[6] In the 1960s, Charles David Keeling reliably measured the level of carbon dioxide present in the air showing it was increasing and that, according to the greenhouse hypothesis, it was sufficient to cause significant global warming.

At the age of three, Arrhenius taught himself to read without the encouragement of his parents and, by watching his father's addition of numbers in his account books, became an arithmetical prodigy.

[citation needed] At age eight, he entered the local cathedral school, starting in the fifth grade, distinguishing himself in physics and mathematics, and graduating as the youngest and most able student in 1876.

The most important idea in the dissertation was his explanation of the fact that solid crystalline salts disassociate into paired charged particles when dissolved, for which he would win the 1903 Nobel Prize in Chemistry.

Arrhenius's explanation was that in forming a solution, the salt disassociates into charged particles that Michael Faraday had given the name ions many years earlier.

[12][13][14] The dissertation did not impress the professors at Uppsala, but Arrhenius sent it to a number of scientists in Europe who were developing the new science of physical chemistry, such as Rudolf Clausius, Wilhelm Ostwald, and Jacobus Henricus van 't Hoff.

Arrhenius declined, however, as he preferred to stay in Sweden-Norway for a while (his father was very ill and would die in 1885) and had received an appointment at Uppsala.

In 1885, Arrhenius next received a travel grant from the Swedish Academy of Sciences, which enabled him to study with Ostwald in Riga (now in Latvia), with Friedrich Kohlrausch in Würzburg, Germany, with Ludwig Boltzmann in Graz, Austria, and with Jacobus Henricus van 't Hoff in Amsterdam.

He used his positions to arrange prizes for his friends (Jacobus van 't Hoff, Wilhelm Ostwald, Theodore Richards) and to attempt to deny them to his enemies (Paul Ehrlich, Walther Nernst, Dmitri Mendeleev).

In 1904, he delivered at the University of California a course of lectures, the object of which was to illustrate the application of the methods of physical chemistry to the study of the theory of toxins and antitoxins, and which were published in 1907 under the title Immunochemistry.

[23][24] He also turned his attention to geology (the origin of ice ages), astronomy, physical cosmology, and astrophysics, accounting for the birth of the Solar System by interstellar collision.

He was a board member for the Swedish Society for Racial Hygiene (founded 1909), which endorsed mendelism at the time, and contributed to the topic of contraceptives around 1910.

[7][31][32] These calculations led him to conclude that human-caused CO2 emissions, from fossil-fuel burning and other combustion processes, are large enough to cause global warming.

Arrhenius wanted to determine whether greenhouse gases could contribute to the explanation of the temperature variation between glacial and inter-glacial periods.

is the augmentation of the temperature, in other words the change in the rate of heating Earth's surface (radiative forcing), which is measured in Watts per square meter.

[37] Based on information from his colleague Arvid Högbom,[38] Arrhenius was the first person to predict that emissions of carbon dioxide from the burning of fossil fuels and other combustion processes were large enough to cause global warming.

In his calculation Arrhenius included the feedback from changes in water vapor as well as latitudinal effects, but he omitted clouds, convection of heat upward in the atmosphere, and other essential factors.

He later wrote Världarnas utveckling (1906) (German: Das Werden der Welten [1907], English: Worlds in the Making [1908]) directed at a general audience, where he suggested that the human emission of CO2 would be strong enough to prevent the world from entering a new ice age, and that a warmer earth would be needed to feed the rapidly increasing population: 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.

[39][40] 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 6 °C (11 °F) warmer than now and almost all ice had melted, raising world sea-levels to about 100 feet (30 m.) higher than today's.