tmpSpencer R. Weart,

The Discovery of Global Warming, (Cambridge: Harvard U. Press, 2003); on - line version.

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earthWeart traces the early hypothesis and later development of Global Warming thought.

He discusses how the concept was tested by skeptical professional audiences until the scientists' warnings dovetail with public concerns and the energy crisis of the 1970s.

A thematic thread in the text is that such a widespread, strong, and persistent belief in Balance of Nature inhibited our understanding of the seriousness, depth, and duration of this existing problem.

Greenhouse effect.

History of an idea.


Frequently Asked Questions

1: How Could Climate Change?
P 1
2: Discovering a Possibility
P 20
3: A Delicate System
P 39
4: A Visible Threat
P 66
5: Public Warnings
P 90
6: The Erratic Beast
P 118
7: Breaking into Politics
P 142
8: The Discovery Confirmed
P 160


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Greenhouse | President Carter | thousand years | Bibliography | popular view | What is GW?

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How could climate possibly change, especially due to humans ?


Stephen Callendar, 1830s –1838 spoke to the Royal Meteorological Society on warming

Joseph Fourier – speculated air could heat up due to exhaust gases
John Tyndall, 1859, laboratory experiments, “As a dam built across,…so our atmosphere” (p.4)

Svante Arrhenius, 1896
feedback, only easy to understand
“only after somebody pointed it out.” (Page 5)

James Croll, English geologist, snow reflects heat – cools down the surface. 1870s

Arvid Högbom, a colleague, was measuring industrial emissions found that human generated pollution was equal = to natural emissions, 1896. (p. 6.)

“CO2 absorbs radiation only in specific bands of the spectrum.” in the lab experiment
it took only a trace of the gas to produce bands that were saturated’ – so thoroughly opaque that adding more gas could make little difference.” (p. 7.)

Arrhenius conclusion were reject on the widespread principle of “the balance of nature,” by scientists who belied clouds due to excess water vapor from warmer air would block the heat and that oceans would absorb airborne wastes (50 time more CO2 in the seas as in the air) (p.8)

“This view of nature –superhuman, benevolent, and inherently stable – lay deep in most human cultures.”

p. 8

“flawless and imperturbable harmony.”

the uniformitarian principle – in geological science, p. 9.

“It was not a pressing issue. Callendar himself thought global warming would be a good thing for humanity, helping crops to grow more abundantly.
p. 19

“So the debates continued. Some experts championed personal theories about the cause of climate change, the single dominant force. Most scientists gave short shrift to any theory whatsoever. They set aside climate change as a puzzle too difficult for anyone to solve with the tools at hand. The idea that humans were influencing global climate by emitting CO2 sat on the shelf…a theory more peculiar and unattractive than most. (p. 19)Charles David Keeling, Cal-tech graduate, Monitoring the level of CO2 in the outdoors
p. 21)

Gilbert Plass
“took to studying how CO2 in the atmosphere absorbed infrared radiation” as a sideline to his experimental work for Lockheed and Johns Hopkins.

In 1956 Plass announced that human activity would raise the average global temperature ‘at the rate of 1.1 degree C (Celsius) per century.
p. 24.)

“It happened that the movements of carbon could now be tracked with a new tool, radiocarbon—a radioactive isotope, carbon-14.” p. 25

“Such isotopes had come under intense study during the wartime work to build nuclear weapons, and the pace had not slackened in the post war years.”

“The isotope is created in the upper atmosphere, when cosmic-ray particles from outer space strike nitrogen atoms and transform them into radioactive carbon. Some of the radiocarbon would find its way into living creatures.”

“In 1955, Hans Seuss announced that he had detected that ancient carbon had been added to the modern atmosphere, presumably from the burning of fossil fuels. But he figured that the added carbon made up barely one percent of all the carbon in the atmospheres—a figure so low that he concluded that most of the carbon derived from fossil fuels was being promptly taken up by the oceans.” pp. 26-27.

“A decade would pass before he managed to get more accurate measurements, which would show a far higher fraction of fossil carbon.” p. 27.

1955, Seuss & Roger Revelle at Scripps began researching carbon uptake in the oceans
Revelle “realized that the peculiar chemistry of seawater would prevent it from retaining all of the carbon that it might take up.” p. 28.

“Whatever CO2 humanity added to the atmosphere would not be swallowed up promptly, but only over thousands of years.

in 1957 Revelle and Suess realized that “the amount of CO2 in the atmosphere would gradually rise over the next few centuries, then level off with a total increase of 40 percent or less.” p. 29

Revelle’s famous quote: “Human being are now carrying out a large scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future.” (1957 article with Seuss [in Tellus 9 (1957) pp. 18-27.] p. 30

“Geophysics is inescapably international. Ocean currents and winds flow each day between regions. p. 31

Page 37

Keeling Curve” derived from measurement on the top of Mauna Loa peak
315 ppm 1958
375 ppm 2002
60 ppm > over 44 years 1.36 ppm increase / year
19% increase in 45 years
ppm= parts per million

Keeling’s data put the capstone on the structure built by Tyndall, Arrhenius, Callendar, Plass, and Revelle and Seuss. This was not quite the discovery of global warming. It was the discovery of the possibility of global warming. “

“The odd and unlikely theory now emerged from its cocoon, taking flight as a serious topic.” P. 38

1965 August; Boulder, Colorado Conference “Causes of Climate Change” p. 39
“Is human technology a force of geophysical scope, capable of affecting the entire globe?”
p. 40

Why the change from 1940s?
1953 London “killer smog”
“the astonishing advent of nuclear energy.”

1962, Silent Spring Rachel Carson p. 41

“Feelings of dread multiplied: whether or not technology would turn deserts into gardens, it could demonstrably turn gardens into deserts!” p. 41

in 1959 the New York Times reported that sea ice in the arctic was “only half as thick as it had been in the previous century.” p. 42

Developments in the 1950s continued
1956-57 Revelle testified before congress saying “The Earth itself is a spaceship” p. 43.
1963 Conservation Foundation had Keeling and others address at a conference what to do
1965 Science Advisory Panel

Developments in the 1960s
1966 National Academy of Sciences issued a report on how humans could influence climate [see 1981 as well – or 1976-77].

“We are just now beginning to realize that the atmosphere is not a dump of unlimited capacity.” p. 44

Pollen grain analysis Swedes p. 45.

“Pollen data were invaluable for identifying strata as an aid to oil exploration, and that paid for specialists to bring the technique to a high degree of refinement.” P. 45.

“they seemed to match the 21,000 year cycle predicted by Milankovitch’s astronomical calculations of shifts in sunlight.”

Oxygen isotope analysis 018/016 Heavy oxygen and light Oxygen ratios

Harold Urey developed the technique and of it he said it was “the toughest chemical problem I ever faced.)

Cesare Emiliani worked out a 300,000 year history based on analysis of seabed floor sediments
These findings contradicted the four glacial periods traditionally established by geologists
Würm, Mindel, Riis,

Until the findings were better understood as signals of ice sheet growth and decline.

Wallace Broecker, Lamont Geological Observatory
Looked at tropical coral reefs and used radio-isotope dating 49-50

“Again Milankovitch’s orbital cycles emerged, plainer than ever.”

Questions arose over how quickly an ice age ended. 50-52
Younger Dryas period 12,000 years ago was a period of bitterly cold weather after a warm spell (named for a Swedish arctic flower) p. 52.

“About 11,000 years ago, they said, the climate had shifted from fully glacial conditions to modern warmth within as little as a thousand years.” As “opposed to the usual view of a gradual change.” p. 52.

“wavering polar fronts that dominate much of the world’s weather.”
p. 55.

1940s Early models of climate where made at U. of Chicago and Cambridge University
p. 56.

Use of computers for weather prediction due to the complexity of the numbers

Norbert Weiner & Edward Lorenz, MIT
Perturbations due to feedback throwing calculations off wildly, due to changes in initial conditions.

Lorenz realized in his computation a hidden variability.
His findings suggested there was no such thing as climate in the traditional predictive average state of weather conditions, since small perturbations could alter long term predictions.
Peter Weyl, OSU

Ice ages occur due to changes in the salinity of the oceans and shift consequently the ocean currents. p. 63-64

The threat becomes visible, 1960s & 1970s study of aerosols and smog & smoke
“In particular, the warming of the globe in the first half of the century did not match any slackening of eruptions (volcanic).”

1970 , MIT conference for a month outlined Environmental threats, Global Climate Change headed the list.

1971, Stockholm meeting of international experts 14 nations due to 1970 MIT meeting:
“Study of Man’s Impact on Climate.”

“Oh Mother Earth,…pardon me for trampling on you.”
Old Sanskrit veda (prayer) p. 71

1972 failure of the East Indian Monsoon, Russian & Sahel droughts\
UofW team discovered the great & prolonged drought of the 1200s

their studies revealed rapid changes in forest cover 10,500 years ago – revealing a dramatic and discontinuous pattern of catastrophic climate change in even 100 years

Greenland Ice core 100,000 years old Antarctic ice cores

p. 73.

showed ice ages to be global occurring N S poles simultaneously

p. 74.

100,000 year cycle was prominent

p. 75.

potassium argon dating of a million year sea floor sediment showed not 4 but dozens of ice ages p 76

1970 Mercer at OhioSU speculated on the West Antarctic Ice Sheet breaking up and causing a rise in sea level of 16 feet which could happen in as little as 40 years.

1972 scientists made public warnings of global climate change due to CO2 increases
1977 National Academy of Science report “Energy and Climate”
“warning again climate shocks might be in store.”

“Officials were starting to grasp the fact that CO2 emissions had economic implications—and therefore political ones.”
p. 96

At last in 1978 Congress passed the National Climate Act, establishing a National Climate Program Office within NOAA. p. 97

“Little was known about connections between the planet’s biomass and the atmosphere. The few people who looked into the question found that the amount of carbon in the atmosphere is only a fraction of the amount bound up in trees, peat bogs, soils and other products of terrestrial life (reefs). These ecosystems and their stock of organic carbon seemed to have been fairly stable over millions of years.”

p. 100-101

“This was one more version of the argument that the atmosphere was automatically stabilized, part of the indestructible Balance of Nature.”

“clouds could either cool a region (by reflecting sunlight) or warm it (by trapping heat radiation from below). It depended on the type of clouds and how high they floated in the atmosphere.”

p. 113

“the problem is enormously complex.”

“but the course of events was no longer natural. More and more scientists felt that the greenhouse effect was the main thing to worry about.” p. 114

Stephen Schneider modeled 1000 years of volcanic activity predicted after 1980s the CO2 would dominate surface temperatures.”

p. 114

1976, James Hansen & NAS report on GCMs (planet will be noticeably warmer

Also see Hansen,

p. 122

Ed Lorenz, “butterfly’s wings” remark and initial conditions

p. 118

Broecker – downtrend in the 80 year solar cycle could and was canceling out the greenhouse effect

1986, Tom Wigley entirely solid analysis.

p. 121.

Broeker's Warning


1975, he, Broecker published his belief that “the world may be poised on the brink of a serious rise in temperature. ‘Complacency may not be warranted….We may be in for a climate surprise.’”

p. 123

CFCs, HCFCs, and sulfates

“It turned out, as expected, that the oceans would delay the appearance of global warming for a few decades by soaking up heat.”

Hence Hansen’s group warned such a masking would make any “wait and see attitude” quite “wrongheaded, for a temperature rise in the atmosphere might not become apparent until much more greenhouse effect warming was inevitable.” p. 138

The main reservoir of carbon was the oceans.” p. 139.
Broecker consulted with oceanographers

“In fact, scientists later realized that the rapid variations seen in the ice cores were merely an artifact. They did not reflect changes in the atmospheric CO2, but only changes in the ice’s acidity due too dust layers (something had indeed changed swiftly, but not necessarily the CO2 level).” p. 139

Broecker, though based on faulty understanding, stumbled upon the “ocean conveyor belt” seawater carrying heat” poleward

1/3 of the sun’s North Atlantic energy is transported north by the gulf stream to Iceland & UK
1985 Broecker argued The conveyor belt could shut down”

an extension of TC Chamberlains conjecture of the last century of less salty North Atlantic water

“Such a shutdown had actually happened” “the younger Dryas” p. 140.
Thermohaline circulation
At 4 times the present level of CO2, models predict the circulation shuts down the Nat conveyor p. 141

“There was reason to believe a shutdown could happen swiftly.”
In 1987, Broecker to the news public, “now we must view it [the greenhouse effect] as a threat to human beings and wildlife.” p. 141

“The climate system was a capricious beast, he said, and we were poking it with a sharp stick.” p. 141
Global warming had emerged from being “a cocktail hour curiosity” to a life threatening agent of change.

Roger Revelle’s Harvard Lectures, 1966 and Al Gore (student) later Congressman in Reagan years of budget cuts to weather bureau and research agencies

In 1981, for example, Hansen sent Sullivan a scientific report he was about to publish, the one announcing that the planet was getting noticeably warmer. For the first time the greenhouse effect made page one of the New York Times.”

unprecedented warning “a disastrous rise in sea level.” p. 144
NY Times editorialized that GW was “no longer unimaginable”
DofEnergy responded by cutting Hansen’s budget to the tune of his laying off five researchers. p. 144

Everything connected with atmospheric change had become politically sensitive.”

due to acid rain controversy and the power of coal companies to thwart changes
October 18 1983 another New York Time’s front page story of EPA dire warning that GW was a threat that could be felt in a few years. Countered a less worrisome NAS report which said the change would be well within a range humans could adjust to. p. 146

“It was official, global warming might well be coming.”
Ocean Thermal Expansion p. 147

Small mountain glaciers were shrinking
…so the proper response was to study it! 148
as studies accumulated so did negative findings, loss of coral reefs, tropical diseases spreading p. 149

1985 Villach, Austria Meteorological meeting & announcement:

“in the first half of the next century a rise of global mean temperature could occur which is greater than any in man’s history.” p. 151

by late 1980s experts had become “frantic” to inform the public and skeptics alike 151

1987, “epochal” Montreal Protocol p. 153

1979 European wide action to curtail acid rain, due to scientific evidence.

1988, Toronto Conference, scientists first asked government to set targets, limits on the amount of GHG emissions due to global threat of warming. Asked that by 2005, emission be placed 20% below 1988 levels. P. 154.

Despite 1980s as the hottest years on record, little journalistic attention was paid to GW
“To ignite worries, only a match was needed.” Pp. 154-55.

Summer 1988, droughts on the great plains were worst since Dust Bowl, was the ignition

p. 155

Hansen and Senator Timothy Wirth testified at Congressional hearings:

“the long term warming trend was underway.”

“The greenhouse effect is here.”

Hansen p. 155.

So who is unaware that it is here?

  1. Its not here
  2. It is a cycle, and not global warming
  3. If it is here you can't do anything about it
  4. If its here its not that serious compared to say immediate problems
  5. If its here its so big a problem we could not possibly influence the outcome
  6. none of the above



Writers and readers find it hard to pick out which recent developments will really matter in the long run....only a preliminary sketch."


"well informed people understood that the climate change issue could not be handled in either of the two easiest ways."

"for the scientists were not limited by sort of simple ignorance that could be overcome with clever studies.

That hardly seemed a convincing way to tell the civilized world how it should reorganize the way everyone lived."


formation of the IPCC under Bert Bolin's direction

Climate treaty

Kyoto Protocol


Its real, its intensifying, and our rate of greenhouse gas emissions is doubling.