1827 French scientist Jean-Baptiste Fourier compares the warming effect of the atmosphere to a greenhouse.

1863 John Tyndall, an Irish scientist, shows how water vapour in the atmosphere can act as a greenhouse gas by trapping heat.

1890s Swedish scientist Svante Arrhenius suggests that burning fossil fuels may lead to a build-up of carbon dioxide in the atmosphere, which could exacerbate the greenhouse effect.

1957 David Keeling, a US scientist, begins to monitor carbon dioxide on a long-term basis and soon finds a year-on-year rise.

1979 First World Climate Conference highlights the possibility of global warming.

1985 The first world conference on the greenhouse effect is held at Villach in Austria.

1987 Warmest year on record.

1988 US congressional hearings blame major drought in the United States on the influence of global warming. The World Meteorological Organisation set up the Intergovernmental Panel on Climate Change (IPCC).

1990 First report of the IPCC finds that the planet has warmed by 0.5C on average since the start of the 20th century.

1992 Climate Change Convention signed in Rio by 154 nations sets initial targets to reduce the scale of carbon dioxide emissions, based on emissions in 1990.

1995 The hottest year to date.

1997 Kyoto protocol agrees binding cuts in emissions but US says it will not ratify unless Third World countries are included.

1998 Hottest year on record, in the hottest decade.

2001 George Bush abandons Kyoto, saying the science is uncertain. IPCC publishes its third assessment report. Link strengthened between man-made emissions of carbon dioxide and global warming.

2002 The EU and Japan ratify Kyoto but Russia delays. The world experiences second hottest year on record.

2003 Heatwave kills thousands across Europe. Scientists link it directly with global warming.

2004 Russia signs up to Kyoto, so it can now come into force in 2005.

2005 Second warmest year on record globally. Kyoto protocol comes into force. Economist Nicholas Stern publishes his report saying that we cannot afford to do nothing about climate change. In August, New Orleans is devastated by Hurricane Katrina.

2006 The IPCC confirms that global warming is real and that man-made emissions of carbon dioxide are at least partly responsible. Former US vice-president Al Gore wins an Oscar for the film An Inconvenient Truth, warning about global warming.

(By Steve Connor, The Independent, 14/03/2007)