June 1988: At the World Conference on the Changing Atmosphere in Toronto, politicians and scientists conclude that "humanity is conducting an unintended, uncontrolled, globally pervasive experiment whose ultimate consequences could be second only to a global nuclear war." The conference recommends reducing carbon dioxide emissions 20 per cent by 2005.
November 1988: The Intergovernmental Panel on Climate Change (IPCC) has its first meeting in Geneva. The IPCC, which now consists of 2,500 leading scientists and experts on climate change, is given a mandate to assess the state of scientific knowledge on climate change, evaluate its impacts and come up with realistic solutions.
August 1990: The IPCC publishes its First Assessment Report, which concludes the increasing accumulation of human-made greenhouse gases in the atmosphere would "enhance the greenhouse effect, resulting on average in an additional warming of the Earth's surface" unless measures are adopted to limit the emissions of these gases.
June 1992: At the Rio Earth Summit, 154 signatories to the United Nations Framework Convention on Climate Change (UNFCCC) agree to stabilize "greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous interference with the climate system." Developed countries accept responsibility for the overwhelming majority of emissions and "aim to stabilize" those emissions at 1990 levels by the year 2000.
October 1993: In Canada, the federal Liberals' election platform includes a promise to reduce greenhouse gas emissions 20 per cent below 1988 levels by 2005.
March 1995: The first Conference of the Parties, made up of signatories to the UNFCCC, acknowledges that the UNFCCC is inadequate without country-specific commitments and agrees to negotiate emission-reduction targets for industrialized countries.
December 1995: The IPCC releases its Second Assessment Report, which concludes: "The balance of evidence suggests a discernible human influence on global climate."
July 1996: In Geneva, at the second Conference of the Parties, the U.S. agrees to legally binding targets and timetables to reduce emissions, but also proposes an international emissions-trading scheme. More than 100 other countries also agree to develop targets.
March 1997: At a meeting in Geneva, European environment ministers propose industrialized nations reduce their emissions 15 per cent below 1990 levels by 2010. The chair of the IPCC states that all nations, developed and developing, would eventually be required to reduce emissions in order to stabilize the atmosphere.
December 1997: More than 150 countries sign the Kyoto Protocol, which binds 38 industrialized countries (called Annex 1 countries) to reduce greenhouse gas emissions by an average of 5.2 per cent below 1990 levels for the period of 2008-2012. To make it law, at least 55 countries must ratify the Protocol and 55 per cent of Annex 1 emissions must be covered. Though details are not finalized, the agreement includes "flexibility" mechanisms that would allow industrialized nations to get credit for actions to reduce greenhouse gas emissions in other countries. Canada is successful in including "carbon sinks" within the agreement, enabling countries to count carbon stored in forests and soils toward their emission-reduction targets.
October 1999: German Chancellor Gerhard Schroeder challenges Annex 1 nations to ratify the Protocol by 2002. The EU says it is "ready and willing" to do so. Canada and the U.S. oppose a deadline.
November 2000: The talks at the sixth Conference of the Parties in The Hague collapse. Similar to previous Conferences of the Parties in 1998 and 1999, Canada joins the U.S., Japan and Australia in trying to exploit loopholes in Kyoto's "flexibility" mechanisms. The European Union and many small island states, meanwhile, try to restrict credit to actions that actually reduce emissions.
January-May 2001: The IPCC releases its Third Assessment Report, which states "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities." Seventeen national and regional academies of science state: "The work of the ... IPCC represents the consensus of the international science community on climate change science. We recognize IPCC as the world's most reliable source of information ... and endorse its method of achieving this consensus."
March 2001: Two months after his inauguration, U.S. President George W. Bush announces his country's withdrawal from the Kyoto Protocol.
June 2001: All nations except for the U.S. agree on the principles of implementing the Kyoto Protocol at a meeting in Bonn. To reach agreement, Canada drops its demand that credit be given for nuclear sales to developing countries, but succeeds in getting generous credits for agricultural and forest sinks.
December 2001: In Marrakech, Morocco, the final elements of the Kyoto Protocol are hammered out. The U.S., Canada, Japan and Australia force the EU to accept major concessions in order to reach the final agreement.
December 2002: Following a three-month national debate, Canada ratifies the Kyoto Protocol.
February 16, 2005: The Kyoto Protocol becomes international law after Russian ratification pushes the emissions of ratified Annex 1 countries over the 55 per cent mark.
May 2005: Bonn hosts the first official negotiating meeting after Kyoto comes into force, where discussion begins on the second phase of the Kyoto Protocol, post-2012.
November-December 2005: The first Meeting of the Parties occurs in Montreal, where it is agreed that a second phase of the Kyoto Protocol will be negotiated. No deadline for finalizing the amended Protocol is agreed to.
February-November 2007: The IPCC releases its Fourth Assessment Report, calling anthropogenic climate change "unequivocal" and stating that "most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations."
December 2007: Bali hosts the annual UN negotiations and Parties agree to a road map that will steer governments through a round of talks aimed at ensuring that a new agreement will be concluded during the Copenhagen summit at the end of 2009. Negotiators also agree on an aggressive negotiating schedule and multiple intersessional negotiating meetings are held throughout 2008 and 2009. Progress to reach the self-imposed deadline of December 2009 is glacial.
July 2009: G8 countries agree that a limit of 2ºC of average global warming should not be exceeded. To reach this goal, global greenhouse gas emissions should be reduced by at least 50 per cent by 2050 and emissions from developed countries should be reduced by 80 per cent or more.
Nov 2009: The Copenhagen Diagnosis is released, providing new evidence to suggest that several important aspects of climate change are occurring at a rate even greater than predicted by the IPCC's Fourth Assessment Report in 2007. Authors conclude that global emissions must peak and then decline rapidly within the next five to 10 years if global warming is to be limited to a maximum of 2ºC above pre-industrial levels.
December 2009: The UN climate summit in Copenhagen represents the deadline for a fair, ambitious and binding global agreement on climate change.