Timeline (Milestones

Here are gathered in chronological sequence the most important events in the history of climate change science. (For a narrative see the Introduction: summary history.) This list of milestones includes major influences external to the science itself. Following it is a list of other external influences.

1800-1870

Level of carbon dioxide gas (CO 2 ) in the atmosphere, as later measured in ancient ice, is about 290 ppm (parts per million).

Mean global temperature (1850-1890) is roughly 13.7°C.

First Industrial Revolution. Coal, railroads, and land clearing speed up greenhouse gas emission, while better agriculture and sanitation speed up population growth.

1824

Fourier calculates that the Earth would be far colder if it lacked an atmosphere. => Simple models

1859

Tyndall demonstrates that some gases block infrared radiation, and notes that changes in the concentration of the gases could bring climate change. => Other gases

1879

International Meteorological Organization begins to compile and standardize global weather data, including temperature. => International

1896

Arrhenius publishes first calculation of global warming from human emissions of CO 2 . => Simple models

1897

Chamberlin produces a model for global carbon exchange including feedbacks. => Simple models

1870-1910

Second Industrial Revolution. Fertilizers and other chemicals, electricity, and public health further accelerate growth.

1914-1918

World War I; governments learn to mobilize and control industrial societies.

1920-1925

Opening of Texas and Persian Gulf oil fields inaugurates era of cheap energy.

1930s

Global warming trend since late 19th century reported. => Modern temp's

Milankovitch proposes orbital changes as the cause of ice ages. => Climate cycles

1938

Callendar argues that CO 2 greenhouse global warming is underway, reviving interest in the question. => CO2 greenhouse

1939-1945

World War II. Military grand strategy is largely driven by a struggle to control oil fields.

1945

US Office of Naval Research begins generous funding of many fields of science, some of which happen to be useful for understanding climate change. => Government

1955

Phillips produces a convincing computer model of the global atmosphere. => Models (GCMs)

1956

Ewing and Donn offer a feedback model for abrupt climate change. => Simple models

Plass calculates that adding CO 2 to the atmosphere will have a significant effect on the radiation balance. => Radiation math

1957

Launch of Soviet Sputnik satellite. Cold War concerns support 1957-58 International Geophysical Year, bringing new funding and coordination to climate studies. => International

Revelle finds that CO 2 produced by humans will not be readily absorbed by the oceans. => CO2 greenhouse

1958

Telescope studies show a greenhouse effect raises temperature of the atmosphere of Venus far above the boiling point of water. => Venus & Mars

1960

Mitchell reports downturn of global temperatures since the early 1940s. => Modern temp's

Keeling accurately measures CO 2 in the Earth's atmosphere and detects an annual rise. => CO2 greenhouse The level is 315 ppm. Mean global temperature (five-year average) is 13.9°C.

1962

Cuban Missile Crisis, peak of the Cold War.

1963

Calculations suggest that feedback with water vapor could make the climate acutely sensitive to changes in CO 2 level. => Radiation math

First meeting of experts concerned with global warming warns that a rise in sea level is likely, with "immense flooding" of shorelines. => Impacts

1965

Boulder, Colorado meeting on causes of climate change: Lorenz and others point out the chaotic nature of the climate system and the possibility of sudden shifts. => Chaos theory

1966

Emiliani's analysis of deep-sea cores and Broecker's analysis of ancient corals show that the timing of ice ages was set by small orbital shifts, suggesting that the climate system is sensitive to small perturbations. => Climate cycles

1967

International Global Atmospheric Research Program established, mainly to gather data for better short-range weather prediction, but including climate. => International

Manabe and Wetherald make a convincing calculation that doubling CO 2 would raise world temperatures a couple of degrees. => Radiation math

1968

Studies suggest a possibility of collapse of Antarctic ice sheets, which would raise sea levels catastrophically. => sea rise, ice, floods

1969

Astronauts walk on the Moon, and people perceive the Earth as a fragile whole. => Public opinion

Budyko and Sellers present models of catastrophic ice-albedo feedbacks. => Simple models

Nimbus III satellite begins to provide comprehensive global atmospheric temperature measurements. => Government

1970

First Earth Day. Environmental movement attains strong influence, spreads concern about global degradation. => Public opinion

Creation of US National Oceanic and Atmospheric Administration, the world's leading funder of climate research. => Government

Aerosols from human activity are shown to be increasing swiftly. Bryson claims they counteract global warming and may bring serious cooling. => Aerosols

1971

SMIC conference of leading scientists reports a danger of rapid and serious global change caused by humans, calls for an organized research effort. => International

Mariner 9 spacecraft finds a great dust storm warming the atmosphere of Mars, plus indications of a radically different climate in the past. => Venus & Mars

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. => Rapid change

Droughts in Africa, Ukraine, India cause world food crisis, spreading fears about climate change. => Public opinion

1973

Oil embargo and price rise bring first "energy crisis". => Government

1974

Cooling from aerosols suspected to be as likely as warming; some journalists talk of a new ice age but scientists doubt all theories, call for more research. => Public opinion

1975

Warnings about environmental effects of airplanes lead to investigations of trace gases in the stratosphere and discovery of danger to ozone layer. => Other gases

Manabe and collaborators produce complex but plausible computer models which show a temperature rise of a few degrees for doubled CO 2. => Models (GCMs)

1976

Studies show that CFCs (1975) and also methane and ozone (1976) can make a serious contribution to the greenhouse effect. => Other gases

=>

=>

Eddy shows that there were prolonged periods without sunspots in past centuries, corresponding to cold periods. => Solar variation

1977

Scientific opinion tends to converge on global warming, not cooling, as the chief climate risk in the next century. => Public opinion

1978

Attempts to coordinate climate research in US end with an inadequate National Climate Program Act, accompanied by rapid but temporary growth in funding. => Government

1979

Second oil "energy crisis." Strengthened environmental movement encourages renewable energy sources, inhibits nuclear energy growth. => Public opinion

US National Academy of Sciences report finds it highly credible that doubling CO 2 will bring 1.5-4.5°C global warming . => Models (GCMs)

World Climate Research Programme launched to coordinate international research . => International

1981

Election of Reagan brings backlash against environmental movement to power. Political conservatism is linked to skepticism about global warming. => Government

IBM Personal Computer introduced. Advanced economies are increasingly delinked from energy.

Hansen and others show that sulfate aerosols can significantly cool the climate, raising confidence in models that incorporate aerosols and show future greenhouse warming. => Aerosols

Some scientists predict greenhouse warming "signal" should become visible around the year 2000. => Modern temp's

1982

Greenland ice cores reveal drastic temperature oscillations in the space of a century in the distant past. => Rapid change

Strong global warming since mid-1970s is reported, with 1981 the warmest year on record. => Modern temp's

1983

Reports from US National Academy of Sciences and Environmental Protection Agency spark conflict; greenhouse warming becomes a factor in mainstream politics. => Government

Speculation over catastrophic climate change following a nuclear war, or a dinosaur-killing asteroid strike, promote realization of the atmosphere's fragility. => World winter

1985

Ramanathan and collaborators announce that global warming may come twice as fast as expected, from rise of methane and other trace greenhouse gases. => Other gases

Villach Conference declares consensus among experts that some global warming seems inevitable, calls on governments to consider international agreements to restrict emissions. => International

Antarctic ice cores show that CO 2 and temperature went up and down together through past ice ages, pointing to powerful feedbacks. => CO 2

Broecker speculates that a reorganization of North Atlantic Ocean circulation can bring swift and radical climate change. => The oceans

1986

Meltdown of reactor at Chernobyl (Soviet Union) cripples plans to replace fossil fuels with nuclear power.



1987

Montreal Protocol of the Vienna Convention imposes international restrictions on emission of ozone-destroying gases. => International

1988

News media coverage of global warming leaps upward following record heat and droughts plus statements by Hansen. => Public opinion

Toronto conference calls for strict, specific limits on greenhouse gas emissions; UK Prime Minister Thatcher is first major leader to call for action. => International

Ice-core and biology studies confirm living ecosystems give climate feedback by way of methane, which could accelerate global warming. => Other gases

Intergovernmental Panel on Climate Change (IPCC) is established. => International

1989

Fossil-fuel and other U.S. industries form Global Climate Coalition to tell politicians and the public that climate science is too uncertain to justify action. => Public opinion

1990

First IPCC report says world has been warming and future warming seems likely. => International

1991

Mt. Pinatubo explodes; Hansen predicts cooling pattern, verifying (by 1995) computer models of aerosol effects. => Aerosols

Global warming skeptics claim that 20th-century temperature changes followed from solar influences. (The solar-climate correlation would fail in the following decade.) => Solar variation

Geologists discover massive extinction event 55 million years ago, associated with tremendous warming caused by increase in greenhouse gases. => Rapid change

1992

Conference in Rio de Janeiro produces UN Framework Convention on Climate Change, but US blocks calls for serious action. => International

Study of ancient climates reveals climate sensitivity to CO 2 in same range as predicted independently by computer models. => Models (GCMs)

1993

Greenland ice cores suggest that great climate changes (at least on a regional scale) can occur in the space of a single decade. => Rapid change

1995

Second IPCC report detects "signature" of human-caused greenhouse effect warming, declares that serious warming is likely in the coming century. => International

Reports of the breaking up of Antarctic ice shelves and other signs of actual current warming in polar regions begin affecting public opinion. => Public opinion

1997

Toyota introduces Prius in Japan, first mass-market electric hybrid car; swift progress in large wind turbines, solar electricity, and other energy alternatives.

International conference produces Kyoto Protocol, setting targets for industrialized nations to reduce greenhouse gas emissions if enough nations sign onto a treaty (rejected by US Senate in advance). => International

1998

A "Super El Niño" makes this an exceptionally warm year, equaled in later years but not clearly exceeded until 2014. Borehole data confirm extraordinary warming trend. => Modern temp's

Qualms about arbitrariness in computer models diminish as teams model ice-age climate and dispense with special adjustments to reproduce current climate. => Models (GCMs)

1999

Criticism that satellite measurements show no warming are dismissed by National Academy Panel. => Modern temp's

Ramanathan detects massive "brown cloud" of aerosols from South Asia. => Aerosols

2000

Global Climate Coalition dissolves as many corporations grapple with threat of warming, but oil lobby convinces US administration to deny problem. => Public opinion

Variety of studies emphasize variability and importance of biological feedbacks in carbon cycle, liable to accelerate warming. => Biosphere

2001

Third IPCC report states baldly that global warming, unprecedented since the end of the last ice age, is "very likely," with highly damaging future impacts => Impacts and possible severe surprises. Effective end of debate among all but a few scientists. => International

Bonn meeting, with participation of most countries but not US, develops mechanisms for working towards Kyoto targets. => International

National Academy panel sees a "paradigm shift" in scientific recognition of the risk of abrupt (decade-scale) climate change. => Rapid change

Warming observed in ocean basins; match with computer models gives a clear signature of greenhouse effect warming. => Models (GCMs)

2002

Studies find surprisingly strong "global dimming," due to pollution, has retarded arrival of greenhouse warming, but dimming is now decreasing. => Aerosols

2003

Numerous observations raise concern that collapse of ice sheets (West Antarctica, Greenland) can raise sea level faster than most had believed. => sea rise, ice, floods

Deadly summer heat wave in Europe accelerates divergence between European and US public opinion. => Public opinion

2004

First major books, movie, and art work featuring global warming appear. => Public opinion

2005

Kyoto treaty goes into effect, signed by major industrial nations except US. Work to retard emissions accelerates in Japan, Western Europe, US regional governments and corporations.

=> International

Hurricane Katrina and other major tropical storms spur debate over impact of global warming on storm intensity. => sea rise, ice, floods

2006

In longstanding "hockey stick" controversy, scientists conclude post-1980 global warming was unprecedented for centuries or more. => Modern temp's The rise could not be attributed to changes in solar energy. => Solar variation

"An Inconvenient Truth" documentary persuades many but sharpens political polarization. => Public opinion

China overtakes the United States as the world’s biggest emitter of CO 2 .

2007

Fourth IPCC report warns that serious effects of warming have become evident; cost of reducing emissions would be far less than the damage they will cause. => International

Greenland and Antarctic ice sheets and Arctic Ocean sea-ice cover found to be shrinking faster than expected. => sea rise, ice, floods

2008

Climate scientists (although not the public) recognize that even if all greenhouse gas emissions could be halted immediately, global warming will continue for millennia. => CO 2

2009

Many experts warn that damage from climate change is arriving at a faster pace than was anticipated just a few years earlier. => International

Excerpts from stolen e-mails of climate scientists fuel public skepticism. => Public opinion

Copenhagen conference fails to negotiate binding agreements: end of hopes of avoiding dangerous future climate change. => International

2011

Reaction to nuclear reactor disaster at Fukushima (Japan) ends hopes for a renaissance of nuclear power.

2012

Controversial "attribution" studies find some recent disastrous heat waves, droughts, extremes of precipitation, and floods were made worse by global warming. => Impacts

2013

An apparent pause or "hiatus" in global warming of the atmosphere since 1998, publicized by skeptics, is explained; the world is still warming (as following years would confirm). => Modern temp's

2015

Researchers find collapse of West Antarctic ice sheet may be irreversible, bringing meters of sea-level rise over future centuries. => sea rise, ice, floods



Paris Agreement: nearly all nations pledge to set their own targets for greenhouse gas cuts and to report their progress. => International

Solar electricity and wind power become economically competitive with fossil fuels in some regions.

2019 News of disasters (tropical cyclones, wildfires, etc.) and intensified scientific warnings raise concern, especially among younger people, and spur public demonstrations and civil disobedience. => Impacts => Public opinion