Following is a timeline ahead of the November 29-December 10 meeting of the United Nations Framework Convention on Climate Change (UNFCCC) in Cancun, Mexico.
1827: French scientist Jean-Baptiste Fourier is the first to consider the "greenhouse effect", the phenomenon whereby atmospheric gases trap solar energy, increasing Earth's surface temperature.
1960: Climate science gets a key tool with the "Keeling Curve," a yardstick of rising carbon dioxide (CO2) levels in the atmosphere.
1988: UN sets up a scientific authority to vet the evidence on global warming, the Intergovernmental Panel on Climate Change (IPCC).
1990: First IPCC report says levels of man-made greenhouse gases are increasing in the atmosphere and predicts these will cause global warming.
1992: Rio Summit agrees to set up the UNFCCC, a vehicle for addressing climate change. The UNFCCC today has 194 parties.
1997: UNFCCC members sign the Kyoto Protocol. Under its first commitment period, industrialised countries must cut emissions of six greenhouse gases so they are 5.2 percent lower than 1990 levels by the end of 2012.
2001: The Kyoto Protocol, still in framework form, is abandoned by the United States, then the world's biggest carbon emitter. The pact is saved by the European Union (EU), which pilots an agreement on its rulebook and mechanisms, opening the way to ratification.
2005: Kyoto Protocol takes effect on February 16.
2006: China overtakes the United States as the world's No. 1 carbon emitter.
2007: 4th Assessment Report by the IPCC says evidence for global warming is "unequivocal" and forecasts warming of 1.8-4.0 degrees C (3.2-7.2 degrees F) by 2100 and an unquantifiable rise in sea levels. Nobel Peace Prize is awarded jointly to IPCC and former US vice president Al Gore, whose documentary "An Inconvenient Truth" raised climate change awareness. UNFCCC parties agree a "Bali Road Map" for negotiating a post-2012 climate treaty.
2009: UNFCCC summit in Copenhagen, intended to seal a post-2012 deal, nearly ends in disaster. To save face, a small group of leaders sets a broad goal of limiting warming to 2 C (3.6 F) and sketches financial provisions for poor countries. But it identifies no staging posts for reaching the target, nor requires emissions curbs to be binding.
2010: Climate change retreats as a political priority after the trauma of Copenhagen, economic problems in rich countries and attacks on the IPCC over flaws in the 4th Assessment Report.
Nov 24: UN's World Meteorological Organisation says greenhouse-gas concentrations reached record levels in 2009. Higher temperatures could unleash methane emissions from the Arctic, creating a vicious circle of warming.
Nov 29-Dec 10: Annual conference of the UNFCCC in Cancun sets sights on incremental approach, with progress on climate finance, technology transfer and deforestation.Reuse content