A chronology

1827:Jean-Baptiste Fourier, the French polymath, using the analogy of a greenhouse, suggests the possibility a global warming.

1863:Irish scientist John Tyndall describes how water vapour can act as a greenhouse gas.

1890s:Svante Arrhenius, a Swedish scientist, and P.C. Chamberlain in the U.S., explore the effect of carbon dioxide emission on the atmosphere. They explore the causal connection between emissions, particularly by the burning of fossil fuels, and global warming.

1890s to 1940:Average surface air temperatures increase by about 0.25 C.

1940 to 1970:The earth cools by about 0.2 C.

1957:Monitoring of temperatures on a continuous basis begins, implying the recognition of the problem of global warming.

1979:Climate change is recognised as a major issue at the first World Climate Conference. It calls on all governments "to foresee and prevent potential man-made 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 temperature which is greater than any in man's history", causing sea levels to rise by up to a metre.

1987:The warmest year on record. The 1980s turn out to be the warmest decade, with seven of the eight warmest years in history recorded up to 1990. Even the coldest years in the 1980s were warmer than the warmest years of the 1880s.

1988:The United Nations sets up an Intergovernmental Panel on Climate Change (IPCC) to analyse and report on scientific findings related to the problem.

1990:The first report of the IPCC concludes that the planet has warmed by 0.5 C in the past century. The IPCC provides the scientific basis for negotiations in the U.N. for a climate convention. Negotiations start in December.

1992:U.N. Framework Convention on Climate Change (UNFCCC) is signed by 154 nations in Rio de Janeiro, at the Earth Summit. Countries agree to set initial targets for peg emissions from industrialised countries to 1990 levels by the year 2000.

1994:The island nations of the world, organised by the Alliance of Small Island States, demand a 20 per cent reduction in emissions by the year 2005. The UNFCCC comes into force on March 21. It now has 186 Parties.

1995:Hottest year yet. In March, the Berlin Mandate is agreed by signatories at the first full meeting of the UNFCC in Berlin. Industrialised nations agree to cut emissions.

1996:At the second meeting of the Climate Change Convention, for the first time the U.S. agrees to legally binding emissions targets and sides with the IPCC against influential "sceptical" scientists. After a four-year pause, global emissions of CO2 resume steep climb, and scientists warn that most industrialised countries will not meet Rio agreement to stabilise emissions at 1990 levels by the year 2000.

1997:Kyoto Protocol is signed. It sets binding emissions cuts for industrialised nations, averaging 5.4 per cent, to be met during 2008-2012, relative to levels prevailing in 1990. It also adopts a set of "flexibility mechanisms", allowing countries to meet their targets by trading emissions permits and establishing carbon sinks. The U.S. says it will not ratify the agreement unless it sees evidence of "meaningful participation" by the developing countries.

1998:The hottest year in the hottest decade of the hottest century of the millennium. Follow-up negotiations (at COP-4) in Buenos Aires fail to resolve disputes over the Kyoto "rule book", but agree on a deadline for resolution by end-2000. COP-4 results in the Buenos Aires Plan of Action (BAPA). BAPA sets a deadline, COP-6, where Parties should reach agreement on a package of issues to give effect to the Kyoto Protocol.

2000:Scientific re-assessment of future emissions suggests that the world could warm by 6 C within a century. A series of major floods around the world raise fears that global warming is an immediate problem. In November, COP-6, held in The Hague, meets to finalise the "Kyoto rule book" but fails to reach agreement after the E.U. and the U.S. fall out. The Bush administration refuses to ratify the Kyoto Protocol.

2001:In March the U.S. refuses to participate in any emission reduction regime. COP-6 continues in Bonn in July. Agreement is reached on the means to give effect to the Kyoto treaty. The legal framework is set out in Marrakesh at COP-7.