Global cooling

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. And some of those global-cooling projections were based on the idea that aerosol levels in the atmosphere — which are a product of air pollution from sources like coal burning and which contribute to cooling by deflecting sunlight in the atmosphere — would keep rising. But thanks to environmental legislation like the Clean Air Acts, global air-pollution levels — not including greenhouse gases like carbon dioxide — peaked in the 1970s and began declining.
The reality is that scientists in the 1970s were just beginning to understand how climate change and aerosol pollution might impact global temperatures. Add in the media-hype cycle — which was true then as it is now — and you have some coverage that turned out to be wrong. But thanks to the Internet, those stories stay undead, recycled by notorious climate skeptics like George Will. Pay no attention to the Photoshop. It’s the science we should heed — and the science says man-made climate change is real and very, very worrying.

2 thoughts on “Global cooling

  1. shinichi Post author

    Sorry, a TIME Magazine Cover Did Not Predict a Coming Ice Age

    by Bryan Walsh

    https://time.com/5670942/time-magazine-ice-age-cover-hoax/

    The newsmagazine business isn’t what it used to be. (Though, hey, it could be worse.) But the space between the red borders of TIME magazine remains some of the most valuable real estate in the news industry. You can tell by how often doctored TIME covers show up in protest crowds, movies, TV shows and on the Web. Former TIME International editor Jim Frederick even had a copy of this fake TIME from the video game Call of Duty 3 hanging up in his office — a fact that drove me insane with jealousy.

    Ads, jokes and protests are one thing, though — hoax covers are something else entirely. And that’s the problem with a faked TIME cover about global warming that’s been floating around the Internet for some time. (Hat tip to the science blogger David Kirtley, who posted on this a couple of days ago.) You can see it here.

    The cover on the right is real. (I should know — I wrote the story about China and India that’s mentioned in the subhead.) The one on the left is very much not. It’s a doctored version of this cover, from 2007:

    Apparently the hoax cover has been floating around the Internet for at least a few years. I’m not sure who created it, and it doesn’t seem to have gotten a whole lot of traction, even among climate-science deniers. Though kudos to whoever initially put the fake cover together. That’s some pretty good photoshopping.

    But the hoax does touch on an important part of climate science — and one that’s often misunderstood by skeptics. Call it the Ice Age Fallacy. Skeptics argue that back in the 1970s both popular media and some scientists were far more worried about global cooling than they were about global warming. For some reason a Newsweek article on the next ice age, published back in 1975, gets a lot of the attention, though TIME did a version of the story, as did a number of other media outlets. The rationale goes this way: the fact that scientists were once supposedly so concerned about global cooling, which didn’t come true, just shows that we shouldn’t worry about the new fears of climate change.

    But as John Cook points out over at Skeptical Science, 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. And some of those global-cooling projections were based on the idea that aerosol levels in the atmosphere — which are a product of air pollution from sources like coal burning and which contribute to cooling by deflecting sunlight in the atmosphere — would keep rising. But thanks to environmental legislation like the Clean Air Acts, global air-pollution levels — not including greenhouse gases like carbon dioxide — peaked in the 1970s and began declining.

    The reality is that scientists in the 1970s were just beginning to understand how climate change and aerosol pollution might impact global temperatures. Add in the media-hype cycle — which was true then as it is now — and you have some coverage that turned out to be wrong. But thanks to the Internet, those stories stay undead, recycled by notorious climate skeptics like George Will. Pay no attention to the Photoshop. It’s the science we should heed — and the science says man-made climate change is real and very, very worrying.

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  2. shinichi Post author

    Global cooling

    from Wikipedia

    https://en.wikipedia.org/wiki/Global_cooling

    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 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.

    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.

    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. The study, conducted under ONA head 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”.

    Present level of knowledge

    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. 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. Other estimates (Loutre and Berger, based on orbital calculations) put the unperturbed length of the present interglacial at 50,000 years. Berger (EGU 2005 presentation) thinks that the present CO2 perturbation will last long enough to suppress the next glacial cycle entirely. This is entirely consistent with David Archer’s and colleague’s prediction who argue 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.

    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 chlorofluorocarbons. 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.

    The ice age fallacy

    A common argument used to 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. 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.

    Bryan Walsh of 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, 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. 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”.

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