| 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 and
Summary.) This list of milestones includes some of the major influences
external to the science itself. Following it is a list
of other external influences.
1800-1870
Level of carbon dioxide gas (CO2) in the atmosphere,
as later measured in ancient ice, is about 290 ppm (parts per million).
Mean global temperature (1850-1890) is roughly 13.6°C.
First Industrial Revolution. Coal, railroads, and land clearing speed
up greenhouse gas emissions, while better agriculture and sanitation speed
up population growth.
1824
Fourier proposes 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 CO2.
=>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 CO2 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
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.
=>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 CO2 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 CO2 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 CO2
in the Earth's atmosphere and detects an annual rise.
=>CO2 greenhouse
The CO2 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 CO2 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 CO2 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 U.S. 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 CO2.
=>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
Deep-sea cores show a dominating influence from 100,000-year Milankovitch
orbital changes, emphasizing the role of feedbacks. =>Climate cycles
Deforestation and other ecosystem changes are recognized as major factors
in the future of the climate. =>Biosphere
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 CO2 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 production.
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 CO2 and temperature
went up and down together through past ice ages, pointing to powerful
feedbacks. =>CO2
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 persuade 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 global heating caused by increase in greenhouse gases. =>Rapid change
1992
Conference in Rio de Janeiro produces UN Framework Convention on Climate
Change, but U.S. blocks calls for serious action. =>International
Study of ancient climates reveals climate sensitivity to CO2 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 "fingerprint" 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 U.S. 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 of Sciences panel. =>Modern temp's
Mann's "hockey stick" data indicates current warming is historically unprecedented.
=>Modern temp's
Ramanathan detects massive "brown cloud" of aerosols over South
Asia. =>Aerosols
2000
Global Climate Coalition dissolves as many corporations grapple
with threat of warming, but oil lobby convinces US administration to ignore
the problem. =>Public opinion
Variety of studies emphasize variability and importance of biological
feedbacks in carbon cycle, liable to accelerate warming. =>Biosphere
2001
Warming observed in ocean basins; match with computer models gives a
clear signature of greenhouse effect warming. =>Models (GCMs)
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
National Academy of Sciences panel sees a "paradigm shift" in scientific
recognition of the risk of abrupt (decade-scale) climate change. =>Rapid change
Bonn meeting, with participation of most countries but not US, develops
mechanisms for working towards Kyoto targets. =>International
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
European Union initiates "cap and trade" market to reduce emissions.
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 that 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 CO2.
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 point out that even if all greenhouse gas emissions could be halted immediately, global temperature will remain elevated for millennia. =>CO2
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
Studies find total carbon emitted determines global temperature; the "budget" for avoiding dangerous heating is mostly used up.=>International
Copenhagen conference fails to negotiate binding agreements: end of hopes of avoiding severe future climate change. =>International
2011
Reaction to nuclear reactor disaster at Fukushima (Japan) ends hopes for a renaissance of nuclear power.
2012
"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
Rise of methane in atmosphere accelerates, threatening dangerous feedbacks. =>Other gases
Paris Agreement: nearly all nations pledge to set their own targets for greenhouse gas cuts and to report their progress. =>International
2016
Solar electricity and wind power become economically competitive with fossil fuels in some regions.
Fossil fuel CO2 emissions stop climbing exponentially, slow rise continues.
2018
IPCC report on 1.5°C warming says that to avoid dangerous climate change, the world’s greenhouse gas emissions must be in sharp decline by 2030. =>International.
2019
Increasing disasters (tropical cyclones, wildfires, etc.) join scientists' warnings to spur public demonstrations and civil disobedience.=>Impacts =>Public opinion
2021
Sixth IPCC report warns that catastrophic outcomes cannot be ruled out. =>Impacts
Glasgow conference spurs pledges to restrict emissions — not enough to avoid dangerous climate change, but risk of catastrophic change is reduced. =>International.
2022
Democrats in U.S. Congress pass legislation providing subsidies to reduce the nation's greenhouse gas emissions. =>Government
2024
Mean global temperature (five-year average) is 14.9°C, the highest
in tens of thousands of years. Level of CO2 in the atmosphere is 425 ppm, the highest in millions of years.
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