Just 20 Years

I wanted to pull out one thought from my longer video and presentation on global warming.

As a reminder, I adhere to what I call the weak anthropogenic theory of global warming — that the Earth’s sensitivity to CO2, net of all feedback effects, is 1C per doubling of CO2 concentrations or less, and that while man may therefore be contributing to global warming with his CO2 (not to mention his land use and other practices) the net effect falls far short of catastrophic.

While in the media, alarmists want to imply that the their conclusions about climate sensitivity are based on a century of observation, but this is not entirely true.  Certainly we have over a century of temperature measurements, but only a small part of this history is consistent with the strong anthropogenic theory.  In fact, I observed in my video is that the entire IPCC case for a high climate sensitivity to CO2 is based on just 20 years of history, from about 1978 to 1998.

Here are the global temperatures in the Hadley CRUT3 data base, which is the primary data from which the IPCC worked (hat tip Junk Science Global Warming at a Glance)  click to enlarge

Everything depends on how one counts it, but during the period of man-made CO2 creation, there are really just two warming periods, if we consider the time from 1910 to 1930 just a return to the mean.

  • 1930-1952, where temperatures spiked about a half a degree and ended 0.2-0.3 higher than the past trend
  • 1978-1998, where temperatures rose about a half a degree, and have remained at that level since

Given that man-made CO2 output did not really begin in earnest until after 1950 (see the blue curve of atmospheric CO2 levels on the chart), even few alarmists will attribute the runup in temperatures from 1930-1952 (a period of time including the 1930’s Dust Bowl) to anthropogenic CO2.  This means that the only real upward change in temperatures that could potentially be blamed on man-made CO2 occurred from 1978-1998.

This is a very limited amount of time to make sweeping statements about climate change causation, particularly given the still infant-level knowledge of climate science.  As a result, since 1970, skeptics and alarmists have roughly equal periods of time where they can make their point about temperature causation (e.g. 20 years of rising CO2 and flat temperatures vs. 20 years of rising CO2 and rising temperatures).

This means that in the last 40 years, both skeptics and alarmists must depend on other climate drivers to make their case  (e.g. skeptics must point to other natural factors for the run-up in 1978-1998, while alarmists must find natural effects that offset or delayed warming in the decade either side of this period).  To some extent, this situation slightly favors skeptics, as skeptics have always been open to natural effects driving climate while alarmists have consistently tried to downplay natural forcing changes.

I won’t repeat all the charts, but starting around chart 48 of this powerpoint deck (also in the video linked above) I present some alternate factors what may have contributed, along with greenhouse gases, to the 1978-1998 warming (including two of the strongest solar cycles of the century and a PDO warm period nearly exactly matching these two decades).

Postscript: Even if the entire 0.7C or so temperature increase in the whole of the 20th century is attributed to manmade CO2, this still implies a climate sensitivity FAR below what the IPCC and other alarmists use in their models.   Given about 44% of a doubling since the industrial revolution began in CO2 concentrations, this would translate into a temperature sensitivity of 1.3C  (not a linear extrapolation, the relationship is logarithmic).

This is why alarmists must argue that not only has all the warming we have seen been due to CO2 ( heroic assumption in and of itself) but that there are additional effects masking or hiding the true magnitude of past warming.  Without these twin, largely unproven assumptions, current IPCC “consensus” numbers for climate sensitivity would be absurdly high.  Again, I address this in more depth in my video.

177 thoughts on “Just 20 Years”

  1. Renewable Guy,

    Please show me the “Report 2” at the UN. “About.com” is not a reference. Don’t DISS on the Pachy.

    Here, start here:

    …and point to the nonsense that Rolling Stone and Skeptical Science TOLD you to regurgitate. If you are having issue with that, here is an assist along netdr’s list.


    Regardless of the issues at play, renewables (and AGW, climate disruption, whatever) are NONsense in the foreseeable future, unless it is nuclear. People do not trust Greenpeace and WWF anymore. You manipulate with less than half truths. Let the REAL greens (Mark Lynas, George Moinbat etc) step up before your types put the planet in jeopardy with geo-engineering, bigger bird choppers, etc.

    Besides, you never answered my inquiry.

  2. kelly liddle:
    the scientists who we now refer to as flat earthers were also the most qualified


    Maybe you should visit the Heartland Institute. They hire scientists to tell you the story you want to hear.

  3. ntrepid_wanders:
    Renewable Guy,

    Please show me the “Report 2″ at the UN. “About.com” is not a reference. Don’t DISS on the Pachy.

    Here, start here:


    YOu have chosen what you want to believe.

    When the temperature of the earth increases due to co2, there are consequences. Having people gifted in science assist me in understanding global warming is fair game. Just as you may have Anthony Watts assist you in resisting AGW. I’m not resisting AGW, you are. And that takes energy on your part and stories of how all this just ain’t so. And they are just stories, not well studied evidence.

  4. intrepid_wanders:


    The director of the National Snow and Ice Data Centre, Mark Serreze, and his team have studied the Arctic for over 20 years. He explains: “We’re now committed to an ice-free Arctic in the summer – there’s just too much carbon dioxide in the atmosphere and the planet’s getting too warm. We’ve crossed a tipping point.”


    A climate tipping point is a point when global climate changes from one stable state to another stable state, in a similar manner to a wine glass tipping over. After the tipping point has been passed, a transition to a new state occurs. The tipping event may be irreversible, comparable to wine spilling from the glass—standing up the glass will not put the wine back.


    Do you have a better explanation for why the ice is melting all over the world?

    Why the sea level is rising?

    Do you know what polar amplification is? Do you think its happening or just a bunch of well studied, peer reviewed bunk?

    We have passed a tipping point in the artic and are now commited to ice free summers in the future. This is from a guy who has studied ice fhe past 20 years. Maybe Anthony Watts can come up with an answer for you. The ice free summers change how our climate works and there will be changes in our weather based on that.

    Maybe you can tell me why this individual scientist is an idiot from your point of view.

  5. Ted


    No scientific body of national or international standing has maintained a dissenting opinion; the last was the American Association of Petroleum Geologists, which in 2007 updated its 1999 statement rejecting the likelihood of human influence on recent climate with its current non-committal position.[2][3] Some other organizations, primarily those focusing on geology, also hold non-committal positions.


    The geologists work for oil companies. All other science organizations uphold AGW.

    Now the Pope upholds AGW.

  6. Renewable Guy:
    “YOu have chosen what you want to believe.”

    No. Your ilk chose the narrative and ruined the entire movement. The Greenpeace stance on nuclear is NON-SENSE (None, Zip, Zero), in a Carbon Reduction Program. That irrational response is responded to in kind. I am personally interested in what is going to power your I-pad. As you DISS on Watts, have you noted what kind of car you are driving?


    Yeah, he had those rightest tenancies that you like to exploit, but he attempting to be a human, are you?

    I find your your preferences of alliances to be dubious at best, but I am always willing to hear RATIONAL discussions. That means that Skeptical Science is just as annoying to me as Watts Up with That is to you.

    Yes, the earth is increasing in temperature. CO2 does increase the temperature. Sensitivity is only around 1.25deg/doubling CO2 based on empirical evidence (logarithmically falling off after saturation).

    This does not take too much energy. After the Montreal Treaty on O-zone depleting substance non-sense and the disappearance of the NH MWP, I was flat done with the current poor science. You can argue blue, but science is laughable now. It was not a mere 40 years ago. Real science was working.

    So, what “stories” are you going to spin next?

  7. Renewable Guy:

    You understand counter AGW better than AGW. How can you know its wrong if you ignor its observations?
    Not true.
    I know the arguments of the alarmists even better than they know them themselves.
    I was a true believer when I viewed “An Inconvenient Truth” and for about 6 months afterword but the more I read the less I believed.

    The verbal tap dance they do to explain how CO2 can lag temperature [after an ice age] and still be the cause of the temperature rise is laughable. That fiasco started my disbelief.

    I have read many books [and hundreds of papers] on climate science but my favorite one is “A Rough Guide….” by Henson. I have my own copy and use it to check out the sloppy science knowledge of the alarmists.

    For example:

    Most alarmists think that CO2 is a strong GHG. In fact it is very poor.

    Without feedbacks [which are likely negative] the computed temperature increase of a DOUBLING OF CO2
    is only 1 ° C. Ninety percent of the alarmists don’t know this fundamental concept. [The actual warming is likely much less than that. ]

    Several peer reviewed studies proved to me that the actual effect of water vapor is to reduce actual warming [Negative Feedback]. [Spencer and Braswell 2010]

    I am an engineer and have written computer models and know too much about the process to believe they can even estimate the temperature 20 let alone 100 years in the future. The present crop have “jumped the shark” badly starting the day they were published. Backcasting is a first step but believing it assures correct predictions is laughable.

    It has been shown that the more scientifically literate a person is the more likely they will be skeptical of CAGW.

  8. The continued use of “scientific consensus” as an argument is nonsense. You don’t determine whether water runs uphill or downhill by having a vote.

    The way to determine the validity of the AGW (or any other) HYPOTHESIS is by study and the accumulation of data. Obvious questions that anyone with a scientific or technical background would ask need to be answered, NOT shouted down. I was always happy to explain my work to questioners. I can’t imagine being offended if questions were raised. Hopefully, we all want the correct answers, rather than merely trying to justify our OPINIONS. This is particularly true with the AGW thing, as it calls for the destruction of our industrial economy. (No, there is no viable large scale “alternative energy”.)

    By the way, not ALL other scientific organizations uphold AGW. Maybe the Pope is a good cheerleader, as the AGW thing is more like a religion than OBJECTIVE science.

  9. renewable guy

    could you please tell me why the arctic is hot and the antarctic is cold as far as change goes as they are the most simular environments to compare. Hey to anyone who blogs here i like it because in a relative sense it is civil. so lets keep it that way.

  10. Hey kids! Been a while! Don’t mean to get entirely off topic, but I was wondering if anyone wanted to say anything about Willie Soon and Exxon?

  11. Contrary to the lies the Greenpeace spreads, fully disclosed. Non-issue.

    Greenpeace has now achieved a level of reproach that revivals the tobacco industry 😉

  12. Sure, blame Greenpeace “lies.” Glad to see the same levels or hypocrisy, doublethink, and denial still active at CS. I can only imagine what you would post if Jones et all were getting that much money from CRU–oh wait! The peeps here have opined frequently about the CRU crowd on just such charges.

    Actually, seems like a pretty big issue. Deny if you want.

  13. Hi Herbert, sorry–I thought I was being clear…but perhaps I am continuing an older conversation that I haven’t been a part of for a while.

    I think netdr’s response kind of makes my case. Willie Soon is an oft-quoted critic of climate change. He’s not a climate scientist per se but an astrophysicist and astronomer. He believes that climate change is a product of solar variation.

    Now, however, it has come to light that Soon has taken nearly $1M from several energy companies, Exxon among them, to do his research. Rather than admitting the conflict of interest, netdr comes out with some babble about “scientifically literate people” (who are apparently not the most scientifically literate people, the actual climate scientists involved) and blames the “alarmists,” entirely skirting the issue.

    In the past, the good people at CS have made many unproven allegations about climate scientists (Phil Jones and the CRU crew in particular)padding their pockets at the expense of legitimate science. This is an oversimplification but it is the gist. But, when someone like Soon (and he’s not the only critic) is exposed taking big money, CS and the gang of posters is predictably quiet…

    So, I hope that makes my point clearer.

    I’m reading netdr’s link; I’m not sure it makes exactly the case netdr thinks it does.

    And has anyone been able to track down the web addresses on Mr. Meyer’s “Junkscience” chart above?

  14. I gather then that the only people who are to be believed are those who have never had employment and never gotten a government (pro-AGW) grant. Oh, I forgot. Those that question the catastrophis AGW idea are automatically disbelieved. Only AGW pushers need offer their views.

  15. There are many scientists that don’t ride the CAGW bandwagon and aren’t being paid by Big Oil [Like CRU is]


    Climategate: CRU looks to “big oil” for support
    Posted on December 4, 2009 by Anthony Watts

    One of the favorite put-downs from people who think they have the moral high ground in the climate debate is to accuse skeptics with this phrase: “You are nothing but a shill for Big Oil”

    This sounds like a new version of lysenkoism to me. Those skeptical of Lysenkoism were branded shills for capitalism [big oil?].

    The climate change industry [including the US Government which seems to want to justify carbon taxes ] has funded almost all climate studies so far. I don’t see any difference between the objectivity of a climatologist studying climate change and a cigarette company scientist studying smoking.

    If a scientist accepts funding from Greenpeace, WWF, or NASA and doesn’t come up with scary predictions he won’t get the funds again will he ?

    A partial list of things caused by global warming.

    [Courtesy of the climate change industry.]

    Acne, Afghan poppies destroyed, African holocaust, aged deaths, poppies more potent, Africa devastated, Africa in conflict, African aid threatened, aggressive weeds, Air France crash, air pockets, air pressure changes, airport farewells virtual, airport malaria, Agulhas current, Alaskan towns slowly destroyed, Al Qaeda and Taliban Being Helped, allergy increase, allergy season longer, alligators in the Thames, Alps melting, Amazon a desert, American dream end, amphibians breeding earlier (or not), anaphylactic reactions to bee stings, ancient forests dramatically changed, animals head for the hills, animals shrink, Antarctic grass flourishes, Antarctic ice grows, Antarctic ice shrinks, Antarctic sea life at risk, anxiety treatment, algal blooms, archaeological sites threatened, Arctic bogs melt, Arctic in bloom, Arctic ice free, Arctic ice melt faster, Arctic lakes disappear, Arctic tundra lost, Arctic warming (not), a rose by any other name smells of nothing, asteroid strike risk, asthma, Atlantic less salty, Atlantic more salty, atmospheric circulation modified, attack of the killer jellyfish, avalanches reduced, avalanches increased, Baghdad snow, Bahrain under water, bananas grow, barbarisation, bats decline, beer and bread prices to soar, beer better, beer worse, beetle infestation, bet for $10,000, big melt faster, billion dollar research projects, billion homeless, billions face risk, billions of deaths, bird loss accelerating, bird populations dying, bird strikes, bird visitors drop, birds confused, birds decline (Wales), birds driven north, birds face longer migrations, birds return early, birds shrink(Aus), birds shrink (USA), bittern boom ends, blackbirds stop singing, blackbirds threatened, Black Hawk down

    Plus 1,000 more.

  16. Waldo: “I think netdr’s response kind of makes my case.”

    I understand what you are saying, but, without getting into the whole “he started this first” thing, I’d suggest that this argument isn’t about science, and thus it might make sense to discuss it separately. (I, for one, would leave that argument alone as I am much more interested in numbers and graphs.)

  17. Good point, Herbert. Although I might suggest that this site, CS, is much more about politics and ideology than it is about numbers and graphs. It’s about ideology hiding behind numbers and graphs that come from some dubious sources and are dealt with in a dubious manner

    So netdr, let’s deal with your post a point at a time:

    1) The Wattsup link is dead and I found at least two versions of the email on different sites, which is suspicious. I will not discount it, but I am suspicious.

    2) Did either Mike Kelly or CRU take money from Shell or BP? Neither email indicates that. The Kelly email sounds like he was helping a graduate student get funding for a project. The Mike Hulm email is unclear what he is taking about–he mentions some people that work for BP and Shell, but not what his relationship is with them or what their business is. Do you have any additional information?–because what Watts presents is a weakly supported allegation. Very typical.

    3) According to your last post, unless a climate scientist “come[s] up with scary predictions he won’t get the funds again will he ?” This is exactly the kind of unfounded allegation I referred to earlier. I don’t know–does a climate scientist need a scary scenario? Aren’t there a number of climate scientists without scary scenarios working in science? Even some that disagree with CAGW? Again, very typical.

    4) Do you have a double standard here? Is it acceptable for Soon to take money but not for CRU scientists?

    5) And finally, what about Willie Soon? Both you and Ted are deflecting your answers. Neither is apparently willing to say anything about Soon–you’d rather throw strawmen in the fire.

    Has anybody checked on the validity of Mr. Meyer’s original information for this post?

    I predict netdr will disappear now, as this was usual for him back in the day.

  18. I also am most interested in the poor arguments of the climate alarmists. Charts and graphs tell the story.

    The truth or falsity of the charges against Soon doesn’t interest me.

    The hundreds of Billions of dollars poured into the study of climate has created group of people with a vested interest in climate alarmism. If there is no CAGW then reduced budgets and for many no job. Groupthink is inevitable in that environment.

    Eisenhower should have warned us about the Climate Industrial Complex as well as the Military Industrial Complex.

    The alarmists need to have the strawman of “big oil” to blame their own inability to sell their mousemilk.

    BTW: The whatsup link is not dead and I just accessed it.

    At least for a change waldo isn’t playing Humpty Dumpty.

    When I use a word,’ Humpty Dumpty said, in rather a scornful tone, ‘it means just what I choose it to mean — neither more nor less.’

    Did you ever find a climate model that has predicted the last 12 years of non warming ?

    [If you need help deciding what a climate model is just ask.]

  19. You never did tell us what temperature the non climate model you cited predicted for 2000, through 2011 and how you arrived at those numbers.

    I predict that you never will.

  20. Watts’ link to the original email —


    –is dead.

    You have me confused with someone else re the “non climate model.” I have no idea what you are posting about.

    *****”The truth or falsity of the charges against Soon doesn’t interest me.”

    Of course you don’t, netdr, you are only interested in one thing and you are willing to ignore any information that doesn’t fit your prefab notions about climate science. You have some pretty good evidence that a climate denialist are on the take–but you will ignore it and submit unproven allegations about “groupthink.” This willful ignorance includes, say, the “charts and graphs” from any actual scientific body, anyone other than the Meyers and Watts of the world.

    Good to see things are still the same.

  21. Humpty

    Your writing style gives you away.

    BTW: the link:


    Works just fine.

    I read the original e-mails when they came out. The copied excerpts seem to be exactly what I read many months ago.

    The politics of why they aren’t freely available on the web right now is of no interest to me.

    [Conspiracy anyone?]

    Your alter ego can’t find a climate model which is even close to predicting the 1998 to present non warming. Can you do better?

    Dr Hansen’s 1988 model looked pretty good if the year were 2007. As of 2011 it looks terrible.


    The AR4 models have jumped the shark also.


    Investing tens of trillions of dollars because of the predictions of failed computer models is beyond dumb. [To use the technical term!]

    If there are any climate models which are doing well I would love to see them, but since they weren’t scary they were never published.

  22. Thanks Herbert.

    Rereading that email it sounds more and more as if Mick Kelly was searching for student money. Any additional information on the correspondence?

  23. Some regular posters on this blog should stop posting. Far too much rhetoric, too many shoddy conclusions based on scientific data and theory that you do not understand. There is a preponderance of bias fuelled by cherry-picking quotes and snippets of data from a variety of peer-reviewed and non peer-reveiwed sources to suit your own views. Utter tripe. If you want to add some intellectual weight to a difficult topic, go and take some courses on the subject and come back with knowledge and understanding – Don’t be a blog scientist. For example, “el nino/la nina, i.e. PDO” NO. ENSO is not the same as PDO, they are ocean systems controlled by different ocean dynamics on separate timescales and their impact on climate is very poorly understood. So when you say the ‘earth cooled while PDO was positive’, this is not a scientific statement, this is an opinion.

  24. …Revise that – When you say ‘From 1978 to 1998 there was a preponderance of El Nino’s over La Nina’s 11 to 2 and the temperature went up. [PDO was Positive and sunspots were maximum] No surprise there and no CO2 is required to explain it.’ This is half-baked stuff. For a start you must be very explicit in what you mean – La Nina and El Nino conditions are two extremes of the same oscillation and so both occur in equal ‘numbers’. Prolonged or extreme conditions can be classed as events. Then, we have to deal with your assertion that the temperature rise is an explicit result of this preponderance of extreme El Nino’s over La Nina’s. You cannot justify this, in fact noone has been able to justify this yet, ever. Next, “PDO was positive and sunspots were maximum” Again, more non-science. Making various assumptions that you have no right to, namely, assuming the PDO and sunspot cycles do have a measurable impact on temperature (whatever ‘temperature’ you are getting at, i assume average global surface) and then attributing their various states (positive or negative) to the temperature anomaly you are discussing. Very unconvinvcing. My point is, be wary of rhetoric, unfounded statements, opinions, half-baked conclusions and cherry picking. If you want to come to a discussion about the science, get yourself read – make a good peer-reviewed literature review and then come back with some intellectual weight. That is what real scientists have to do, even the ones who are skeptical of AGW.

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