A closer look at the history of climate change:
1750 Before Industrial Revolution, atmosphere holds 280 parts per million of heat-trapping carbon dioxide (CO 2), later research determines.
1859 Successful hard-rock drilling for oil in Titusville, Pennsylvania, inaugurates the age of intensive oil use in world history.
1888 In Sudbury, Ont., a nickel-smelting complex opens. It is destined to be one of the greatest single sources of air pollution and acid rain in North America.
1894-95 Attempting to explain the ice ages, Swedish scientist Svante Arrhenius theorizes that changes in carbon-dioxide levels in the atmosphere may alter our climate. "It is unbelievable," Arrhenius notes, "that so trifling a matter has cost me a full year."
1905 The word smog, an amalgam of smoke and fog, is coined in England. It achieves wide currency only with the photochemical smogs of motorized cities after 1950.
1938 British engineer G.S. Callendar studies historic temperature and atmospheric CO 2 concentrations and concludes that the world is warming, fuelled by greenhouse gases.
1948 Al-Ghawar, the world's largest oil field, is discovered in Saudi Arabia. The find leads to a drop in energy prices and a burst of energy intensification in the Western world. By 1950, global energy consumption surpasses 20 billion megawatts, reflecting the rapid expansion of fossil-fuel use.
1955 U.S. scientist Charles Keeling finds atmospheric CO 2 has risen to 315 parts per million.
1957 American oceanographer Roger Revelle - later dubbed "the grandfather of the greenhouse effect" - concludes that we are undertaking a "large-scale geophysical experiment" by releasing CO 2 into the environment. (Mr. Revelle goes on to teach at Harvard University, where his views have a significant effect on his students, who include a young Al Gore.)
1970 New York's Fifth Avenue is shut down as 20 million Americans celebrate the first Earth Day and the arrival of a global environmental movement.
1979 University of Toronto meteorologist Kenneth Hare co-ordinates a summary paper for the first World Climate Conference in Geneva. The reaction from politicians? "Little or none," Mr. Hare later comments.
1980 The World Climate Research Programme begins its work coordinating international efforts to determine the effect of human activities on climate.
1983 Two American scientific reports predict that the Northwest Passage will open to ships during the summer and the Hudson Bay lowlands will become a "food basket" within a decade.
1985 Sharp seasonal reductions in the Earth's stratospheric ozone layer, which protects life from harmful ultraviolet radiation, are detected by British scientists.
1987 In the Montreal Protocol, 24 nations agree to limit the production of chlorofluorocarbons (CFCs). Subsequent accords tighten the agreements, slowing the deterioration of stratospheric ozone.
1988 Scientists at an international climate conference in Toronto announce "warming due to greenhouse gases has begun," and call for a 20-per-cent reduction in CO 2 emissions by 2005. The eighties become the hottest decade on record.
1989 G7 leaders recognize global warming as a "serious threat" and vow to develop "determined and concerted" policies to safeguard the environment.
1989 Bill McKibben publishes The End of Nature, the first major popular book on climate change.
1990 Global energy use surpasses 80 billion megawatts, reflecting the spread of high-energy societies beyond Europe and North America. Newly elected U.S. president George W. Bush warns against global-warming policies that affect economic growth. The Global Climate Coalition, an industry group including Exxon and Shell, call the President's speech "very strong."
1990 700 scientists and environmental specialists reach consensus at the Intergovernmental Panel on Climate Change (IPCC) that the planet is facing unprecedented warming and countries should take immediate steps to reduce greenhouse gases.
1991 Fearful that their nations will disappear under the waves as seas rise, the 15 member countries of the South Pacific Forum petition industrialized nations to cut emissions of greenhouse gases. A strategy memo from the U.S.-based Global Climate Coalition identifies the goal of the industry-funded group (which includes Exxon and Shell) as to "reposition global warming as theory rather than fact."
1992 At the United Nations' Earth Summit in Rio de Janeiro, more than 150 countries agree to set individual non-binding limits on greenhouse-gas emissions.
1994 Scientists report a 65-to-70-per-cent decrease in the ozone layer over the Faraday research base in Antarctica, further evidence of a long-term erosion of this section of the Earth's atmosphere.
1995 The Intergovernmental Panel on Climate Change declares that "the balance of evidence suggests a discernible human influence on global climate" and predicts global temperatures will rise by up to 3.5 degrees Celsius by the end of the 20th century.
1997 Industrialized nations, including Canada, agree to legally binding emissions cuts under the Kyoto Protocol. The U.S. refuses to ratify the Kyoto accord without "meaningful participation" from developing nations.
1998 A 200-square-kilometre chunk of ice splits from the Larsen B ice shelf in Antarctica. Warming temperatures are blamed.
1999 George Monbiot, British commentator and author of the climate change book Heat, offers a stinging indictment of air travel and its massive carbon footprint: "Flying across the Atlantic is as unacceptable, in terms of its impact on human well-being, as child abuse," he writes in a column in The Guardian.
2000 Robins and barn swallows appear for the first time in Sachs Harbour, NWT, one of Canada's most northern communities. "We can't read the weather like we used to," an Inuk resident says. "And it's changing our way of life."
2001 A 2,600-page report from the Intergovernmental Panel on Climate Change states that the Earth is warming faster that at any time during the past 1,000 years and that concentrations of CO2 possibly have not been higher for 20 million years.
2002 Canada ratifies the Kyoto Protocol in Parliament.
2004 CO 2 reaches record 379 parts per million; Russia gives crucial ratification to Kyoto Protocol.
2005 Kyoto Protocol takes effect Feb. 16.
Sources: Encyclopedia Britannica, The Associated Press