View source for Global cooling

{{short description|Discredited 1970s hypothesis of imminent cooling of the Earth}}
{{Use mdy dates|date=May 2022}}
{{other uses}}
[[File:Global Cooling Map.png|thumb|right|Mean temperature anomalies during the period 1965 to 1975 with respect to the average temperatures from 1937 to 1946. This dataset was not available at the time.]]
[[File:PeerReviewedPapersComparingGlobalWarmingAndCoolingIn1970s.jpg|thumb]]
'''Global cooling''' was a conjecture, especially during the 1970s, of imminent cooling of the [[Earth]] culminating in a period of extensive [[glaciation]], due to the cooling effects of [[aerosols]] or [[orbital forcing]]. 
Some [[newspaper|press reports]] in the 1970s speculated about continued cooling; these did not accurately reflect the scientific literature of the time, which was generally more concerned with warming from an enhanced [[greenhouse effect]].<ref name="The Myth of the 1970s Global Cooling Scientific Consensus" />

In the mid 1970s, the limited temperature series available suggested that the temperature had decreased for several decades up to then. As longer time series of higher quality became available, it became clear that global temperature showed significant increases overall.{{Citation needed|date=January 2025}}

{{anchor|Introduction}}

== Introduction: general awareness and concern ==

By the 1970s, scientists were becoming increasingly aware that estimates of global temperatures showed cooling since 1945, as well as the possibility of large scale warming due to emissions of greenhouse gases. In the scientific papers which considered climate trends of the 21st century, fewer than 10% were inclined towards future cooling, while most papers predicted future warming.<ref name="The Myth of the 1970s Global Cooling Scientific Consensus" /> The general public had little awareness of carbon dioxide's effects on climate, but ''[[Science News]]'' in May 1959 forecast a 25% increase in atmospheric carbon dioxide in the 150 years from 1850 to 2000, with a consequent warming trend.<ref>{{cite news|url=https://www.sciencenews.org/article/science-past-issue-may-9-1959|title=Science Past from the issue of May 9, 1959|date=April 23, 2009|newspaper=Science News|page=30|url-access=subscription}}</ref> The actual increase in this period was 29%. [[Paul R. Ehrlich]] mentioned [[global warming]] from [[greenhouse gases]] as a counterforce to the [[Particulates#Climate effects|cooling effect of aerosols]] in 1968.<ref name="erhlich_1968">pages 51–52 of The Population Bomb, 1968, available from {{cite web|url=https://backseatdriving.blogspot.com/2005_07_01_backseatdriving_archive.html#112148592454360291|title=Paul Erhlich on climate change in 1968|last=Schmidt|first=Brian|date=July 1, 2005|work=Backseat driving|access-date=November 17, 2005}}</ref> By the time the idea of global cooling reached the public press in the mid-1970s temperatures had stopped falling, and there was concern in the climatological community about [[carbon dioxide]]'s warming effects.<ref>{{cite journal|last=Schneider|first=Stephen H.|date=November 1972|title=Atmospheric Particles and Climate: can we Evaluate the Impact of man's Activities?|journal=Quaternary Research|volume=2|issue=3|pages=425–35|bibcode=1972QuRes...2..425S|doi=10.1016/0033-5894(72)90068-3|s2cid=128552998 }}</ref> In response to such reports, the [[World Meteorological Organization]] issued a warning in June 1976 that "a very significant warming of global climate" was probable.<ref>"World's temperature likely to rise", ''[[The Times]]'', June 22, 1976; pg 9; col A.</ref>

Currently, there are some concerns about the possible regional cooling effects of a slowdown or [[shutdown of thermohaline circulation]], which might be provoked by an increase of [[fresh water]] mixing into the North [[Atlantic]] due to [[glacier|glacial melting]]. The [[probability]] of this occurring is generally considered to be very low, and the [[Intergovernmental Panel on Climate Change|IPCC]] notes, "even in models where the [[Thermohaline circulation|THC]] weakens, there is still warming over Europe. For example, in all [[Global climate model|AOGCM]] integrations where the [[radiative forcing]] is increasing, the sign of the [[temperature]] change over north-west Europe is positive."<ref name="IPCC sci basis">{{cite web|url=http://www.grida.no/climate/ipcc_tar/wg1/357.htm|title=Climate Change 2001: The Scientific Basis|author=Intergovernmental Panel on Climate Change|archive-url=https://web.archive.org/web/20160305033059/http://www.grida.no/climate/ipcc_tar/wg1/357.htm|archive-date=March 5, 2016|access-date=November 17, 2005}}</ref>

==Physical mechanisms==

The cooling period is reproduced by current (1999 on) [[global climate model]]s that include the physical effects of [[sulfate aerosols]], and there is now general agreement that [[aerosol]] effects were the dominant cause of the mid-20th century cooling. At the time there were two physical mechanisms that were most frequently advanced to cause cooling: aerosols and orbital forcing.

===Aerosols===
{{Main|Particulates#Climate effects}}
Human activity &mdash; mostly as a by-product of [[fossil fuel]] [[combustion]], partly by [[land use]] changes &mdash; increases the number of tiny particles ([[aerosol]]s) in the atmosphere. These have a direct effect: they effectively increase the planetary [[albedo]], thus cooling the [[planet]] by reducing the [[solar radiation]] reaching the surface; and an indirect effect: they affect the properties of clouds by acting as [[cloud condensation nuclei]].<ref>{{cite journal|last1=Rasool|first1=S.I.|last2=Schneider|first2=S.H.|title=Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate|journal=Science|date=July 9, 1971|volume=173|issue=3992|pages=138–41|bibcode=1971Sci...173..138R|doi=10.1126/science.173.3992.138|pmid=17739641|s2cid=43228353}}</ref> In the early 1970s some speculated that this cooling effect might dominate over the warming effect of the [[carbon dioxide|CO<sub>2</sub>]] release: see discussion of Rasool and Schneider (1971), below. As a result of observations and a switch to cleaner fuel burning, this no longer seems likely; current scientific work indicates that [[global warming]] is far more likely. Although the temperature drops foreseen by this mechanism have now been discarded in light of better theory and the observed warming, aerosols are thought to have contributed a cooling tendency (outweighed by increases in greenhouse gases) and also have contributed to [[global dimming]].

===Orbital forcing===
{{Main|Orbital forcing}}
[[File:Vostok Petit data.svg|thumb|upright=1.15|right|CO<sub>2</sub>, temperature, and dust concentration measured by Petit et al. from Vostok ice core at Antarctica.]]
Orbital forcing refers to the [[Milankovitch cycles|slow, cyclical changes]] in the tilt of Earth's [[Axis of rotation|axis]] and shape of its [[orbit]]. These cycles alter the total amount of sunlight reaching the Earth by a small amount and affect the timing and intensity of the [[seasons]]. This mechanism is thought to be responsible for the timing of the [[ice age]] [[Climate change (general concept)|cycles]], and understanding of the mechanism was increasing rapidly in the mid-1970s.

The paper of Hays, Imbrie, and Shackleton "Variations in the Earth's Orbit: Pacemaker of the Ice Ages" qualified its predictions with the remark that "forecasts must be qualified in two ways. First, they apply only to the natural component of future climatic trends - and not to [[Human impact on the environment|anthropogenic effects]] such as those due to the burning of [[fossil fuels]]. Second, they describe only the long-term trends, because they are linked to orbital variations with [[Orbital period|period]]s of 20,000 years and longer. Climatic [[oscillations]] at higher frequencies are not predicted&nbsp;... the results indicate that the long-term trend over the next 20,000 years is towards extensive Northern Hemisphere glaciation and cooler climate".<ref>{{cite journal|last1=Hays|first1=J.D.|last2=Imbrie|first2=John|last3=Shackleton|first3=N.J.|title=Variations in the Earth's Orbit: Pacemaker of the Ice Ages|journal=Science|date=December 10, 1976|volume=194|issue=4270|pages=1121–32|bibcode=1976Sci...194.1121H|doi=10.1126/science.194.4270.1121|pmid=17790893|s2cid=667291}}</ref>

The idea that ice age cycles were predictable appears to have become conflated with the idea that another one was due "soon" - perhaps because much of this study was done by geologists, who are accustomed to dealing with very long time scales and use "soon" to refer to periods of thousands of years. A strict application of the [[Milutin Milanković|Milankovitch]] theory does not allow the prediction of a "rapid" ice age onset (i.e., less than a century or two) since the fastest orbital period is about 20,000 years.{{cn|date=December 2022}} Some creative ways around this were found, notably one championed by [[Nigel Calder]] under the name of "snowblitz", but these ideas did not gain wide acceptance.

The length of the current [[interglacial]] temperature peak is similar to the length of the preceding interglacial peak (Sangamon/Eem), and so it could be concluded that we might be nearing the end of this warm period. This conclusion would be mistaken. Firstly, because the lengths of previous interglacials were not particularly regular;<ref>{{Cite journal |last1=Tzedakis |first1=P. C. |last2=Wolff |first2=E. W. |last3=Skinner |first3=L. C. |last4=Brovkin |first4=V. |last5=Hodell |first5=D. A. |last6=McManus |first6=J. F. |last7=Raynaud |first7=D. |date=2012-09-24 |title=Can we predict the duration of an interglacial? |url=https://cp.copernicus.org/articles/8/1473/2012/ |journal=Climate of the Past |language=en |volume=8 |issue=5 |pages=1473–1485 |doi=10.5194/cp-8-1473-2012 |bibcode=2012CliPa...8.1473T |issn=1814-9332|doi-access=free |hdl=11858/00-001M-0000-000F-E785-C |hdl-access=free }}</ref> see figure. Petit et al. note that "interglacials 5.5 and 9.3 are different from the [[Holocene]], but similar to each other in duration, shape and amplitude. During each of these two events, there is a warm period of 4 kyr followed by a relatively rapid cooling".<ref>{{Cite journal|last=Petit|first=Jean-Robert|display-authors=et al.|title=Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica|url=http://www.escholarship.org/uc/item/7rx4413n|journal=Nature|date=June 3, 1999|volume=399|issue=6735|pages=429–36|doi=10.1038/20859|bibcode=1999Natur.399..429P|s2cid=204993577}}</ref> Secondly, future orbital variations will not closely resemble those of the past.

==Concern pre-1970s==
In 1923, there was concern about a new ice age and Captain [[Donald Baxter MacMillan]] sailed toward the [[Arctic]] sponsored by the [[National Geographical Society]] to look for evidence of advancing glaciers.<ref>{{cite news |url=https://www.nytimes.com/1923/07/04/archives/macmillan-sails-north-explorer-hopes-to-determine-whether-new-ice.html|title=MacMillan Sails North. Explorer Hopes to Determine Whether New 'Ice Age' Is Coming|date=July 4, 1923 |newspaper=[[The New York Times]]|access-date=March 11, 2015|quote=Captain Donald B. MacMillan, Arctic explorer, and his picked crew of six sailed for the Far North tonight}}</ref><ref>{{cite news |url=https://www.nytimes.com/1923/05/28/archives/macmillan-to-seek-signs-of-new-ice-age-his-expedition-equipped-for.html|title=MacMillan to Seek Signs of New Ice Age. His Expedition Equipped for Polar Radio|date=May 28, 1923 |newspaper=The New York Times|access-date=March 11, 2015|quote=Captain Donald B. MacMillan, who will sail from here June 16 on the little schooner Bowdoin to resume his arctic explorations, announced today that one purpose of the expedition is to determine whether there is beginning another ice age, as the advance of glaciers in the last seventy years would indicate.}}</ref>

In 1926, a Berlin astronomer was predicting global cooling but that it was "ages away".<ref>{{cite news|url=https://www.nytimes.com/1926/02/14/archives/bogy-of-a-new-ice-age-berlin-astronomer-discusses-its-possibilities.html |title=A New Ice Age. Berlin Astronomer Discusses Its Possibilities and Chills German Hearts. Glacier Onslaught Is Apparently Ages Away|date=February 14, 1926|newspaper=The New York Times|access-date=March 11, 2015|quote=There can be no doubt that the weather of our planets has been abnormal of recent years. Whether this be due directly to the health, disposition or constitution of our globe itself, or to the weather from without, as the new glacial cosmogony would teach us, must remain a question for experts to debate, if not settle.}}</ref>

Concerns that a new ice age was approaching was revived in the 1950s.<ref>{{cite news |url=https://www.nytimes.com/1956/11/11/archives/get-out-the-ear-muffs-new-ice-age-forecast.html |title=Get Out the Ear Muffs. New Ice Age Forecast|date=November 11, 1956|newspaper=The New York Times|access-date=March 11, 2015|quote=New findings of 'atomic timekeeping' suggest that North America may be heading into another major Ice Age, a Government geologist said today.}}</ref> During the [[Cold War]], there were concerns by [[Harry Wexler]] that setting off [[atom bombs]] could be hastening a new ice age from a [[nuclear winter]] scenario.<ref>{{cite news |url=https://www.nytimes.com/1958/11/02/archives/hbombs-visioned-as-thawing-pole-but-scientist-warns-that-arctic.html|title=Scientist Warns That Arctic Blast Could Lead to a New Ice Age|last=Sullivan|first=Walter|date=November 2, 1958|newspaper=The New York Times|access-date=March 11, 2015|quote=A few well-placed hydrogen bombs might set in motion a sequence of events that would clear the Arctic Ocean of ice, but the result could be the start of a new ice age.&nbsp;... This hypothesis was reported by Dr. Harry Wexler, Director of Meteorological}}</ref>

[[J. Murray Mitchell]] showed as early as 1963 a multidecadal cooling since about 1940.<ref name="The Myth of the 1970s Global Cooling Scientific Consensus">{{cite journal|last1=Peterson|first1=Thomas |last2=Connolley |first2=William|last3=Fleck|first3=John|date=September 2008|title=The Myth of the 1970s Global Cooling Scientific Consensus|journal=Bulletin of the American Meteorological Society|volume=89 |issue=9|pages=1325–1337 |bibcode=2008BAMS...89.1325P |doi=10.1175/2008BAMS2370.1 |s2cid=123635044 |url=http://nora.nerc.ac.uk/id/eprint/11584/1/2008bams2370%252E1.pdf}}</ref> At a conference on climate change held in [[Boulder, Colorado]] in 1965, evidence supporting [[Milankovitch cycles]] triggered speculation on how the calculated small changes in sunlight might somehow trigger ice ages. In 1966, [[Cesare Emiliani]] predicted that "a new glaciation will begin within a few thousand years." In his 1968 book ''[[The Population Bomb]]'', [[Paul R. Ehrlich]] wrote "The [[greenhouse effect]] is being enhanced now by the greatly increased level of [[carbon dioxide]]&nbsp;... [this] is being countered by low-level clouds generated by contrails, dust, and other contaminants&nbsp;... At the moment we cannot predict what the overall climatic results will be of our using the [[atmosphere]] as a garbage dump."<ref name="erhlich_1968"/>

==Concern in the 1970s==

===1970s awareness===
{{Multiple image|direction=vertical|align=right|image1=Global cooling.jpg|image2=Global Temperature Anomaly.svg|width=250|caption1=The temperature record as seen in 1975; compare with the next figure.|caption2=Global mean surface temperature change since 1880. Source: [http://data.giss.nasa.gov/gistemp/ NASA GISS]}}
Concern peaked in the early 1970s, though "the possibility of anthropogenic warming dominated the peer-reviewed literature even then" <ref name="The Myth of the 1970s Global Cooling Scientific Consensus"/> (a cooling period began in 1945, and two decades of a cooling trend suggested a trough had been reached after several decades of warming). This peaking concern is partially attributable to the fact much less was then known about world climate and [[Ice age#Causes of ice ages|causes of ice ages]]. Climate scientists were aware that predictions based on this trend were not possible - because the trend was poorly studied and not understood (for example see reference<ref>{{cite web | title= QJRMS, 1976, p 473 (Symons Memorial Lecture) | work=Was an imminent Ice Age predicted in the '70s? No |author= Mason, B. J. | url=http://www.wmconnolley.org.uk/sci/iceage/mason.1976.html | access-date=November 17, 2005}}</ref>). Despite that, in the popular press the possibility of cooling was reported generally without the caveats present in the scientific reports, and "unusually severe winters in Asia and parts of North America in 1972 and 1973&nbsp;... pushed the issue into the public consciousness".<ref name="The Myth of the 1970s Global Cooling Scientific Consensus"/>

In the 1970s, the compilation of records to produce hemispheric, or global, temperature records had just begun.

[[Spencer R. Weart]]'s history of ''[[The Discovery of Global Warming]]'' says that: "While neither scientists nor the public could be sure in the 1970s whether the world was warming or cooling, ''people were increasingly inclined to believe that global climate was on the move, and in no small way''" [emphasis added].<ref>{{cite web | title=The Modern Temperature Trend | work=The Discovery of Global Warming | author=Weart, Spencer | url=http://www.aip.org/history/climate/20ctrend.htm#L_0338 | access-date=November 17, 2005 | archive-date=September 22, 2020 | archive-url=https://web.archive.org/web/20200922100047/http://www.aip.org/history/climate/20ctrend.htm#L_0338 | url-status=dead }}</ref>

On January 11, 1970, ''[[The Washington Post]]'' reported that "Colder Winters Held Dawn of New Ice Age".<ref>{{cite news|url=https://www.proquest.com/docview/147902052|title=Colder Winters Held Dawn of New Ice Age|date=January 11, 1970|newspaper=[[The Washington Post]]|access-date=March 11, 2015|quote=Get a good grip on your long johns, cold weather haters -- the worst may be yet to come. That's the long-long-range weather forecast being given out by 'climatologists.' the people who study very long-term world weather trends.|archive-url=https://web.archive.org/web/20150221224323/http://pqasb.pqarchiver.com/washingtonpost_historical/doc/147902052.html?FMT=ABS&FMTS=&type=historic&date=washingtonpost+%2C+&author=Washington+Post+Staff+Writer%3B+By+David+R.+Boldt&pub=The+Washington+Post%2C+Times+Herald+%281959-1973%29&desc=Colder+Winters+Held+Dawn+of+New+Ice+Age&pqatl=top_retrieves|archive-date=February 21, 2015|id={{ProQuest|147902052}} |url-status=live}}</ref>

In 1972, Emiliani warned "Man's activity may either precipitate this new ice age or lead to substantial or even total melting of the ice caps".<ref>{{cite journal |first1=Cesare |last1=Emiliani |title=Quaternary hypsithermals |journal=Quaternary Research |volume=2 |issue=3 |date=November 1972 |pages=270–3 |doi=10.1016/0033-5894(72)90047-6|bibcode = 1972QuRes...2..270E|s2cid=127414000 }}</ref>

Also in 1972, a group of glacial-epoch experts at a conference agreed that "the natural end of our warm epoch is undoubtedly near";<ref>{{Cite web|url=https://history.aip.org/climate/cycles.htm|title=Past Climate Cycles: Ice Age Speculations|website=history.aip.org}}</ref> but the volume of Quaternary Research reporting on the meeting said that "the basic conclusion to be drawn from the discussions in this section is that the knowledge necessary for understanding the mechanism of climate change is still lamentably inadequate". [[George Kukla]] and Robert Matthews, in a ''[[Science (journal)|Science]]'' write-up of a conference, asked when and how the current interglacial would end; concluding that, unless there were impacts from future human activity, "Global cooling and related rapid changes of environment, substantially exceeding the fluctuations experienced by man in historical times, must be expected within the next few millennia or even centuries",<ref name="Kukla 1972">{{cite journal |title=When Will the Present Interglacial End? |first1=G. J. |last1=Kukla |first2=R. K. |last2=Matthews |journal=Science |year=1972 |volume=178 |issue=4057 |pages=190–202 |doi=10.1126/science.178.4057.190 |pmid=17789488 |bibcode = 1972Sci...178..190K}}</ref> but many other scientists doubted these conclusions.<ref>{{cite web | title=Past Cycles: Ice Age Speculations | work=The Discovery of Global Warming | author=Weart, Spencer | url=http://www.aip.org/history/climate/cycles.htm | access-date=November 17, 2005 | archive-date=January 11, 2016 | archive-url=https://web.archive.org/web/20160111060106/http://www.aip.org/history/climate/cycles.htm | url-status=dead }}</ref>

=== 1970 SCEP report ===

The 1970 [[Study of Critical Environmental Problems]]<ref>{{cite book|url=https://archive.org/details/mansimpactonglob0000stud|title=Man's Impact On The Global Environment: Assessment and Recommendations for Action|author1=Study of Critical Environmental Problems (SCEP)|date=October 1970|publisher=MIT Press|isbn=9780262690270|pages=[https://archive.org/details/mansimpactonglob0000stud/page/319 319]|access-date=February 3, 2016|url-access=registration}}</ref> reported the possibility of warming from increased carbon dioxide, but no concerns about cooling, setting a lower bound on the beginning of interest in "global cooling".

===1971 to 1975: papers on warming and cooling factors===
By 1971, studies indicated that human caused air [[pollution]] was spreading, but there was uncertainty as to whether aerosols would cause warming or cooling, and whether or not they were more significant than rising {{co2}} levels. [[J. Murray Mitchell]] still viewed humans as "innocent bystanders" in the cooling from the 1940s to 1970, but in 1971 his calculations suggested that rising emissions could cause significant cooling after 2000, though he also argued that emissions could cause warming depending on circumstances. Calculations were too basic at this time to be trusted to give reliable results.<ref>{{Cite web |last=Weart |first=Spencer |title=Aerosols: Volcanoes, Dust, Clouds and Climate – Warming or Cooling? (Early 1970s) |url=http://www.aip.org/history/climate/aerosol.htm#s2 |publisher=American Institute of Physics |date=2003–2011 |access-date=February 6, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20160629153004/https://www.aip.org/history/climate/aerosol.htm#s2 |archive-date=June 29, 2016}}</ref><ref>{{cite journal |last=Mitchell |first=J. Murray Jr. |date=1971 |title=The Effect of Atmospheric Aerosols on Climate with Special Reference to Temperature near the Earth's Surface |url=http://ruby.fgcu.edu/courses/twimberley/EnviroPhilo/Aerosols.pdf |url-status=live |archive-url=https://web.archive.org/web/20160303235932/http://ruby.fgcu.edu/courses/twimberley/EnviroPhilo/Aerosols.pdf |archive-date=2016-03-03 |journal=Journal of Applied Meteorology |volume=10 |issue=4 |pages=703–714|doi=10.1175/1520-0450(1971)010<0703:TEOAAO>2.0.CO;2 |bibcode=1971JApMe..10..703M }}</ref>

An early numerical computation of climate effects was published in the journal ''Science'' in July 1971 as a paper by [[S. Ichtiaque Rasool]] and [[Stephen Schneider (scientist)|Stephen H. Schneider]], titled "Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate".<ref>{{cite news |last=Cohn |first=Victor |date=July 9, 1971 |title=U.S. Scientist Sees New Ice Age Coming |newspaper=The Washington Post |url=https://www.proquest.com/docview/148085303 |access-date=March 11, 2015 |quote=The world could be as little as 50 or 60 years away from a disastrous new ice age, a leading atmospheric scientist predicts. Dr. S. I. Rasool of the National Aeronautics and Space Administration and Columbia University says |archive-date=February 21, 2015 |archive-url=https://web.archive.org/web/20150221225924/http://pqasb.pqarchiver.com/washingtonpost_historical/doc/148085303.html?FMT=ABS&FMTS=&type=historic&date=washingtonpost+%2C+&author=By+Victor+Cohn%3B+Washington+Post+Staff+Writer&pub=The+Washington+Post%2C+Times+Herald+%281959-1973%29&desc=U.S.+Scientist+Sees+New+Ice+Age+Coming&pqatl=top_retrieves |id={{ProQuest|148085303}} |url-status=live }}</ref>
The paper used rudimentary data and equations to compute the possible future effects of large increases in the densities in the atmosphere of two types of human environmental emissions:<ref name="Weart aerosols">{{Cite web |last=Weart |first=Spencer |date=2003–2011 |title=Aerosols: Volcanoes, Dust, Clouds and Climate |url=http://www.aip.org/history/climate/aerosol.htm#L_0338 |publisher=American Institute of Physics |access-date=February 6, 2012 |url-status=dead |archive-date=June 29, 2016 |archive-url=https://web.archive.org/web/20160629153004/https://www.aip.org/history/climate/aerosol.htm#L_0338}}</ref>
# greenhouse gases such as carbon dioxide;
# particulate pollution such as smog, some of which remains suspended in the atmosphere in aerosol form for years.
The paper suggested that the global warming due to greenhouse gases would tend to have less effect with greater densities, and while aerosol pollution could cause warming, it was likely that it would tend to have a cooling effect which increased with density. They concluded that "An increase by only a factor of 4 in global aerosol background concentration may be sufficient to reduce the surface temperature by as much as 3.5 ° K. If sustained over a period of several years, such a temperature decrease over the whole globe is believed to be sufficient to trigger an ice age."<ref>{{Cite journal | last1 = Rasool | first1 = S. I. | last2 = Schneider | first2 = S. H. | doi = 10.1126/science.173.3992.138 | title = Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate | journal = Science | volume = 173 | issue = 3992 | pages = 138–141 | year = 1971 | pmid = 17739641|bibcode = 1971Sci...173..138R | s2cid = 43228353}}</ref>

Both their equations and their data were badly flawed, as was soon pointed out by other scientists and confirmed by Schneider himself.<ref name="Weart aerosols"/> In January 1972, [[Robert Jay Charlson]] et al. pointed out that with other reasonable assumptions, the model produced the opposite conclusion.<ref>{{Cite journal|last1=Charlson|first1=R. J.|last2=Harrison|first2=H.|last3=Witt|first3=G.|last4=Rasool|first4=S. I.|last5=Schneider|first5=S. H.|title=Aerosol Concentrations: Effect on Planetary Temperatures|journal=Science|date=January 7, 1972|volume=175|issue=4017|pages=95–6|bibcode=1972Sci...175...95C|doi=10.1126/science.175.4017.95-a|pmid=17833984|doi-access=}}</ref> The model made no allowance for changes in clouds or convection, and erroneously indicated that eight times as much {{co2}} would only cause 2&nbsp;°C of warming.<ref>{{Cite web | last = Weart | first = Spencer | title = Aerosols: Volcanoes, Dust, Clouds and Climate: footnote 31 | url = http://www.aip.org/history/climate/aerosol.htm#N_31_ | publisher = American Institute of Physics | date = 2003–2011 | access-date = February 6, 2012 | archive-url = https://web.archive.org/web/20160629153004/https://www.aip.org/history/climate/aerosol.htm#N_31_ | archive-date = June 29, 2016 | url-status = dead}}</ref> In a paper published in 1975, Schneider corrected the overestimate of aerosol cooling by checking data on the effects of dust produced by volcanoes. When the model included estimated changes in solar intensity, it gave a reasonable match to temperatures over the previous thousand years and its prediction was that "{{CO2}} warming dominates the surface temperature patterns soon after 1980."<ref>{{Cite web | last = Weart | first = Spencer | title = Aerosols: Volcanoes, Dust, Clouds and Climate: Schneider part b | url = http://www.aip.org/history/climate/aerosol.htm#b_Schneider | publisher = American Institute of Physics | date = 2003–2011 | access-date = February 6, 2012 | archive-url = https://web.archive.org/web/20160629153004/https://www.aip.org/history/climate/aerosol.htm#b_Schneider | archive-date = June 29, 2016 | url-status = dead}}</ref>

===1972 and 1974 National Science Board===
The [[National Science Board]]'s ''Patterns and Perspectives in Environmental Science'' report of 1972 discussed the cyclical behavior of climate, and the understanding at the time that the planet was entering a phase of cooling after a warm period. "Judging from the record of the past interglacial ages, the present time of high temperatures should be drawing to an end, to be followed by a long period of considerably colder temperatures leading into the next glacial age some 20,000 years from now."<ref name="NSB72-p55">{{cite book
 | title = Patterns and Perspectives in Environmental Science (Hardcover)
 | series = Report of the National Science Board
 | publisher = [[United States Government Publishing Office|Government Printing Office]]
 | year = 1972
 | url = https://archive.org/details/patternsperspect00nati
 | access-date = July 15, 2008
 | pages = [https://archive.org/details/patternsperspect00nati/page/55 55]}}
</ref> But it also continued; "However, it is possible, or even likely, that human interference has already altered the environment so much that the climatic pattern of the near future will follow a different path."<ref name="NSB72-p55" />

The board's report of 1974, ''Science And The Challenges Ahead'', continued on this theme. "During the last 20-30 years, world temperature has fallen, irregularly at first but more sharply over the last decade."<ref name="NSB74-p24">{{cite book
 | title = Science and the challenges ahead : report of the National Science Board
 | publisher = [[United States Government Publishing Office|Government Printing Office]]
 | year = 1974
 | url = https://archive.org/details/sciencechallenge00nati
 | access-date = July 18, 2008
 | pages = [https://archive.org/details/sciencechallenge00nati/page/24 24]}}
</ref> Discussion of cyclic [[glacial period]]s does not feature in this report. Instead it is the role of humans that is central to the report's analysis.
"The cause of the cooling trend is not known with certainty. But there is increasing concern that man himself may be implicated, not only in the recent cooling trend but also in the warming temperatures over the last century".<ref name="NSB74-p24" /> The report did not conclude whether carbon dioxide in warming, or agricultural and industrial pollution in cooling, are factors in the recent climatic changes, noting;
"Before such questions as these can be resolved, major advances must be made in understanding the chemistry and physics of the atmosphere and [[oceans]], and in measuring and tracing [[Atmospheric particulate matter|particulates]] through the system."<ref name="NSB74-p25">{{cite book
 | title = Science and the challenges ahead : report of the National Science Board
 | publisher = [[United States Government Publishing Office|Government Printing Office]]
 | year = 1974
 | url = https://archive.org/details/sciencechallenge00nati
 | access-date = July 18, 2008
 | pages = [https://archive.org/details/sciencechallenge00nati/page/25 25]}}
</ref>

===1975 National Academy of Sciences report===
There also was a Report by the U.S. [[United States National Academy of Sciences|National Academy of Sciences]] (NAS) entitled, "Understanding Climate Change: A Program for Action".<ref>{{cite book|url=https://archive.org/details/understandingcli00unit|title=Understanding Climate Change: A Program for Action|author=U. S. National Academy of Sciences|year=1975|via=Internet Archive|access-date=January 6, 2014|publisher=Washington : National Academy of Sciences}}</ref>

The report stated (p.&nbsp;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.&nbsp;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.&nbsp;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.&nbsp;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 (magazine)|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&nbsp;... think that the cooling trend may be only temporary."<ref>{{cite magazine| url=http://www.time.com/time/magazine/article/0,9171,944914,00.html | archive-url=https://web.archive.org/web/20061108113528/http://www.time.com/time/magazine/article/0,9171,944914,00.html | url-status=dead | archive-date=November 8, 2006 | magazine=[[Time (magazine)|Time]]| title=Science: Another Ice Age? | date=June 24, 1974}}</ref>

===1975 ''Newsweek'' article===
An April 28, 1975, article in ''[[Newsweek]]'' magazine was titled "The Cooling World",<ref name="newsweek-1975">{{cite news|url=https://html1-f.scribdassets.com/yal7w1ekg3t0s2a/images/1-9c290725b9.jpg|title=The Cooling World|last=Gwynne|first=Peter|date=April 28, 1975|newspaper=[[Newsweek]]|archive-url=https://web.archive.org/web/20180625112826/https://html1-f.scribdassets.com/yal7w1ekg3t0s2a/images/1-9c290725b9.jpg|archive-date=June 25, 2018|url-status=dead|via=Scribd|access-date=July 1, 2018}}</ref> 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&nbsp;... 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."<ref name="newsweek-1975"/><ref>{{cite news|url=http://www.newsweek.com/newsweek-rewind-debunking-global-cooling-252326|title=Newsweek Rewind: Debunking Global Cooling|last=Verger|first=Rob|date=May 23, 2014|newspaper=[[Newsweek]]|access-date=January 25, 2015}}</ref>

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.{{'"}})<ref>{{cite news|url=http://www.newsweek.com/id/72481|title=Remember Global Cooling?|last=Adler|first=Jerry|date=October 22, 2006|newspaper=Newsweek}}</ref>

===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.<ref name="The Myth of the 1970s Global Cooling Scientific Consensus"/>

In 1977, a popular book on the topic was published, called ''The Weather Conspiracy: The Coming of the New Ice Age''.<ref>{{cite journal
 | first=Stephen
 | last=Schneider
 | author-link=Stephen Schneider (scientist)
 | date=December 29, 1977
 | title=Against instant books
 | journal=Nature
 | volume=270
 | issue=22
 | pages=650
 | url=http://stephenschneider.stanford.edu/Publications/PDF_Papers/Schneider1977.pdf
 | doi=10.1038/270650a0
 | bibcode = 1977Natur.270..650S | s2cid=4193442
 | doi-access=free
}}</ref>

===1979 WMO conference===

Later in the decade, at a [[WMO]] conference in 1979, [[Kenneth Hare|F. Kenneth Hare]] reported:
{{quotation|
:Fig 8 shows&nbsp;... 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&nbsp;... the weight of evidence clearly favours cooling to the present date&nbsp;... The striking point, however, is that interannual variability of world temperatures is much larger than the trend&nbsp;... 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&nbsp;... the scattered SH data fail to support a hypothesis of continued global cooling since 1938. [p 65]<ref name="wcc-1979.html">{{cite web | title=World Climate Conference 1979 | work=Was an imminent Ice Age predicted in the '70s? No | url=http://www.wmconnolley.org.uk/sci/iceage/wcc-1979.html | access-date=November 17, 2005}}</ref>
}}

==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 [[Impact event|asteroid impacts]] and massive [[Yellowstone Caldera|volcanic eruptions]].

===1990s===
In 1991, a prediction by [[Carl Sagan]] and other scientists who had worked on the famous [[TTAPS]] study on [[nuclear winter]] that [[Kuwaiti oil fires|massive oil well fires in Kuwait]] would cause significant effects on climate was incorrect.<ref name="Wilmington morning Star">{{cite news |url=https://news.google.com/newspapers?id=6tEVAAAAIBAJ&pg=6851,2148654&dq=world-climate-conference+oil+fires&hl=en |title=Burning oil wells could darken U.S. skies |last=Evans |first=David |work=Wilmington Morning Star |date=January 21, 1991 |access-date=December 22, 2019 }}{{Dead link|date=April 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref>Sagan, Carl (1996). The Demon-Haunted World: Science as a Candle in the Dark. New York: Random House. p. 257. {{ISBN|978-0-394-53512-8}}</ref>

In January 1999, contrarian [[Patrick Michaels]] wrote a commentary offering to "take even money that the 10 years ending on December 31, 2007, will show a statistically significant global cooling trend in temperatures measured by satellite", on the basis of his view that record temperatures in 1998 had been a blip.<ref>{{Cite web|url=https://www.cato.org/publications/commentary/fighting-fire-facts|title=Fighting Fire With Facts|last=Michaels|first=Patrick J.|author-link=Patrick Michaels|date=January 18, 1999|publisher=[[Cato Institute]]|access-date=July 19, 2013}}</ref> Indeed, over that period, satellite-measured temperatures never again approached their 1998 peak. Due to a sharp but temporary dip in temperatures in 1999–2000, a least-squares linear regression fit to the satellite temperature record showed little overall trend. The RSS satellite temperature record showed a slight cooling trend,<ref>{{Cite web|title=RSS MSU lower trop. global mean |url=http://woodfortrees.org/plot/rss/from:1998.0/to:2008.0/plot/rss/from:1998.0/to:2008.0/trend |archive-url=https://web.archive.org/web/20140107051531/http://woodfortrees.org/plot/rss/from:1998.0/to:2008.0/plot/rss/from:1998.0/to:2008.0/trend |publisher=WoodForTrees |access-date=January 6, 2014 |archive-date=January 7, 2014 |url-status=dead}}</ref> but the UAH satellite temperature record showed a slight warming trend.<ref>{{Cite web|title=UAH NSSTC lower trop. global mean |url=http://woodfortrees.org/plot/uah/from:1998.0/to:2008.0/plot/uah/from:1998.0/to:2008.0/trend |archive-url=https://web.archive.org/web/20140107052029/http://woodfortrees.org/plot/uah/from:1998.0/to:2008.0/plot/uah/from:1998.0/to:2008.0/trend |publisher=WoodForTrees |access-date=January 6, 2014 |archive-date=January 7, 2014 |url-status=dead}}</ref>

==Twenty-first century==
In 2003, the [[Office of Net Assessment]] at the [[United States Department of Defense]] was commissioned to produce a study on the likely and potential effects of abrupt modern climate change should a [[shutdown of thermohaline circulation]] occur.<ref name="Schwartz2003">{{cite report|last1=Schwartz|first1=Peter |last2=Randall|first2=Doug|date=October 2003|title=An Abrupt Climate Change Scenario and Its Implications for United States National Security |url=http://www.climate.org/PDF/clim_change_scenario.pdf|archive-url=https://web.archive.org/web/20090320054750/http://www.climate.org/PDF/clim_change_scenario.pdf|archive-date=March 20, 2009|url-status=dead}}</ref> The study, conducted under ONA head [[Andrew Marshall (foreign policy strategist)|Andrew Marshall]], modelled its prospective climate change on the [[8.2 kiloyear event]], precisely because it was the middle alternative between the [[Younger Dryas]] and the [[Little Ice Age]]. Scientists said that "abrupt climate change initiated by [[Greenland ice sheet]] melting is not a realistic scenario for the 21st century".<ref name="Jungclaus2006">{{cite journal|last=Jungclaus |first=Johann H.|display-authors=etal|year=2006|title=Will Greenland melting halt the thermohaline circulation?|journal=[[Geophysical Research Letters]]|publication-date=September 7, 2006|volume=33|issue=17 |pages=L17708 |bibcode=2006GeoRL..3317708J|doi=10.1029/2006GL026815|hdl=11858/00-001M-0000-0011-FDB1-C|s2cid=20863612 |hdl-access=free}}</ref>

==Present level of knowledge==
{{Main|Next glacial period}}
The concern that cooler temperatures would continue, and perhaps at a faster rate, has been observed to be incorrect, as was assessed in the [[IPCC Third Assessment Report]] of 2001.<ref name="IPCC sci basis" /> More has to be learned about climate. However, the growing records have shown that short term cooling concerns have not been borne out.

As for the prospects of the end of the current interglacial, while the four most recent interglacials lasted about 10,000 years, the interglacial before that lasted around 28,000 years. Milankovitch-type calculations indicate that the present interglacial would probably continue for tens of thousands of years naturally in the absence of human perturbations.<ref>{{cite journal
 | date=June 10, 2004
 | title=Eight glacial cycles from an Antarctic ice core
 | journal=Nature
 | volume=429
 | issue=6992
 | pages=623–8
 | doi=10.1038/nature02599
 | last2=Barbante
 | first2=Carlo
 | last3=Barnes
 | first3=Piers R. F.
 | last4=Marc Barnola
 | first4=Jean
 | last5=Bigler
 | first5=Matthias
 | last6=Castellano
 | first6=Emiliano
 | last7=Cattani
 | first7=Olivier
 | last8=Chappellaz
 | first8=Jerome
 | last9=Dahl-Jensen
 | first9=Dorthe
 | last10=Delmonte
 | first10=Barbara
 | last11=Dreyfus
 | first11=Gabrielle
 | last12=Durand
 | first12=Gael
 | last13=Falourd
 | first13=Sonia
 | last14=Fischer
 | first14=Hubertus
 | last15=Flückiger
 | first15=Jacqueline
 | last16=Hansson
 | first16=Margareta E.
 | last17=Huybrechts
 | first17=Philippe
 | last18=Jugie
 | first18=Gérard
 | last19=Johnsen
 | first19=Sigfus J.
 | last20=Jouzel
 | first20=Jean
 | last21=Kaufmann
 | first21=Patrik
 | last22=Kipfstuhl
 | first22=Josef
 | last23=Lambert
 | first23=Fabrice
 | last24=Lipenkov
 | first24=Vladimir Y.
 | last25=Littot
 | first25=Geneviève C.
 | last26=Longinelli
 | first26=Antonio
 | last27=Lorrain
 | first27=Reginald
 | last28=Maggi
 | first28=Valter
 | last29=Masson-Delmotte
 | first29=Valerie
 | last30=Miller
 | first30=Heinz
 | pmid=15190344 |bibcode = 2004Natur.429..623A | display-authors=8
 | last1 = Augustin|first1 = L.| doi-access=free
}}</ref> Other estimates (Loutre and Berger, based on orbital calculations) put the unperturbed length of the present interglacial at 50,000 years.<ref>{{cite journal|last1=Berger|first1=A.|last2=Loutre|first2=M. F.|title=An Exceptionally Long Interglacial Ahead?|journal=Science|date=August 23, 2002|volume=297|issue=5585|pages=1287–8|doi=10.1126/science.1076120|pmid=12193773|s2cid=128923481}}</ref> A. Berger expressed the opinion in 2005 (EGU presentation) that the present CO<sub>2</sub> perturbation will last long enough to suppress the next glacial cycle entirely. This is consistent with the prediction of [[David Archer (scientist)|David Archer]] and colleagues who argued in 2005 that the present level of {{CO2}} will suspend the next glacial period for the next 500,000 years and will be the longest duration and intensity of the projected interglacial period and are longer than have been seen in the last 2.6 million years.<ref>{{Cite journal|last1=Archer|first1=David|last2=Ganopolski|first2=Andrey|title=A Movable Trigger Fossil Fuel CO2 and the Onset Of The Next Glaciation|journal=Geochemistry, Geophysics, Geosystems|date=May 5, 2005|volume=6|issue=5|pages=Q05003|doi=10.1029/2004GC000891|bibcode=2005GGG.....6.5003A|doi-access=free}}</ref>

A 2015 report by the Past Global Changes Project, including Berger, says simulations show that a new glaciation is unlikely to happen within the next approximately 50,000 years, before the next strong drop in Northern Hemisphere summer insolation occurs "if either atmospheric {{CO2}} concentration
remains above 300 ppm or cumulative carbon emissions exceed 1000 Pg C" (i.e. 1000 gigatonnes carbon). "Only for an atmospheric {{CO2}} content below the preindustrial level may a glaciation occur within the next 10 ka. ... Given the continued anthropogenic {{CO2}} emissions, glacial inception is very unlikely to occur in the next 50 ka, because the timescale for {{CO2}} and temperature reduction toward unperturbed values in the absence of active removal is very long [IPCC, 2013], and only weak precessional forcing occurs in the next two precessional cycles." (A [[Milankovitch cycles#Apsidal precession|precessional cycle]] is around 21,000 years, the time it takes for the [[perihelion]] to move all the way around the [[tropical year]].)<ref>{{Cite journal|last=Interglacial Working Group Of PAGES|title=Interglacials Of The Last 800,000 years |url=http://discovery.ucl.ac.uk/1474024/1/Past%20Interglacials%20Working%20Group%20of%20PAGES%20Interglacials%20of%20the%20last%20800%2C000%20years%20VoR.pdf|journal=Reviews of Geophysics|date=November 20, 2015|volume=54|issue=1|pages=162–219|bibcode=2016RvGeo..54..162P|doi=10.1002/2015RG000482|hdl=2078.1/175429|doi-access=free}}* [[File:CC-BY icon.svg|50px]] Text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 (CC BY 3.0)] license.
</ref>

As the NAS report indicates, scientific knowledge regarding climate change was more uncertain than it is today. At the time that Rasool and Schneider wrote their 1971 paper, climatologists had not yet recognized the significance of greenhouse gases other than water vapor and carbon dioxide, such as [[methane]], [[nitrous oxide]], and [[chlorofluorocarbon]]s.<ref>{{cite web | title=Other Greenhouse Gases | work=The Discovery of Global Warming | author=Weart, Spencer | url=http://www.aip.org/history/climate/othergas.htm | access-date=November 17, 2005 | archive-date=January 7, 2003 | archive-url=https://web.archive.org/web/20030107161816/http://www.aip.org/history/climate/othergas.htm | url-status=dead }}</ref> Early in that decade, carbon dioxide was the only widely studied human-influenced greenhouse gas. The attention drawn to atmospheric gases in the 1970s stimulated many discoveries in subsequent decades. As the temperature pattern changed, global cooling was of waning interest by 1979.<ref name="wcc-1979.html"/>

==The ice age fallacy==
A common argument used to [[Climate change denial|dismiss the significance of human-caused climate change]] is to allege that scientists showed concerns about global cooling which did not materialise, and there is therefore no need to heed current scientific concerns about global warming.<ref name="Time 16713">{{cite magazine|url=https://science.time.com/2013/06/06/sorry-a-time-magazine-cover-did-not-predict-a-coming-ice-age/|title=Sorry, a Time Magazine Cover Did ''Not'' Predict a Coming Ice Age|last=Walsh|first=Bryan|date=June 6, 2013|access-date=July 16, 2013|magazine=Time |quote=Call it the Ice Age Fallacy.&nbsp;... global cooling was much more an invention of the media than it was a real scientific concern. A survey of peer-reviewed scientific papers published between 1965 and 1979 shows that the large majority of research at the time predicted that the earth would warm as carbon-dioxide levels rose – as indeed it has.}}</ref> In a 1998 article promoting the [[Oregon Petition]], [[Fred Singer]] argued that expert concerns about global warming should be dismissed on the basis that what he called "the same hysterical fears" had supposedly been expressed earlier about global cooling.<ref>{{cite web|url=http://sepp.org/glwarm/sciaddheat.html|title=Scientists add to heat over global warming|last=Singer|first=S. Fred|date=May 5, 1998|archive-url=https://web.archive.org/web/20051119045242/http://sepp.org/glwarm/sciaddheat.html|archive-date=November 19, 2005|access-date=November 19, 2005}}</ref>
 
Bryan Walsh of ''[[Time (magazine)|Time]]'' magazine (2013) calls this argument "the Ice Age Fallacy". Illustrating the argument, for several years an image had been circulated of a ''Time'' cover, supposedly dated 1977, showing a penguin above a cover story title "How to Survive the Coming Ice Age". In March 2013, ''[[The Mail on Sunday]]'' published an article by [[David Rose (journalist)|David Rose]], showing this same cover image, to support his claim that there was as much concern in the 1970s about a "looming 'ice age{{'"}} as there was now about global warming.<ref>{{Cite web|url=http://viewfrommidamerica.blogspot.co.uk/2010/09/from-global-cooling-to-global-cooling.html|title=From Global Cooling to Global Cooling|date=September 30, 2010|work=The View From Mid-America|access-date=July 16, 2013}}</ref> After researching the authenticity of the magazine cover image, in July 2013, Walsh confirmed that the image was a hoax, modified from a 2007 cover story image for "The Global Warming Survival Guide".<ref name="Time 16713" />

== See also ==
{{Div col|colwidth=18em}}
* [[Anti-greenhouse effect]]
* [[Global dimming]]
* [[Land surface effects on climate]]
* [[Global warming]]
* [[History of climate change science]]
* [[Volcanic winter]]
* [[Next glacial maximum]]
* ''[[The Day After Tomorrow]]''
* [[Ice age]]
{{Div col end}}

== References ==
{{Reflist|30em}}

==Further reading==
* {{cite web | title=The Climate Record: The Last Several Centuries and Last Several Decades. Is the Climate Stable? | work=ENVI2150 Climate Change: Scientific Issues |author= Carslaw, K. S. | url=http://www.env.leeds.ac.uk/envi2150/oldnotes/lecture7/lecture7.html | access-date=November 17, 2005 |archive-url=https://web.archive.org/web/20070220140144/http://www.env.leeds.ac.uk/envi2150/oldnotes/lecture7/lecture7.html |archive-date=February 20, 2007}}
* {{cite web | title=History of Continental Drift - Before Wegener | author=unknown | url=http://www.bbm.me.uk/portsdown/PH_061_History_a.htm | access-date=November 17, 2005 | url-status=dead | archive-url=https://web.archive.org/web/20051123101326/http://www.bbm.me.uk/portsdown/PH_061_History_a.htm | archive-date=November 23, 2005}}
* http://tvnews.vanderbilt.edu/program.pl?ID=52903 Vanderbilt Television News Archive
* {{cite web |first=Scott K. |last=Johnson | title=That '70s myth—did climate science really call for a "coming ice age?" | website=Ars Technica | date=June 7, 2016 | url=https://arstechnica.com/science/2016/06/that-70s-myth-did-climate-science-really-call-for-a-coming-ice-age/ | ref={{sfnref | Ars Technica | 2016}} | access-date=June 8, 2019}}

== External links ==
* [https://skepticalscience.com/ice-age-predictions-in-1970s-intermediate.htm What were climate scientists predicting in the 1970s?], summaries for laypeople of research and conspiracy theories by [[Skeptical Science]], described by the marine biologist Ove Hoegh-Guldberg "the most prominent knowledge-based website dealing with climate change in the world". 
* [http://www.wmconnolley.org.uk/sci/iceage/ Discussion and quotes from various papers about the "1970s prediction of an imminent ice age"], by Wm Connolley
* [https://web.archive.org/web/20030103043344/http://www.icsu-scope.org/downloadpubs/scope13/foreword.html SCOPE 13 - The Global Carbon Cycle], [[Scientific Committee on Problems of the Environment|SCOPE]], 1976.
* [https://web.archive.org/web/20030103114142/http://www.icsu-scope.org/downloadpubs/scope27/preface.html SCOPE 27 - Climate Impact Assessment], 1984.
* {{cite magazine |title=Another Ice Age? |url=http://www.time.com/time/printout/0,8816,944914,00.html |archive-url=https://web.archive.org/web/20070312061339/http://www.time.com/time/printout/0,8816,944914,00.html |url-status=dead |archive-date=March 12, 2007 |magazine=Time |date=June 24, 1974}}
* {{cite journal |vauthors=Chambers FM, Brain SA |title=Paradigm shifts in late-Holocene climatology? |journal=The Holocene |volume=12 |issue=2 |pages=239–249 |year=2002 |doi=10.1191/0959683602hl540fa |bibcode=2002Holoc..12..239C |s2cid=128774561}}
*[http://www.saveportland.com/Climate/index.html Past Climate Change Beliefs] - some newspaper scans
* [http://www.climatemonitor.it/wp-content/uploads/2009/12/1974.pdf A Study of Climatological Research as it Pertains to Intelligence Problems] - CIA report from 1974
* [https://apps.dtic.mil/sti/pdfs/ADA204483.pdf Geohydrological implications of climate change on water resource development], C. W. Stockton and W. R. Boggess, Contract Report DACW 72-78-C-0031, for U. S. Army Coastal Engineering Res. Center, Fort Belvoir, Virginia, C. W. Stockton & associates, Tucson, May 15, 1979. (See p.&nbsp;159)
{{Global warming}}

{{DEFAULTSORT:Global Cooling}}
[[Category:1970s in science]]
[[Category:Climate change]]
[[Category:Obsolete scientific theories]]

[[sv:Global uppvärmning#Terminologi]]