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.
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 13.7°C.
First Industrial Revolution. Coal, railroads, and land clearing speed
up greenhouse gas emission, while better agriculture and sanitation speed
up population growth.
Fourier calculates that the Earth would be far colder if it lacked
an atmosphere. =>Simple models
Tyndall discovers that some gases block infrared radiation. He suggests
that changes in the concentration of the gases could bring climate change.
Arrhenius publishes first calculation of global warming from human emissions
of CO2. =>Simple models
Chamberlin produces a model for global carbon exchange including feedbacks.
Second Industrial Revolution. Fertilizers and other chemicals, electricity,
and public health further accelerate growth.
World War I; governments learn to mobilize and control
Opening of Texas and Persian Gulf oil fields inaugurates era of cheap
Global warming trend since late 19th century reported. =>Modern temp's
Milankovitch proposes orbital changes as the cause of ice ages. =>Climate cycles
Callendar argues that CO2 greenhouse global warming
is underway, reviving interest in the question. =>CO2 greenhouse
World War II. Military grand strategy is largely driven by a struggle to control
US Office of Naval Research begins generous funding of many fields of
science, some of which happen to be useful for understanding climate change.
Ewing and Donn offer a feedback model for quick ice age onset. =>Simple models
Phillips produces a somewhat realistic computer model of the global
atmosphere. =>Models (GCMs)
Plass calculates that adding CO2 to the atmosphere
will have a significant effect on the radiation balance. =>Radiation math
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
Telescope studies show a greenhouse effect raises temperature of the atmosphere
of Venus far above the boiling point of water. =>Venus & Mars
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 level
is 315 ppm. Mean global temperature (five-year average) is 13.9°C.
Cuban Missile Crisis, peak of the Cold War.
Calculations suggest that feedback with water vapor could make the climate
acutely sensitive to changes in CO2 level. =>Radiation math
Boulder, Colo. meeting on causes of climate change: Lorenz and others
point out the chaotic nature of climate system and the possibility of
sudden shifts. =>Chaos theory
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 changes. =>Climate cycles
International Global Atmospheric Research Program established, mainly
to gather data for better short-range weather prediction, but including
Manabe and Wetherald make a convincing calculation
that doubling CO2 would raise world temperatures a couple of degrees. =>Radiation math
Studies suggest a possibility of collapse of Antarctic ice sheets, which
would raise sea levels catastrophically. =>Sea rise & ice
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.
Nimbus III satellite begins to provide comprehensive global atmospheric
temperature measurements. =>Government
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
SMIC 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.=>Venus & Mars
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
Oil embargo and price rise bring first "energy crisis". =>Government
Serious droughts since 1972 increase concern about climate, with cooling
from aerosols suspected to be as likely as warming; scientists are doubtful
as journalists talk of a new ice age.=>Public opinion
Warnings 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.
Deep-sea cores show a dominating influence from 100,000-year Milankovitch
orbital changes, emphasizing the role of feedbacks. =>Climate cycles
Studies show that CFCs (1975) and also methane and ozone (1976) can make
a serious contribution to the greenhouse effect. =>Other gases
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
Scientific opinion tends to converge on global warming, not cooling, as
the chief climate risk in next century. =>Public opinion
Attempts to coordinate climate research in US end with an inadequate
National Climate Program Act, accompanied by rapid but temporary growth
in funding. =>Government
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
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 showing future greenhouse warming.
Some scientists predict greenhouse warming "signal" should
be visible by about the year 2000. =>Modern temp's
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
Reports from US National Academy of Sciences and Environmental Protection
Agency spark conflict, as greenhouse warming becomes prominent in mainstream
Speculation over catastrophic climate change following a nuclear war, or a dinosaur-killing asteroid strike, promote realization of the atmosphere's fragility. =>World
Ramanathan and collaborators announce that global warming may come
twice as fast as expected, from rise of methane and other trace greenhouse
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
biological and geochemical feedbacks. =>CO2
Broecker speculates that a reorganization of North Atlantic Ocean circulation
can bring swift and radical climate change. =>The oceans
Meltdown of reactor at Chernobyl (Soviet Union) cripples plans to replace fossil fuels with nuclear power.
Montreal Protocol of the Vienna Convention imposes international restrictions
on emission of ozone-destroying gases. =>International
News media coverage of global warming leaps upward following record heat
and droughts plus testimony 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
Ice-core and biology studies confirm living ecosystems give climate
feedback by way of methane, which could accelerate global warming.
Intergovernmental Panel on Climate Change (IPCC) is established. =>International
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
First IPCC report says world has been warming and future warming seems
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
Studies from 55 million years ago show possibility of eruption of methane
from the seabed with enormous self-sustained warming. =>Rapid change
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 in same range as
predicted independently by computer models. =>Models (GCMs)
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
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.
Toyota introduces Prius in Japan, first mass-market electric
hybrid car; swift progress in large wind turbines 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).
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)
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
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
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 climate change (decade-scale). =>Rapid change
Warming observed in ocean basins; match with computer models gives a
clear signature of greenhouse effect warming. =>Models (GCMs)
Studies find surprisingly strong "global dimming,"
due to pollution, has retarded arrival of greenhouse warming, but dimming
is now decreasing. =>Aerosols
Numerous observations raise concern that collapse of ice sheets
(West Antarctica, Greenland) can raise sea level faster than most had
believed. =>Sea rise & ice
Deadly summer heat wave in Europe accelerates divergence between European
and US public opinion. =>Public opinion
First major books, movie and art work featuring global warming appear.
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.
Hurricane Katrina and other major tropical storms spur debate over impact
of global warming on storm intensity. =>Sea rise & ice
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.
China overtakes the United States as the world’s biggest emitter of CO2.
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
Climate scientists (although not the public) recognize that even if all greenhouse gas emissions could be halted immediately, global warming will continue for millennia.=>CO2
Many experts warn that global warming is arriving at a faster
and more dangerous pace than 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
Controversial "attribution" studies find recent disastrous heat waves, droughts, extremes of precipitation, and floods were made worse by global warming. =>Impacts
An apparent pause or "hiatus" in global warming of the atmosphere since 1998 is discussed and explained; the atmosphere is still warming (the next three record-breaking years would confirm that), and the oceans have warmed up steadily. =>Modern temp's
Researchers find collapse of West Antarctic ice sheet is irreversible, will bring meters of sea level rise over future centuries. =>Sea rise & ice
Paris Agreement: nearly all nations pledge to set targets for their own greenhouse gas cuts and to report their progress.=>International
Mean global temperature is 14.8°C, the warmest
in thousands of years. Level of CO2 in the atmosphere reaches 400 ppm, the highest in millions of years.