Timeline of milestones in climate change science and public and political responses to the science 2005 - 1800*  
   
2005  
Kyoto treaty goes into effect. The European Union and thirty-five industrialised countries, excluding the US and Australia, are now legally bound to reduce or limit their greenhouse gas emissions. Japan, Western Europe and regional US entities accelerate work to retard emissions.
Leaders of G8 meet in Gleneagles Scotland and after several days of intense discussions are still divided and make no real progress in the fight against climate change.
Level of CO2 in the atmosphere reaches 380 ppm. 		 
2004  
In controversy over temperature data covering past millennium most scientists conclude climate was variable (perhaps because of changes in the sun) but not comparable to post-1980 warming.  
2003  
Variety of studies increase concern that collapse of ice sheets (West Antarctica, perhaps Greenland) can raise sea levels faster than most had believed.
Deadly summer heat wave in Europe accelerates divergence between European and US public opinion. 		 
2002  
Studies find surprisingly strong "global dimming," due to pollution, has retarded arrival of greenhouse warming, but dimming is now decreasing.  
2001  
COP VI(2) meeting in Bonn, Germany, with participation of most countries but not US, develops mechanisms for working towards Kyoto targets; something that eluded them at COP VI the previous year in The Hague, Netherlands.
Third IPCC report states baldly that global warming, unprecedented since the end of last ice age, is "very likely," with possible severe surprises. The report provides substantial information on the expected impacts from different levels of future warming. Warming above 1-2 degrees is predicted to result in rapidly escalating damages, the extent of which is qualitatively different from lower temperatures. Publication of this report brings about an effective end of debate among all but a few scientists.
National Academy panel sees a "paradigm shift." in scientific recognition of the risk of abrupt climate change (decade-scale).
Warming observed in ocean basins; match with computer models gives a clear signature of greenhouse effect warming.		  
2000  
Global Climate Coalition dissolves as many corporations grapple with threat of warming, but oil lobby convinces US administration to deny problem.
Variety of studies emphasize variability and importance of biological feedbacks in carbon cycle, liable to accelerate warming.		  
1998 – 2000  
COPs IV, V & VI take place in Buenos Aires, Argentina, Bonn, Germany and The Hague, Netherlands. Participants work towards rules for implementing the Kyoto Protocol.  
1999  
Criticism that satellite measurements show no warming are dismissed by National Academy Panel.
Ramanathan detects massive "brown cloud" of aerosols from South Asia. 		 
1998  
The warmest year on record, globally averaged (1995, 1997, 2001-2004 neared the same level). Borehole data confirm extraordinary modern warming trend.
Qualms about arbitrariness in computer models diminish as teams model ice-age climate and dispense with special adjustments to reproduce current climate.		  
1997  
COP III in Kyoto, Japan produces Kyoto Protocol, setting new targets to reduce greenhouse gas emissions, if enough nations sign onto a treaty. 1990 greenhouse gas emissions would be cut by 5% between 2008 and 2012. Though 5% is a global target, different countries have different targets. The European Union's target is an 8% cut (Germany committed to a 25% cut and the U.K. to 15%). The United States had a target of 7%, while Canada had a target of 6%. Both Canada and the United States signed the Kyoto Protocol, thereby promising to cut their greenhouse gas emissions.  
1996  
COP II in Geneva, Switzerland - in the first meeting after the IPCC's second report, the countries belonging to the Rio Convention said, "climate change represented a danger to humanity."  
1995  
COP I in Berlin, Germany – the first annual meeting, Conference of Parties (COP), of the countries that ratified the Rio Convention. Participants reviewed the adequacy of the Rio Convention's goal of stabilizing greenhouse gas emissions.
Second IPCC report detects "signature" of human-caused greenhouse effect warming; declares that serious warming is likely in the coming century.
Reports of the breaking up of Antarctic ice sheets and other signs of actual current warming in polar-regions begin affecting public opinion.		  
1993  
Greenland ice cores suggest that great climate changes (at least on a regional scale) can occur in the space of a single decade.  
1992  
2nd Earth Conference in Rio de Janeiro produces UN Framework Convention on Climate Change, calling for 1990 GHG emissions to be stabilised by 2000. Both Canada and the United States signed and ratified this convention. Importantly, former U.S. president George Bush negotiated an agreement to allow developing nations to increase emissions, the reason they are not included in the Kyoto Protocol. The treaty is legally binding on countries that ratified it.
Study of ancient climates reveals climate sensitivity in same range as predicted independently by computer models. 		 
1991  
Mt. Pinatubo explodes; Hansen predicts cooling pattern, verifying (by 1995) computer models of aerosol effects.
Global warming sceptics emphasize studies indicating that a significant part of 20th-century temperature changes were due to solar influences. (The correlation would fail in the following decade.)
Studies from 55 million years ago show possibility of eruption of methane from the seabed with enormous self-sustained warming. 		 
1990  
First IPCC (Intergovernmental Panel on Climate Change) report says world has been warming, caused by human activity, and future warming seems likely. Industry lobbyists and some scientists dispute the tentative conclusions.  
1989  
Fossil-fuel and other industries form Global Climate Coalition in US to lobby politicians and convince the media and public that climate science is too uncertain to justify action.  
1988  
News media coverage of global warming leaps upward following record heat and droughts plus testimony by Hansen.
Toronto conference on the changing atmosphere calls for strict, specific limits on greenhouse gas emissions (20% on1988 levels by 2005).
Ice-core and biology studies confirm living ecosystems make climate feedback by way of methane, which could accelerate global warming.
Intergovernmental Panel on Climate Change (IPCC) is established bringing together scientists from the world’s governments.
Level of CO2 in the atmosphere reaches 350 ppm		  
1987  
Montreal Protocol of the Vienna Convention imposes international restrictions on emission of ozone-destroying gases.  
1985  
Villach conference declares consensus among experts that some global warming seems inevitable, calls on governments to consider international agreements to restrict emissions.
Antarctic ice cores show that CO2 and temperature went up and down together through past ice ages.
Broecker speculates that a reorganization of North Atlantic Ocean circulation can bring swift and radical climate change. 		 
1983  
Reports from U.S. National Academy of Sciences and Environmental Protection Agency spark conflict, as greenhouse warming becomes prominent in mainstream politics.  
1982  
Greenland ice cores reveal drastic temperature oscillations in the space of a century in the distant past.
Strong global warming since mid-1970s is reported, with 1981 the warmest year on record.		  
1981  
Hansen and others show that sulphate aerosols can significantly cool the climate, raising confidence in models showing future greenhouse warming.
Some scientists predict greenhouse warming “signal” should be visible by about the year 2000. 		 
1979  
Second oil "energy crisis." Strengthened environmental movement encourages renewable energy sources, inhibits nuclear energy growth.
U.S. National Academy of Sciences report finds it highly credible that doubling CO2 will bring 1.5-4.5°C global warming.
World Climate Research Programme launched to coordinate international research. 		 
1978  
Attempts to coordinate climate research in U.S. end with an inadequate National Climate Program Act, accompanied by rapid but temporary growth in funding.  
1977  
Scientific opinion tends to converge on global warming, not cooling, as the chief climate risk in next century.  
1976  

Studies show that CFCs (1975) and methane and ozone (1976) can make a serious contribution to the greenhouse effect.
Deep-sea cores show a dominating influence from 100,000-year Milankovitch orbital changes, emphasizing the role of feedbacks.

Deforestation and other ecosystem changes are recognized as major factors in the future of the climate.
Eddy shows that there were prolonged periods without sunspots in past centuries, corresponding to cold periods.

  
1975  
Concern about environmental effects of airplanes leads to investigations of trace gases in the stratosphere and discovery of danger to ozone layer.
Manabe and collaborators produce complex but plausible computer models which show a temperature rise of several degrees for doubled CO2 levels.		  
1974  
Serious droughts and other unusual weather since 1972 increase scientific and public concern about climate change, with cooling from aerosols suspected to be as likely as warming; journalists talk of ice age.  
1972  
Ice cores and other evidence show big climate shifts in the past between relatively stable modes in the space of a thousand years or so, especially around 11,000 years ago.
1st Earth summit in Stockholm, Sweden at which world leaders announced their intention to hold a gathering every ten years to determine the health of the planet.		  
1971  
SMIC (Study of Man's Impact on Climate) conference of leading scientists reports a danger of rapid and serious global change caused by humans, calls for an organized research effort
Mariner 9 spacecraft finds a great dust storm warming the atmosphere of Mars, plus indications of a radically different climate in the past. 		 
1970  
First Earth Day. Environmental movement attains strong influence, spreads concern about global degradation.
Creation of U.S. National Oceanic and Atmospheric Administration, the world's leading funder of climate research.
Aerosols from human activity are shown to be increasing swiftly. Bryson claims they counteract global warming and may bring serious cooling. 		 
1969  
Budyko and Sellers present models of catastrophic ice-albedo feedbacks. (The albedo is a measure of reflectivity of a surface or body.)
Nimbus III satellite begins to provide comprehensive global atmospheric temperature measurements.		  
1968  
Studies suggest a possibility of collapse of Antarctic ice sheets, which would raise sea levels catastrophically.  
1967  
International Global Atmospheric Research Program established, mainly to gather data for better short-range weather prediction, but including climate.
Manabe and Wetherald make a convincing calculation that doubling CO2 levels would raise world temperatures a couple of degrees. 		 
1966  
Emiliani's analysis of deep-sea cores shows the timing of ice ages was set by small orbital shifts, suggesting that the climate system is sensitive to small changes  
1965  
Boulder, Colorado meeting on causes of climate change, in which Lorenz and others point out the chaotic nature of climate system and the possibility of sudden shifts.  
1963  
Calculations suggest that feedback with water vapour could make the climate acutely sensitive to changes in CO2 level.  
1960  
Downturn of global temperatures since the early 1940s is reported and throws climate science into confusion.
Keeling accurately measures CO2 in the Earth's atmosphere and detects an annual rise. The level is now 315 ppm.		  
1958  
Telescope studies show a greenhouse effect raises temperature of the atmosphere of Venus far above the boiling point of water, indeed to upwards of 600°K, around the melting point of lead.  
1957  
Launch of Soviet Sputnik satellite. Cold War concerns support 1957-58 International Geophysical Year, bringing new funding and coordination to climate studies.
Revelle finds that CO2 produced by humans will not be readily absorbed by the oceans. He discovered that seawater did not retain all the extra CO2 it took up. A careful look showed that the surface layer of the sea could not really absorb much gas — barely one-tenth the amount a naïve calculation would have predicted. 		 
1956  
Ewing and Donn propose the first prediction of the possibility of disastrous climate change in a feedback model for quick ice age onset.
While the model was subsequently rejected, their theory was nevertheless important. It was picked up by journalists who warned that ice sheets might advance within the next few hundred years and so, for the first time, gave the public a respectable scientific backing for images of disastrous climate change. The discussions also pushed scientists to inspect data for new kinds of information.
Plass, for example produced a thorough set of one-dimensional computations that showed that adding or subtracting CO2 could seriously affect the world's radiation balance. From that point on, nobody could dismiss the theory with the simple old objections, even though fatal flaws were subsequently found in his theory.		  
1955  
Norman Phillips produces the first realistic computer model of the global atmosphere on a computer with only 5K of memory. His model was quickly hailed as a "classic experiment" — the first true General Circulation Model (GCM) and resulted in government funding for a long-term project.  
1945  
U.S. Office of Naval Research begins generous funding of many fields of science, some of which happen to be useful for understanding climate change.  
1938  
Callendar, an English engineer and amateur climatologist, is the first person to study global temperature change systematically and thoroughly. He argues that CO2 greenhouse global warming is underway, reviving interest in the question.  
1930s  
Global warming trend since late 19th century reported in the US and North Atlantic region.  
1870-1910  
During the second Industrial Revolution, fertilizers and other chemicals, electricity, and public health further accelerate population growth.  
1897  
American geologist, Chamberlin, demonstrates that the only way to understand climate was to understand almost everything about the planet together — not just the air but the oceans, the volcanoes bringing gases from the deep interior, the chemistry of weathered minerals, and more. Chamberlin's novel hypothesis was that ice ages might follow a self-oscillating cycle driven by feedbacks involving CO2  
1896  
A Swede, Arrhenius, publishes first calculation of global warming from human emissions of CO2.  
1862  
Physicist John Tyndall becomes the first person to describe the key to climate change. He discovered in his laboratory that certain gases, including water vapour and carbon dioxide (CO2), are opaque to heat rays. He understood that such gases high in the air help keep our planet warm by interfering with escaping radiation.  
1800-1870  
During the first Industrial Revolution, coal, railroads, and land clearing speed up greenhouse gas emission, while better agriculture and sanitation speed up population growth.
Measurements - taken in ancient ice during the 1970s - of the level of carbon dioxide gas (CO2) in the atmosphere during this period estimate it to be about 290 ppm (parts per million).		  
   

* Summarised from a website entitled “The Discovery of Global Warming” created by Spencer Weart. Visit the site for complete timeline and many other excellent climate change science resources.

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