as regards the colder regions of the earth, ages when the earth will bring forth much more abundant crops than at present, for the benefit of rapidly propagating mankind." (p. 63) At this time, the accepted consensus explanation is that, historically, orbital forcing has set the timing for ice ages, with CO2 acting as an essential amplifying feedback. However, CO2 releases since the industrial revolution have increased CO2 to a level not found since 10 to 15 million years ago, when the global average surface temperature was up to warmer than now and almost all ice had melted, raising world sea-levels to about 100 feet (30 m.) higher than today's. Arrhenius estimated based on the CO2 levels at his time, that reducing levels by 0.62–0.55 would decrease temperatures by 4–5 °C (Celsius) and an increase of 2.5 to 3 times of CO2 would cause a temperature rise of 8–9 °C in the Arctic. In his book Worlds in the Making he described the "hot-house" theory of the atmosphere. Works 1884, Recherches sur la conductibilité galvanique des électrolytes, doctoral dissertation, Stockholm, Royal publishing house, P. A. Norstedt & Söner, 155 pages. 1896a, Ueber den Einfluss des Atmosphärischen Kohlensäurengehalts auf die Temperatur der Erdoberfläche, in the Proceedings of the Royal Swedish Academy of Science, Stockholm 1896, Volume 22, I N. 1, pages 1–101. 1896b, On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground, London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science (fifth series), April 1896. vol 41, pages 237–275. 1901a, Ueber die Wärmeabsorption durch Kohlensäure, Annalen der Physik, Vol 4, 1901, pages 690–705. 1901b, Über Die Wärmeabsorption Durch Kohlensäure Und Ihren Einfluss Auf Die Temperatur Der Erdoberfläche. Abstract of the proceedings of the Royal Academy of Science, 58, 25–58. Arrhenius, Svante. Die Verbreitung des Lebens im Weltenraum. Die Umschau, Frankfurt a. M., 7, 1903, 481–486. 1906, Die vermutliche Ursache der Klimaschwankungen, Meddelanden från K. Vetenskapsakademiens Nobelinstitut, Vol 1 No 2, pages 1–10 1908, Das Werden der Welten (Worlds in the making; the evolution of the universe), Academic Publishing House, Leipzig, 208 pages. See also Activation energy Arrhenius acid Arrhenius law Arrhenius plot Néel–Arrhenius theory History of climate change science James Croll Eunice Newton Foote George Perkins Marsh Milutin Milanković Greta Thunberg – climate activist and distant relative of Arrhenius Viscosity models for mixtures References Sources Further reading External links "Enter the Anthropocene: Climate Science