A greenhouse timeline 1827:French polymath Jean-Baptiste Fourier suggests the existence of an atmospheric effect keeping the Earth warmer than it would otherwise be. He also uses the analogy of a greenhouse 1863:Irish scientist John Tyndall publishes paper describing how water vapour can be a greenhouse gas 1890s: Swedish scientist Svante Arrhenius and an American, T.C. Chamberlain, independently consider the problems that might be caused by a CO2 building up in the atmosphere. Both scientists realise that the burning of fossil fuels could lead to global warming, but neither suspects the process might already have started INSERT: The key papers that started the whole greenhouse debate are: http://webserver.lemoyne.edu/faculty/giunta/Arrhenius.html And T. C. Chamberlin (Thomas): Chamberlin, T. C. An attempt to frame a working hypothesis of the cause of glacial periods on an atmospheric basis (continued) J. Geology 7 667 685 1899 Chamberlin, T. C. An attempt to frame a working hypothesis of the cause of glacial periods on an atmospheric basis (III) J. Geology 7 751 787 1899 Chamberlin was from Wisconsin, was president of the UW-Madison from 1887-1892 and has a building on the UW campus named afer him. http://en.wikipedia.org/wiki/Thomas_Chrowder_Chamberlin From Arrhenius: "In order to get the temperature of the ice age between the 40th and 50th parallels, the carbonic acid in the air should sink to 0.62--0.55 of its present value (lowering of temperature 4°-5°C.)." The minimum CO2 (aka carbonic acid) level during the ice age was about 0.6 of the value in 1898. We know this by measurements of CO2 in ice bubbles, not from calculations as to the effect of removing CO2 from the atmosphere. Neither of them were considering increased CO2 to be a problem. Arrhenius thought it would be beneficial, but was more concerned with the question of what made planets habitable and less so on the geologic time scale. Chamberlin, as you might guess from the titles, was interested in climate change through geologic time and was advancing CO2 variations as a mechanism. The first person I know of who approached anthropogenic CO2-induced climate change as a problem was Callendar, in the 1930's. END OF INSERT 1890s to 1940:Average surface air temperatures increase by about 0.25 °C. Some scientist see American dustbowl as a sign of the greenhouse effect at work 1940 to 1970:Worldwide cooling of 0.2 °C; scientific interest in greenhouse effect wanes. Some climatologists predict a new ice age 1957:US oceanographer Roger Revelle warns that humans were conducting a "large-scale geophysical experiment" on the planet by releasing greenhouse gases. Colleague David Keeling sets up first continuous monitoring of CO2 levels in the atmosphere. Immediately Keeling finds regular year-on-year rise 1970s: Series of studies by US Department of Energy crank up concern about future global warming 1979:First World Climate Conference adopts climate change as major issue and calls on governments "to foresee and prevent potential manmade changes in climate." 1985:First major international conference on the greenhouse effect, at Villach, Austria, warns that greenhouse gases will "in the first half of the next century cause a rise of global mean temerature which is greater than any in man's history." Says this could cause sea levels to rise by up to a metre. Also warns that gases other than CO2, such as methane, ozone, CFCs and nitrous oxide, will contribute to warming 1987:Warmest year on record. The 1980s turn out to be the warmest decade, with seven of the eight warmest years up to 1990. The coldest years in the 1980s were warmer than the warmest years of the 1880s 1988:Global warming attracts worldwide headlines after scientists at Congressional hearings in Washington DC blame major US drought on its influence. Meeting of climate scientists in Toronto subsequently calls for 20 per cent cuts in global CO2 emissions by year 2005. UN sets up the Intergovernmental Panel on Climate Change (IPCC) to analyse and report on scientific findings 1990:IPCC's first report finds that planet has warmed by 0.5 °C in the past century. Warns that only strong measures to halt rising greenhouse gas emissions will prevent serious global warming. Provides scientific clout for UN negotiations for a climate convention. Negotiations begin after December UN General Assembly 1991:Mount Pinatubo erupts in the Philippines, throwing debris into the stratosphere that shields Earth from solar energy and helps interrupt the warming trend. Average temperatures drop for two years before rising again. Scientists point out that this event shows how sensitive global temperatures are to disruption 1992:Climate Change Convention, signed by 154 nations in Rio, agrees to prevent "dangerous" warming from greenhouse gases and sets initial target of pegging emissions from industrialised countries to 1990 levels by year 2000 1994:Alliance of Small Island States from all over the world--many of whom fear they will disappear beneath the waves as sea levels rise -- adopt demand for 20 per cent cuts in emissions by the year 2005. This, they say, will cap sea-level rise at 20 centimetres 1995:Hottest year yet. In March, first full meeting of convention signatories in Berlin, agrees Berlin Mandate. Industrialised nations agree on the need to negotiate real cuts in their emissions, to be concluded by the end of 1997 In November, the IPCC casts caution to the winds and agrees that current warming "is unlikely to be entirely natural in origin" and that "the balance of evidence suggests a discernible human influence on global climate". Report predicts that, under a "business as usual" scenario, global warming by the year 2100 will be in the range of 1 degree C to 3.5 °C 1996:At second meeting of the Climate Change Convention, the US agrees for the first time to legally binding emissions targets and sides with the IPCC against influential "sceptical" scientists After four-year pause, global emissions of CO2 resume steep climb. Growing warnings that most industrialised countries will not meet Rio agreement to stabilise emissions at 1990 levels by the year 2000 Early 1997:Republican-dominated Congress backtracks on Berlin Mandate, and states that it will only ratify a new agreement limiting US emissions if developing countries also accept limits. US Administration calls for "flexibility measures" such as emissions trading. Meanwhile European Union agrees to propose 15 per cent cuts for industrialised nations 2000: Global Warming Accelerating, U.S. Study Finds. Writing in the March 1 issue of Geophysical Research Letters, Thomas Karl, director of the center, said there was only a one-in-20 chance that the record high temperatures in 1997 and 1998 were simply unusual events -- as opposed to being a turning point in global climate. WASHINGTON (Reuters) - Global warming is not only real but it is accelerating, U.S. government researchers say. In the past 25 years alone, average global temperatures have started zooming up at a rate that works out to four degrees Fahrenheit per century, the team at the National Climate Data Center, part of the National Oceanic and Atmospheric Administration (NOAA), said. 2001: Increase in Greenhouse Gases Seen From Space LONDON (Reuters) - Scientists dispelled any lingering doubts about the increase of greenhouse gases in the atmosphere Wednesday with new evidence from satellites orbiting the Earth. Until now researchers have depended on ground-based measurements and theoretical models to gauge the change in greenhouse gases, believed by scientists to be the cause of global warming and major climate disruption. New sets of data taken 27 years apart from two satellites orbiting the Earth have now provided the first observational evidence from space of a rise in greenhouse gases. ``We've seen greenhouse gas increases that we can link to a change in outgoing long-wave radiation, which is believed to force the climate response,'' said Dr. Helen Brindley, an atmospheric physicist at Imperial College in London. By comparing the two sets of data, Brindley and her colleagues have shown a change in greenhouse gas emissions from Earth over 27 years which is consistent with ground-based measurements. Real Differences Over 27 Years The comparison of the data, reported in the science journal Nature, shows real differences over 27 years in the outgoing long-wave radiation which can only be due to greenhouse gases. The scientists compared data for a region over the Pacific Ocean and the entire globe to calculate the differences in the levels of atmospheric methane, carbon dioxide (CO2), ozone and chlorofluorocarbons. --