page_title: History of climate change science
section_title: First calculations of greenhouse effect, 1896
hierarchical_section_title: History of climate change science / First calculations of greenhouse effect, 1896
caption_attribution_description: Deutsch: Svante Arrhenius (* 19. Februar 1859 auf Gut Wik bei Uppsala; † 2. Oktober 1927 in Stockholm)
context_page_description: The history of the scientific discovery of climate change began in the early 19th century when ice ages and other natural changes in paleoclimate were first suspected and the natural greenhouse effect first identified. In the late 19th century, scientists first argued that human emissions of greenhouse gases could change the climate. Many other theories of climate change were advanced, involving forces from volcanism to solar variation. In the 1960s, the evidence for the warming effect of carbon dioxide gas became increasingly convincing. Some scientists also pointed out that human activities that generated atmospheric aerosols could have cooling effects as well.
  During the 1970s, scientific opinion increasingly favored the warming viewpoint. By the 1990s, as a result of improving fidelity of computer models and observational work confirming the Milankovitch theory of the ice ages, a consensus position formed: greenhouse gases were deeply involved in most climate changes and human-caused emissions were bringing discernible global warming. Since the 1990s, scientific research on climate change has included multiple disciplines and has expanded.
context_section_description: By the late 1890s, Samuel Pierpoint Langley along with Frank W. Very had attempted to determine the surface temperature of the Moon by measuring infrared radiation leaving the Moon and reaching the Earth. The angle of the Moon in the sky when a scientist took a measurement determined how much CO
  2 and water vapor the Moon's radiation had to pass through to reach the Earth's surface, resulting in weaker measurements when the Moon was low in the sky.  This result was unsurprising given that scientists had known about infrared radiation absorption for decades.
  In 1896 Svante Arrhenius used Langley's observations of increased infrared absorption where Moon rays pass through the atmosphere at a low angle, encountering more carbon dioxide (CO
  2), to estimate an atmospheric cooling effect from a future decrease of CO
  2.  He realized that the cooler atmosphere would hold less water vapor (another greenhouse gas) and calculated the additional cooling effect. He also realized the cooling would increase snow and ice cover at high latitudes, making the planet reflect more sunlight and thus further cool down, as James Croll had hypothesized. Overall Arrhenius calculated that cutting CO
  2 in half would suffice to produce an ice age. He further calculated that a doubling of atmospheric CO
  2 would give a total warming of 5–6 degrees Celsius.
  Further, Arrhenius' colleague Arvid Högbom, who was quoted in length in Arrhenius' 1896 study On the Influence of Carbonic Acid in the Air upon the Temperature of the Earth had been attempting to quantify natural sources of emissions of CO
  2 for purposes of understanding the global carbon cycle.  Högbom found that estimated carbon production from industrial sources in the 1890s (mainly coal burning) was comparable with the natural sources.
  Arrhenius saw that this human emission of carbon would eventually lead to warming. However, because of the relatively low rate of CO
  2 production in 1896, Arrhenius thought the warming would take thousands of years, and he expected it would be beneficial to humanity.
  In 1899 Thomas Chrowder Chamberlin developed at length the idea that changes in climate could result from changes in the concentration of atmospheric carbon dioxide. Chamberlin wrote in his 1899 book, An Attempt to Frame a Working Hypothesis of the Cause of Glacial Periods on an Atmospheric Basis:
  Previous advocacy of an atmospheric hypothesis, — The general doctrine that the glacial periods may have been due to a change in the atmospheric content of carbon dioxide is not new. It was urged by Tyndall a half century ago and has been urged by others since. Recently it has been very effectively advocated by Dr. Arrhenius, who has taken a great step in advance of his predecessors in reducing his conclusions to definite quantitative terms deduced from observational data. [..] The functions of carbon dioxide. — By the investigations of Tyndall, Lecher and Pretner, Keller, Roentgen, and Arrhenius, it has been shown that the carbon dioxide and water vapor of the atmosphere have remarkable power of absorbing and temporarily retaining heat rays, while the oxygen, nitrogen, and argon of the atmosphere possess this power in a feeble degree only. It follows that the effect of the carbon dioxide and water vapor is to blanket the earth with a thermally absorbent envelope. [..] The general results assignable to a greatly increased or a greatly reduced quantity of atmospheric carbon dioxide and water may be summarized as follows:
  a. An increase, by causing a larger absorption of the sun's radiant energy, raises the average temperature, while a reduction lowers it. The estimate of Dr. Arrhenius, based upon an elaborate mathematical discussion of the observations of Professor Langley, is that an increase of the carbon dioxide to the amount of two or three times the present content would elevate the average temperature 8° or 9° C. and would bring on a mild climate analogous to that which prevailed in the Middle Tertiary age.  On the other hand, a reduction of the quantity of carbon dioxide in the atmosphere to an amount 
caption: In 1896 Svante Arrhenius calculated the effect of a doubling atmospheric carbon dioxide to be an increase in surface temperatures of 5–6 degrees Celsius.
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