A chemist ahead of his time

Guardian Unlimited | Life | A chemist ahead of his time: "The story starts in 1827 with the French mathematician Fourier. He coined the term 'greenhouse effect' and provided an explanation for the relatively small temperature difference between daytime and night-time on the Earth - and the development of a climate that was, among other things, suitable for human beings. Then, in 1860, British scientist John Tyndall measured the atmosphere's absorption of radioactive energy, and discovered that it was the minority gases, carbon dioxide and water vapour, that produced the greenhouse effect, not nitrogen or oxygen.

Following this, in 1896, a Swedish chemist named Svante Arrhenius asked the key question: 'Is the mean temperature of the ground in any way influenced by the presence of the heat-absorbing gases in the atmosphere?' He made the first attempt to investigate the effect doubling CO2would have on the global climate.

Using a simple physical model, he estimated that if the level of CO2 in the atmosphere doubled, the average global temperature would rise by 5-6C. That estimate made in 1896 is not so very different from most modern attempts to calculate the temperature change due to increasing CO2 levels...

"It was not until nearly 15 years after his death, that GS Callendar, in Britain, concluded - from his analysis of data collected from 200 weather stations worldwide since 1880 - that global warming was occurring.

Until around 1960, most scientists thought it implausible that humans could significantly affect average global temperatures. These days, serious evidence backs the conclusion that the Earth's climate is changing due to fossil fuel usage. Average global temperatures have risen by 0.6C over the past century and the concentration of CO2 has reached a level not seen on Earth for more than 740,000 years. It is now very likely that the doubling of CO2 levels supposed in Arrenhius's calculation back in 1896 will have occurred in another 80-90 years, unless global action to reduce emissions is brought into force."