will raise global temperatures 7 to 9 degrees Celcius . An increase in carbon dioxide will heat high latitudes more than the tropics and will create a warmer more uniform climate over the entire Earth.

According to Ekholm secular cooling of earth is the principal cause of variation in quantity of carbon dioxide in atmosphere. As the oceans sequestered great amounts of carbon into limestone and other calcium carbonate deposits the amount of carbon dioxide in the air began to diminish. Temperatures diminished as carbon dioxide diminished. A chain reaction of feedback mechanisms followed this decrease in temperature and lowered carbon dioxide production even further. Volcanic emissions, mountain uplift, and changes in sea level and plant cover produce periodical variations, involving the changing levels of carbon dioxide by feedback mechanisms, which is evident in geological history

Ekholm pointed out that over the course of a millennium the accumulation in the atmosphere of CO2 (carbonic acid) from the burning of pit coal will “undoubtedly cause a very obvious rise of the mean temperature of the Earth.” He also thought this effect could be accelerated by the “digging of deep fountains pouring out carbonic acid” or perhaps decreased “by protecting the weathering layers of silicates from the influence of the air and by ruling the growth of plants.” By such means Ekholm pointed to the grand possibility that it might someday be possible “to regulate the future climate of the Earth and consequently prevent the arrival of a new Ice Age.” In this scenario, climate warming by enhanced coal burning would be pitted against the natural changes in the Earth's orbital elements or the secular cooling of the sun. Ekholm concluded, “It is too early to judge of how far Man might be capable of thus regulating the future climate. But already the view of such a possibility seems to me so grand that I cannot help thinking that it will afford Mankind hitherto unforeseen means of evolution.”

Discussion Questions

a. What does Ekholm’s long 60-page review article tell you about the state of knowledge concerning geological and more recent climate change at the turn of the twentieth century?

b. What does Ekholm say about human influences on the climate system, including both inadvertent and purposeful influences?

c. What were the dominant concerns about climate change in his day?

Select articles citing this paper

Wright, L. J. (2002). "BiblioResearch: A bibliography of research outputs by the Department of Conservation and Land Management (and its predecessors) relating to the flora, fauna and forests of Western Australia, 1896-2001." Conservation Science Western Australia 4(2): 1-356.

Fleming, J. R. (2000). "T. C. Chamberlin, climate change, and cosmogony." Studies in History and Philosophy of Science Part B - Studies in History and Philosophy of Modern Physics 31(3): 293-308.

Keith, D.W. (2000) Geoengineering the climate: History and prospect. Annual Review of Energy and the Environment 25, pp. 245-284

Pfister, C., Brázdil, R., et al. (1999) Daily weather observations in sixteenth-century Europe. Climatic Change 43 (1), pp. 111-150

Gregori, G. P. and L. G. Gregori (1998). "Solar-terrestrial relations - a historical reminder." Acta Geodaetica et Geophysica Hungarica 33(2-4): 391-459.

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