Helmholtz-Zentrum Geesthacht, 2016-07-26

A short history of climate change

Chronological review about the most important developments connected to climate change

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 (1850-1870) is about 13.6°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

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.

Chamberlin produces a model for global carbon exchange including feedbacks.

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

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

Global warming trend since late 19th century reported.
Milankovitch proposes orbital changes as the cause of ice ages.

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

Ewing and Donn offer a feedback model for quick ice age onset.
Phillips produces a somewhat realistic computer model of the global atmosphere.
Plass calculates that adding CO2 to the atmosphere will have a significant effect on the radiation balance.

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.

Mitchell reports downturn of global temperatures since the early 1940s.
Keeling accurately measures CO2 in the Earth's atmosphere and detects an annual rise. The level is 315 ppm. Mean global temperature (five-year average) is 13.9°C.

Calculations suggest that feedback with water vapour could make the climate acutely sensitive to changes in CO2 level.

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

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.

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 would raise world temperatures a couple of degrees.

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

Astronauts walk on the Moon, and people perceive the Earth as a fragile whole.
Budyko and Sellers present models of catastrophic ice-albedo feedbacks.
Nimbus III satellite begins to provide comprehensive global atmospheric temperature measurements.

First Earth Day. Environmental movement attains strong influence, spreads concern about global degradation.
Creation of US National Oceanic and Atmospheric Administration.
Aerosols from human activity are shown to be increasing swiftly. Bryson claims they counteract global warming and may bring serious cooling.

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

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.

Oil embargo and price rise bring first "energy crisis".

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.

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.

Studies show that CFCs (1975) and also 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.

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

Second oil "energy crisis." Strengthened environmental movement encourages renewable energy sources, inhibits nuclear energy growth.
US National Academy of Sciences report finds it highly credible that doubling CO2 will bring 1.5 to 4.5°C global warming.
World Climate Research Programme launched to coordinate international research.

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

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.

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.

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

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, pointing to powerful biological and geochemical feedbacks.
Broecker speculates that a reorganization of North Atlantic Ocean circulation can bring swift and radical climate change.

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

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

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.

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

Mt. Pinatubo explodes; Hansen predicts cooling pattern, verifying (by 1995) computer models of aerosol effects.
Global warming skeptics claim that 20th-century temperature changes followed from solar influences. (The solar-climate 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.

Conference in Rio de Janeiro produces UN Framework Convention on Climate Change, but US blocks calls for serious action.
Study of ancient climates reveals climate sensitivity in same range as predicted independently by computer models.

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

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 shelves and other signs of actual current warming in polar regions.

International conference produces Kyoto Protocol, setting targets to reduce greenhouse gas emissions if enough nations sign onto a treaty.

"Super El Niño" causes weather disasters and warmest year on record (approximately matched by 2005 and 2007). Borehole data confirm extraordinary warming trend.
Qualms about arbitrariness in computer models diminish as teams model ice-age climate and dispense with special adjustments to reproduce current climate.

Criticism that satellite measurements show no warming are dismissed by National Academy Panel.
Ramanathan detects massive "brown cloud" of aerosols from South Asia.

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.

Third IPCC report states baldly that global warming, unprecedented since end of last ice age, is "very likely," with possible severe surprises. Effective end of debate among all but a few scientists.
Bonn meeting, with participation of most countries but not US, develops mechanisms for working towards Kyoto targets.
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.

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

Numerous observations raise concern that collapse of ice sheets (West Antarctica, Greenland) can raise sea levels faster than most had believed.
Deadly summer heat wave in Europe accelerates divergence between European and US public opinion.

In controversy over temperature data covering past millenium, most conclude climate variations were not comparable to the post-1980 warming.

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.

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.
Greenland and Antarctic ice sheets and Arctic Ocean sea-ice cover found to be shrinking faster than expected.

Many experts warn that global warming is arriving at a faster and more dangerous pace than anticipated just a few years earlier.
Level of CO2 in the atmosphere reaches 385 ppm.
Mean global temperature (five-year average) is 14.5°C, the warmest in hundreds, perhaps thousands of years.

From the web site “The Discovery of Global Warming” by Spencer Weart. For an overview see the book of the same title (Harvard Univ. Press, 2nd ed., 2008). Copyright © 2002-2009 Spencer Weart & American Institute of Physics. Used by permission.