Global warming
History of the science
Svante Arrhenius noted that water vapour in air continuously varied, but carbon dioxide (CO 2) was determined by long term geological processes. At the end of an ice age, warming from increased CO 2 would increase the amount of water vapour, amplifying its effect in a feedback process. In 1896, he published the first climate model of its kind, showing that halving of CO 2 could have produced the drop in temperature initiating the ice age. Arrhenius calculated the temperature increase expected from doubling CO 2 to be around 5–6 °C (9.0–10.8 °F). Other scientists were initially sceptical and believed the greenhouse effect to be saturated so that adding more CO 2 would make no difference. Experts thought climate would be self-regulating. From 1938 Guy Stewart Callendar published evidence that climate was warming and CO 2 levels increasing, but his calculations met the same objections.
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