Adaptation background

In the 1820s Fourier calculated that an object the size of the Earth, and at its distance from the Sun, should be considerably colder than the planet actually is if warmed only by the effects of incoming solar radiation. He examined various possible sources of the additional observed heat in articles published in 1824[15] and 1827.[16] While he ultimately suggested that interstellar radiation might be responsible for a large portion of the additional warmth, Fourier's consideration of the possibility that the Earth's atmosphere might act as an insulator of some kind is widely recognized as the first proposal of what is now known as the greenhouse effect.[17]

Between 10,000 and 100,000 calculations later, Arrhenius had some rough, but useful, results that he published in 1896. If CO2 levels halved, he concluded, the the Earth's surface temperature would fall by 4-5C. There was a flipside to his calculations: doubling CO2 levels would trigger a rise of about 5-6C. He thought it would take milleniato see a 50% rise in CO2 -

n 1938, nine years after Arrhenius had died a Nobel prizewinner for his work on ionic solutions, English engineer Guy Callendargave the greenhouse theory a boost. An expert on steam technology, he took up meteorology as a sideline and became interested in suggestions of a warming trend. Callendarpieced together temperature measurements from the 19th century onwards and saw an appreciable rise. He went on to check CO2 over the same period and discovered levels had increased about 10% in 100 years. The warming was probably due to the higher levels of CO2. At the time, computer models were suggesting modest increases, perhaps 2C in hundreds of years.

In 1953 Plass told Time Magazine of his work on the effects of CO2 from industrial sources as a greenhouse gas, and the potential implications of an increased concentration of carbon dioxide in the atmosphere for global warming. He said "At its present rate of increase, the CO2 in the atmosphere will raise the earth's average temperature 1.5° Fahrenheit every 100 years. ... for centuries to come, if man's industrial growth continues, the earth's climate will continue to grow warmer.“From 1956 onwards he published a series of papers on the topic, partly based on advanced calculations of the absorption of infrared radiation, and he made use of early electronic computers. Plass predicted that a doubling of CO2 would warm the planet by 3.6°C, that CO2 levels in 2000 would be 30% higher than in 1900 and that the planet would be about 1°C warmer in 2000 than in 1900.

Charles Keeling spent two years taking measurements in Antarctica and above the Mauna Loa volcano in Hawaii but reported that even in this short period (1958-1961)

, CO2 levels had risen. He concluded that the oceans weren't absorbing greenhouse gases being pumped out by industry. Instead, emissions were driving levels of CO2 higher. "It was a seminal discovery. For the first time, scientists knew that the oceans weren't going to absorb all this carbon dioxide," says Mike Hulme at the Tyndall Centre for climate change research at the University of East Anglia.