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It's the sun
Climate's changed before
There is no consensus
Surface temp is unreliable
Models are unreliable
It's cooling
Ice age predicted in the 70's
Al Gore got it wrong
CO2 lags temperature
We're heading into an ice age
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Scientists predicted an impending ice age in the 1970's

The skeptic argument...

The first Earth Day was celebrated on April 22, 1970, amidst hysteria about the dangers of a new ice age. The media had been spreading warnings of a cooling period since the 1950s, but those alarms grew louder in the 1970s... In 1975, cooling went from “one of the most important problems” to a first-place tie for “death and misery.” The claims of global catastrophe were remarkably similar to what the media deliver now about global warming (source: Fire and Ice).

What the science says...

1970's ice age predictions were predominantly media based with the majority of scientific papers predicting warming.

The notion that the 1970's scientific consensus was for impending global cooling is incorrect. In actuality, there were significantly more papers in the 1970's predicting warming than cooling.

Scientific studies in the 1970's re global cooling

Most predictions of an impending ice age came from the popular press (eg - Newsweek, NY Times, National Geographic, Time Magazine). As far as peer reviewed scientific papers in the 1970's, very few papers (7 in total) predicted global cooling. What surprises is that even in the 1970's, on the back of 3 decades of global cooling, significantly more papers (42 in total) predicted global warming due to CO2. More on 1970's science...


Figure 1: Number of papers classified as predicting global cooling (blue) or warming (red). In no year were there more cooling papers than warming papers (Peterson 2008).

Rasool and Schneider's ice age "projection"

The main study cited by skeptics is Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate (Rasool 1971). The paper doesn't actually predict an ice age. Instead, it projects a possible scenario - if aerosol levels increased 6 to 8 times then sustained those levels for several years, it may trigger an ice age. Historically, what happened was aerosol levels fell. While it's unclear whether Rasool's calculations re aerosol cooling were accurate, one inaccuracy was they underestimated climate's sensitivity to CO2 by a factor of 3.

In the decades since their 1971 paper, many studies constraining climate sensitivity calculate that if atmospheric CO2 was doubled, global temperatures would rise around 3°C. These studies employ different methods (modelling, calculations from empirical observations) looking at different time periods (the 20th century, the Holocene, past ice ages), different aspects of climate (surface temperature, mid-tropospheric temperature, ocean heat intake) and response to different forcings (volcanic, CO2, solar). More on climate sensitivity...

National Academy of Sciences - now and then

The most comprehensive study on the subject (and the closest thing to a scientific consensus at the time) was the 1975 US National Academy of Sciences/National Research Council Report. Their basic conclusion was "…we do not have a good quantitative understanding of our climate machine and what determines its course. Without the fundamental understanding, it does not seem possible to predict climate…"

Contrast this with the US National Academy of Science's current position: "there is now strong evidence that significant global warming is occurring... It is likely that most of the warming in recent decades can be attributed to human activities... The scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action." This is in a joint statement with the Academies of Science from Brazil, France, Canada, China, Germany, India, Italy, Japan, Russia and the United Kingdom.

Other indications of current consensus

Other scientific bodies that have released statements endorsing anthropogenic global warming include:

None of these bodies (at least the ones that existed back then) endorsed ice age predictions in the 70's. More on scientific consensus...

So global cooling predictions in the 70's amounted to media and a handful of studies, even then outweighed by global warming predictions. Today, an avalanche of studies and overwhelming scientific consensus endorse anthropogenic global warming. To compare cooling predictions in the 70's to the current situation is both inappropriate and misleading.

Further reading

Comments

  1. But the idea that we will go into another glaciation is far sounder science than is this new and basically baseless stuff. We always have in the past. This planet is currently hard-wired with a one way catastrophic cooling bias.

    The case that we will have another glaciation is basically cut and dried. We have the capacity to cool the earth. We have no such capacity to warm the earth. In order to avoid another glaciation we ought to be looking at ways to hose down volcanic aerosols or something.

    Certainly we need to build up our nuclear energy production capacity. And our hydrocarbons as well.
  2. Ice ages cannot be explained without the GHG feedback. The same science that tells us this, tells us we are heating up the planet.
  3. The claim by Peterson that there were only 7 papers in the 1970s predicting cooling is just ridiculous. Anyone can check this with a quick look at Google scholar. Here are two examples they have missed, but there are many more.

    Return of the ice age and drought in peninsular Florida?
    Joseph M. Moran, Geology 3 (12): 695-696 (1975)
    Convection in the Antarctic Ice Sheet Leading to a Surge of the Ice Sheet and Possibly to a New Ice Age
    T. Hughes, Science Vol. 170. no. 3958, pp. 630 - 633 (1970)

    What is strange is why people attempt to re-write recent history in this way, when their claims can so easily be disproven.
    Where did all the stories in the papers, TV and magazines come from? Were they all just fabricated? No of course not, they came from scientists who made suggestions (like the above 'possibly to a new ice age') which were then hyped and exaggerated by the media. Much the same thing is happening now with the global warming scare.
  4. Um, for one thing Moran was writing about _Florida_ cooling, not _global_ cooling. I guess you'll need to relax your search criterion for "global cooling" a whole lot to prove that scientists did predict cooling...

    "they came from scientists who made suggestions (like the above 'possibly to a new ice age') which were then hyped and exaggerated by the media. Much the same thing is happening now with the global warming scare."

    Yeah, "much of the same thing" in the sense that the "media" is artificially inflating the voice of the global warming "skeptics".
  5. frankbi
    Read the media articles, they are almost always alarmist. Those that have comment sections often disappear after someone disproves the article. I have seen this on CBS, ABC and LiveScience quite a few times.
    Then there is the BBC.
  6. PaulM,
    You bemoan people attempting to [quote]‘re-write recent history’. However, reporting the facts does not amount to ‘rewriting history’!
    The people actually responsible for the rewriting of history are not AGW fanatics, but people politically or ideologically aligned to industry and typically funded directly or indirectly by the fossil fuel funded denial industry. Peterson et al. 2008 have merely attempted to establish the facts and set the record straight.

    The fact that you may have identified two additional relevant papers and claimed there are ‘many more’, which may or may not support your pet theory, does not invalidate their research. It seems probable that any additional papers fitting the various search criteria will be distributed in much the same way as the papers already listed, unless there is a very good reason why they should not be included.
  7. Quietman
    You are repeating the deceitful alarmist allegations made repeatedly by skeptics

    From Scientists add to heat over global warming by S. Fred Singer
    Washington Times, May 5, 1998
    “But this exaggerated concern about global warming contrasts sharply with an earlier NAS/NRC report, "Understanding Climate Change: A Program for Action." There, in 1975, the NAS "experts" exhibited the same hysterical fears—-this time, however, asserting a "finite possibility that a serious worldwide cooling could befall the Earth within the next 100 years."

    The 1975 NAS panel claimed to have good reason for their fears: Global temperatures had been in steady decline since the 1940s. They considered the preceding period of warming, between 1860 and 1940, as "unusual," following as it did the "Little Ice Age," which had lasted from 1430 to 1850.”

    http://www.sepp.org/key%20issues/glwarm/sciaddheat.html

    You will note that the terms ‘exaggerated’, ‘hysterical fears’ and ‘fears’ are used. There are a number of other changes too that render the use of quotes highly questionable.

    1975 US National Academy of Sciences/National Research Council Report
    UNDERSTANDING CLIMATE CHANGE: A program for action

    Strangely,

    From the foreword (by V E Suomi, Chair of the US Committee for GARP):

    "..,we do not have a good quantitative understanding of our climate machine and what determines its course. Without the fundamental understanding, it does not seem possible to predict climate..,".

    From the introduction
    "Climatic change has been a subject of intellectual interest for many years. However, there are now more compelling reasons for its study: the growing awareness that our economic and social stability is profoundly influenced by climate and that man's activities themselves may be capable of influencing the climate in possibly undesirable ways. 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".

    Not much evidence of hysteria! It would seem that the allegations of exaggeration and hysteria were complete fabrications introduced by Singer. The measured and cautious language of the National Academy of Sciences has been entirely born out.
  8. Re: "You are repeating the deceitful alarmist allegations made repeatedly by skeptics"
    No, I am not repeating anything. My statement is purely from personal experience. I tried again this morining, after reading your reply, to go back and see if some of the alarmist articles were still there. Most were gone. I checked back through January - gone. What few skeptical articles I had read are still there. I may be ignorant about many subjects but I am not stupid. Those articles were intentionally pulled when proven incorrect. Here are the few that have not been deleted:

    The rhetoric of climate and slavery

    Climate change 2007 - a year in review

    Trees absorbing less CO2 as world warms, study finds

    Acidic seas may kill 98% of world's reefs by 2050

    Deniers of global warming harm us

    Global warming to trigger volcanic eruptions
  9. These articles all present a case for either natural warming or non-CO2 forced AGW, or simply that the alarmist claims don't quite cut it.

    Water Vapor Feedback Is Rapidly Warming Europe

    About the coral reefs: Coral Reefs May Be More Resilient Than Expected

    "The deniers' fallback position is to argue that what is happening is due not to human intervention but some sort of natural cycle." During the last centuries human methane emissions artificially increased CH4 concentrations to approximately 1750 ppbv:
    Current Spike In Atmospheric Methane Mirrors Early Climate Change Events
    NASA Studies How Airborne Particles Affect Climate Change

    "Tropical deforestation currently accounts for roughly one-fifth of the global emissions of carbon dioxide, the most important human-derived greenhouse gas, Gurney said."
    Researchers Propose Way To Incorporate Deforestation Into Climate Change Treaty

    "Whilst rising air temperatures are believed to be the primary cause of recent dramatic disintegration of ice shelves like Larsen B, the new study suggests that the ocean may play a more significant role in destroying them than previously thought."
    Antarctic Ice Shelf Retreats Happened Before
    Antarctic Deep Sea Gets Colder

    My point being that healthy skepticism leads to better understanding of the big picture.
    [ Response: I'll leave this comment up as there are few links there I wasn't previously aware of. But from now on, I'm taking a zero tolerance policy on comments that post a bunch of links not related to the topic. I know its a bit more work but please post any links on the relevant page. ]
  10. Sorry John
    I was replying to ScaredAmoeba "You are repeating the deceitful alarmist allegations made repeatedly by skeptics" Attempting to show that not all skeptical arguments are denials or harmful. If you prefer to delete it thats OK by me, it's your blog.
    [ Response: Nah, I'll leave it up. One of my pet peeves when having online discussion about global warming is when someone just posts a whole bunch of diverse links to a wide range of topics - it essentially shuts down the discussion because it's not practical to post a reply addressing each link. More constructive debate keeps to the topic at hand. I don't think you were necessarily trying to do this but for future reference, those links would be more effective posted on the appropriate page. Plus from my point of view as webmaster, I like the comments section to be relevant and useful to readers. ]

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© John Cook 2008