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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Global cooling | 4/6 | https://en.wikipedia.org/wiki/Global_cooling | reference | science, encyclopedia | 2026-05-05T09:34:02.304703+00:00 | kb-cron |
=== 1975 National Academy of Sciences report === There also was a Report by the U.S. National Academy of Sciences (NAS) entitled, "Understanding Climate Change: A Program for Action". The report stated (p. 36) that, "The average surface air temperature in the northern hemisphere increased from the 1880s until about 1940 and has been decreasing thereafter." It also stated (p. 44) that, "If both the CO2 and particulate inputs to the atmosphere grow at equal rates in the future, the widely differing atmospheric residence times of the two pollutants means that the particulate effect will grow in importance relative to that of CO2." The report did not predict whether the 25-year cooling trend would continue. It stated (Forward, p. v) that, "we do not have a good quantitative understanding of our climate machine and what determines its course [so] it does not seem possible to predict climate", and (p. 2) "The climates of the earth have always been changing, and they will doubtless continue to do so in the future. How large these future changes will be, and where and how rapidly they will occur, we do not know." The Report's "program for action" was a call for creation of a new National Climatic Research Program. It stated (p. 62), "If we are to react rationally to the inevitable climatic changes of the future, and if we are ever to predict their future course, whether they are natural or man-induced, a far greater understanding of these changes is required than we now possess. It is, moreover, important that this knowledge be acquired as soon as possible." For that reason, it stated, "the time has now come to initiate a broad and coordinated attack on the problem of climate and climatic change."
=== 1974 Time magazine article === While these discussions were ongoing in scientific circles, other accounts appeared in the popular media. In their June 24, 1974, issue, Time presented an article titled "Another Ice Age?" that noted "the atmosphere has been growing gradually cooler for the past three decades" but noted that "Some scientists ... think that the cooling trend may be only temporary."
=== 1975 Newsweek article === An April 28, 1975, article in Newsweek magazine was titled "The Cooling World", it pointed to "ominous signs that the Earth's weather patterns have begun to change" and pointed to "a drop of half a degree [Fahrenheit] in average ground temperatures in the Northern Hemisphere between 1945 and 1968." The article stated "The evidence in support of these predictions [of global cooling] has now begun to accumulate so massively that meteorologists are hard-pressed to keep up with it." The Newsweek article did not state the cause of cooling; it stated that "what causes the onset of major and minor ice ages remains a mystery" and cited the NAS conclusion that "not only are the basic scientific questions largely unanswered, but in many cases we do not yet know enough to pose the key questions." The article mentioned the alternative solutions of "melting the Arctic ice cap by covering it with black soot or diverting Arctic rivers" but conceded these were not feasible. The Newsweek article concluded by criticizing government leaders: "But the scientists see few signs that government leaders anywhere are even prepared to take the simple measures of stockpiling food or of introducing the variables of climatic uncertainty into economic projections of future food supplies ... The longer the planners (politicians) delay, the more difficult will they find it to cope with climatic change once the results become grim reality." The article emphasized sensational and largely unsourced consequences - "resulting famines could be catastrophic", "drought and desolation", "the most devastating outbreak of tornadoes ever recorded", "droughts, floods, extended dry spells, long freezes, delayed monsoons", "impossible for starving peoples to migrate", "the present decline has taken the planet about a sixth of the way toward the Ice Age." On October 23, 2006, Newsweek issued a correction, over 31 years after the original article, stating that it had been "so spectacularly wrong about the near-term future" (though editor Jerry Adler stated that "the story wasn't 'wrong' in the journalistic sense of 'inaccurate.'")
=== Other 1970s sources === Academic analysis of the peer-reviewed studies published at that time shows that most papers examining aspects of climate during the 1970s were either neutral or showed a warming trend. In 1977, a popular book on the topic was published, called The Weather Conspiracy: The Coming of the New Ice Age.
=== 1979 WMO conference === Later in the decade, at a WMO conference in 1979, F. Kenneth Hare reported:
Fig 8 shows ... 1938 the warmest year. They [temperatures] have since fallen by about 0.4 °C. At the end there is a suggestion that the fall ceased in about 1964, and may even have reversed. Figure 9 challenges the view that the fall of temperature has ceased ... the weight of evidence clearly favours cooling to the present date ... The striking point, however, is that interannual variability of world temperatures is much larger than the trend ... it is difficult to detect a genuine trend It is questionable, moreover, whether the trend is truly global. Calculated variations in the 5-year mean air temperature over the southern hemisphere chiefly with respect to land areas show that temperatures generally rose between 1943 and 1975. Since the 1960-64 period this rise has been strong ... the scattered SH data fail to support a hypothesis of continued global cooling since 1938. [p 65]
== Late-20th-century cooling predictions ==
=== 1980s === Concerns about nuclear winter arose in the early 1980s from several reports. Similar speculations have appeared over effects due to catastrophes such as asteroid impacts and massive volcanic eruptions.