1824: French scientist Jean-Baptiste Fourier describes the greenhouse effect: how the atmosphere traps solar energy to increase earth's surface temperature.

		Photo by NOAA Charles Keeling, who in the 1950s was the first person to measure rising levels of carbon dioxide in the air.

1859: Irish scientist John Tyndall performs experiments that identify water vapor and carbon dioxide as greenhouse gasses

1896: Swedish chemist Svante Arrhenius describes how burning fossil fuels produces carbon dioxide -- the first suggestion that human activity produces greenhouse gasses.

1958: U.S. Scientist Charles Keeling makes the first direct measurement of atmospheric carbon dioxide at Mauna Loa in Hawaii; he discovers a yearly rise in atmospheric carbon dioxide.

1979: A landmark report by National Academy of Sciences connects the greenhouse effect to global warming. The report warns that "a wait and see policy may mean waiting until it's too late."

1988: The United Nations Environment Program creates the Intergovernmental Panel on Climate Change and the World Meteorological Organization to vet scientific knowledge of global warming.

1990: The first IPCC report says that levels of manmade greenhouse gases are increasing, and that this will cause global warming. It documents a 0.3- to 0.6-degree Celsius increase in average temperatures over the past 100 years.

June 1992: The U.N. Conference on the Environment in Rio de Janeiro creates the U.N. Framework Convention on Climate Change. Representatives from 178 nations attend. Two dozen industrialized nations sign an accord requiring them to submit reports describing policies for reducing emissions to 1990 levels.

March 1995: U.N. Framework Convention on Climate Change Conference of Parties meets for first time in Berlin. Delegates from 170 nations approve a plan called the Berlin mandate to set specific targets for reducing emissions in the 21^st century. They also accept a principle of "joint implementation" in which industrialized countries offset emissions by financing cuts in greenhouse gasses in developing countries.

1995: The second IPCC assessment is released. It notes a 10 to 25 cm rise in sea levels over past decade, and says that variations in global temperature suggest "a discernible human influence on global climate."

July 1996: U.S. Undersecretary of State for Global Affairs Timothy Wirth outlines a proposal at the UNFCC conference in Geneva that calls for legally binding benchmarks for industrialized nations for greenhouse gas reductions.

Dec. 1997: The Kyoto Protocol is adopted at the third Conference of Parties in Kyoto. The U.S. does not sign the treaty. The treaty requires developed countries to reduce their greenhouse gas emissions below specific levels between 2008 and 2012; the cuts add up to a total of at least 5 percent below 1990 levels. The U.S. would be required to reduce emissions by 7 percent, Europe by 8 percent, Japan by 6 percent. Fleshing out the treaty is left to further negotiations.

Nov. 1998: Negotiators from 160 countries agree to set rules for enforcing Kyoto protocol by late 2000.

Nov. 2000: A two-week conference at the Hague fails to produce an agreement on measures to fight global warming. The U.S. and EU cannot agree on necessary measures.

Nov. 2001: Negotiators from 160 countries agree on a treaty strengthening Kyoto by setting mandatory emissions reduction targets and establishing an enforcement mechanism. The treaty requires 40 industrialized countries to reduce emissions by 5.2 percent below 1990 levels by 2012. The U.S. again doesn't sign.

2001: The IPCC's third report is issued. It declares evidence for manmade global warming "incontrovertible" although the effects on climate are hard to pin down.  It also states that the 1990s were the warmest decade since records have been kept. (Cosmos, Frontline)

2002: On the Antarctic peninsula, the Larsen B ice shelf -- bigger than Rhode Island -- collapses into the sea.

2003: A deadly summer heat wave in Europe kills more than 30,000 people

2004: The International Energy Agency says China is now the worlds' second-biggest greenhouse gas emitter after the U.S.

Nov 2004: After Russia ratifies the Kyoto treaty -- the 19^th country to do so -- the treaty becomes legally binding.

Feb. 2005: The Kyoto Protocol takes effect.

		Photo flickr user Juampe Lopez Former Vice President Al Gore giving his climate change slideshow presentation made famous in the film “An Inconvenient Truth” .

2005: Awareness and concern about global warming rises in the U.S. after a tough storm season, including Katrina.

Dec. 2005: Industrialized nations that are part of Kyoto agree to set talks to produce a new set of binding limits to take effect in 2012, after Kyoto expires.

2006: Former Vice President Al Gore's documentary "An Inconvenient Truth" is released.

2006: California adopts a plan to reduce greenhouse gas emissions  to 1990 levels by 2020. The state files a lawsuit against six carmakers for contributions to global warming.

2006: NASA's top climatologist, James Hansen, accuses the Bush administration of censoring what he can say about climate change.

2007: China surpasses the U.S. in greenhouse gas emissions.

Feb. 2007: An IPCC report says that it is extremely likely that human activities are contributing to global warming in a way that will be difficult to reverse.

April 2007: An IPCC report says with "high confidence" that human activities are responsible for global warming and that the warming is changing the ecosystem and plant and animal behavior.

May 2007: An IPCC report says that the world needs to significantly cut greenhouse gasses, and offers measures for doing so.

Oct. 2007: Al Gore and the IPCC share the 2007 Nobel Peace Prize for efforts to spread awareness of climate change.

		Photo by Flickr User bass_nroll The IPCC final assesment paper finds that the world will have to end its growth of carbon emissions within seven years and become free of carbon-emitting technologies in four decades to avoid widespread extinctions, flooding, loss of wetlands, deaths from heat waves, and other consequences

Nov. 2007: The IPCC releases final assessment paper. Report finds that the world will have to end its growth of carbon emissions within seven years and become free of carbon-emitting technologies in four decades to avoid widespread extinctions, flooding, loss of wetlands, deaths from heat waves, and other consequences.

December 2007: The conference of parties to the UNFCCC meets in Bali, Indonesia, to launch negotiations for a roadmap for a new post-Kyoto climate change treaty. After much anger directed at the U.S., negotiators cut a last-minute deal and agree to negotiate a treaty by December 2009.

2008: A 160-square-mile section of the Wilkins Ice Shelf breaks from the coast of Antarctica.

April 2008: Negotiators in Bangkok, Thailand, begin the first formal talks after the Bali conference to negotiate a new climate treaty.

December 2009: Scheduled date for the 15^th annual conference of the parties to the UNFCCC. Due date to negotiate a new climate change treaty.

-- Sources: The Washington Post, Cosmos; UK Met office, Frontline, The Austin Chronicle