Climate change 2013: the physical science basis

The IPCC have produced a good video about the recently released report of IPCC Working Group I. It explains the physical science basis of climate change in a very simple manner. Think of it as climate science for dummies in 9 minutes.

I have to thank Victor for bringing this to my attention. Victor is a climate scientist and his review of the video is that it is beautifully made with no obvious errors which is certainly good to know. 🙂 Thank you, Victor!

There are three key messages to take home:

*The warming in the climate system is unequivocal
*Human influence on the climate system is clear
*Continued greenhouse gas emissions will lock us into climate changes for centuries to come

Thomas Stoker (co-chair of IPCC Working Group I) says, “Therefore we conclude limiting climate change requires substantial and sustained reductions in greenhouse gases.”

The release of this video has been accompanied by the usual criticism from contrarian voices. In particular, people have accused the video of being alarmist and policy prescriptive. On the first charge I will say that climate change is alarming. However, the charge of alarmist can only apply if the dangers are exaggerated and causing needless panic. Firstly, I don’t see anyone in a panic about climate change – although possibly we should be – and secondly, if we accept that the video is accurate then it follows that it is not alarmist. If anything, I felt that the scientists who were videoed discussing observations, like sea level rise, all looked a bit blasé about it. I think what we really need here is a bit of healthy panic. 🙂

The second charge – that the video is prescriptive – relates to Stoker’s assessment that limiting climate change requires substantial and sustained reductions in greenhouse gases. Some people think that scientists should not step into the debate about policy solutions to climate change. I disagree with this on two levels. Firstly, I don’t think it’s prescriptive at all and secondly, even if it was, I want the professional opinion of scientists on how best to limit climate change. They are the ones who understand the problem better than anyone else and quite frankly I don’t trust politicians to understand and communicate the problem let alone dream up possible solutions to it.  It would be like getting a diagnosis from your doctor and then visiting your local MP for treatment suggestions. It just doesn’t work that way.

What can we do about? Probably the most effective solution is to divest or encourage your institution to divest from fossil fuels. See for more information. Politicians aren’t going to make the tough decisions unless they think it’s what we want.

43 thoughts on “Climate change 2013: the physical science basis

    1. Thanks, Bronwyn. Great article. I recently watched the movie, Greedy Lying Bastards which looked at the stranglehold just a few fossil fuel interest groups had on politics.

      Sorry to keep changing my wordpress theme. I’m still not happy with it so there may be another change before I get it right.

      1. I always enjoy the new ‘looks’. The one you have at the moment is nice. I like the new typeface. And thanks for the reference to Greedy Lying Bastards. As if the fossil fuel industry wouldn’t be going all out to look after their interests.

      2. That’s good to know. I am particular about what I want from my wordpress theme and I just couldn’t quite get it right. I think this one ticks all the boxes.

        I’m planning to offer my copy of Greedy Lying Bastards on my blog for anyone who is interested but probably only to people in the UK or Europe, sorry. You might be able to download a digital version from Amazon.

  1. I agree wholeheartedly. Only science can direct a way foreward, and there needs to be a greater sense of urgency. Any other approach is bound to fail and the consequences very lasting.

    1. I’m very happy to hear you say so, Graham. It seems crazy to me that scientists should be asked to communicate the problem but then remain mute on solutions. Aside from the fact that it is their democrat right to have an interest in political decisions, we also need them to tell us which solutions are going to be effective and which aren’t.

  2. “… I want the professional opinion of scientists on how best to limit climate change. They are the ones who understand the problem better than anyone else and quite frankly I don’t trust politicians to understand and communicate the problem let alone dream up possible solutions to it. It would be like getting a diagnosis from your doctor and then visiting your local MP for treatment suggestions. It just doesn’t work that way.”

    I do not fully agree with this. Politicians are the specialists for changing society, scientists are not. In designing a climate change policy you have to compare dissimilar things with each other, scientists can only add up similar things. You have to build coalitions to get policy passed, that is the daily work of politicians, scientists do not do that more than any average person.

    Scientists do have a role in the public debate, the main one is probably making sure that people do not sprout nonsense. That is probably the main reason, why those sprouting nonsense would like scientists to shut up. Scientists can also try to estimate the consequences of certain policy options, but how to add up morbidity, mortality, wealth, changes in power between groups, etc. that is up to society and politicians.

    Scientists are also part of society and thus also have the right to talk about policy. Some are even quite well informed about policy (but not all) and it would be stupid to exclude them and revoke their freedom of speech. But the specialist in this case would be the politician.

    Another thought during the weekend. Do you think you could appify the WG1 report? As alternative to the ClimateGate app. 🙂

    1. I probably largely agree with you here, Victor. I’m not saying that politicians should be absent from the climate change solution discussion. They need to be a big part of it of course, but I do think that scientists, not just climate scientists either, need to be here too. Otherwise we could end up with a situation where say, scientist describes the problem -> politician implements a solution without discussing with scientist whether it will work -> solution doesn’t work. This is essentially what it happening now. We’ve got politicians making feeble attempts at solving the problem but nothing effective has actually happened. Scientists need to be in on this decision making process to make observations about whether the solutions are going to be effective.

      As for appifying the WG1 report, I most certainly could. What are you thinking? The report in it’s entirety in an app?

      1. When it comes to adaptation, the collaboration between politics and science more or less works that way. That is the relatively easy case, with local costs and benefits.

        Mitigation is the difficult part. And the difficulties are mainly political in nature.

        No idea how such an app would like, you are the expert. It would likely be a bit like a book, but lighter to take with you while travelling. You could include a dictionary for the difficult terms. Maybe some of the figures could be customized and e.g. display the situation in your country?

  3. I agree with Victor’s sentiments that it is up to politicians to make societal changes, not scientists. That is what they are there for. The challenge is to elect politicians that are prepared to listen to what the scientists are saying. Most politics is centred around economics as it takes money to do stuff. Unfortunately, the dismal science has many competing ideas about how best to steer an economy and politicians will allow their own ideology to dictate which economists they will allow to advise them. The problem of implementing climate science policy is that the politicians try to apply the same formula and will ignore the overwhelming scientific consensus. If they are allowing their ideology to dictate which climate scientists to listen to they are going to run into a bunch of fringe nutcases or moneytakers. Personally I would like to see more scientists step into politicsand take their critical thinking skills with them.

    1. I’ve had a few thoughts about this and what you and Victor are saying about it being up to politicians to make societal changes. I think you both mean that it’s up to politicians to make and change policy rather than change society. Anyone can change society, right? Bill McKibben is changing society. Philosophers change society and the best example of this is probably Peter Singer. Journalists can change society by exposing corruption; teachers can change society by educating the next generation and so on.

      But in terms of making and changing policy, then yes, that is the job of politicians. And here I agree with you that politicians should be listening to scientists when it comes to making policy that depends on science and it would be nice if they listened to the mainstream view rather than some crackpot outlier.

      It would also be nice to see more scientists in politics but the personality characteristics that draw people to science are quite different to those that draw people to politics.

  4. If politicians represented only their constituents rather than party and it’s affiliations, then perhaps we could trust them. If politicians had dealt with the environment before now, then perhaps we could trust them.

    The world is ruled too much by those who can only talk a good game. The worlds hope is it’s increasing scepticism of the plausibly articulate.

    The only sane policy, with this issue, is get the job done now. The only sane instruction coming from those who know how.

    1. Your last sentence Graham is what I think I’ve been trying to unsuccessfully say. Politicians don’t know how to solve the problem. This is why we need scientists involved in the solutions to this problem and not just the understanding of it. They are the ones who know how to solve it.

      1. You were not unsuccessful. Sometimes it is the listener who fails.

        – – There is currently a problem with connection. My broadband (Talk Talk) works except with WordPress. I’m having to use a dongle (aargh). May not be back for a day or two

      2. I’m not sure they do now how to solve it. Again, scientists know what needs to be done (reduce emissions etc) but when it comes down to implementing appropriate policies that’s where it needs a different type of expertise. On scientists and politicians being different creatures (excuse my paraphrasing of your point) I may be one of the rare ones being an ecologist/plant pathologist who ran as an independent many years ago. I had dreams of winning a seat and having the balance of power and all the bargaining power that comes with it. Alas I secured less than 10% of the vote and went home to lick my wounds 🙂

      3. ukiss, Some scientists have solutions to climate change and I’m thinking James Hansen here. He advocates a carbon tax and nuclear power. He, and other climate scientists can assess things like how much CO2 we can still emit and what solutions will be effective for keeping within that budget. Politicians can’t do that unless they take heed of what the scientists are saying but they’re not. I realise the solution will involve more than just climate scientists though. They will be economists, philosophers, ecologists and probably many others also involved.

        As for running as an independent, why don’t you give it another go? There are lots of examples of politicians becoming successful later in life after earlier defeats.

  5. I’m very surprised that you spammed my comment and video.

    I read that your husband is an academic, although I don’t know which discipline.

    However I’m also surprised that you are prepared to take the IPCC at face value.

    How can a reasonable academic agree that

    “*The warming in the climate system is unequivocal
    *Human influence on the climate system is clear
    *Continued greenhouse gas emissions will lock us into climate changes for centuries to come”

    when there is 1. no Empirical Evidence,
    2. The only real data is some sort of correlation. (When I did Statistics 112 at Canterbury University, the first thing I learnt was that correlations are never proof.)
    3. The IPCC relies almost completely on Computer/mathematical models none of which can do more than illustrate hypothesis’
    4. If you can do, or get hubby to do for you, a least squares regression of data from NOAA you will find that there is no global warming for at least the last 12 years (about the time when it has been technologically possible to measure temperatures accurately)
    5. The IPCC has not successfully explained away the Medieval Warm Period, the Roman Warm Period nor the Holocene Maximum all of which occurred before there was any possibility of anthropogenic CO2.

    6. Finally the remedies suggested by the IPCC and others including the Club of Rome and others will simply kill most of the world’s population including your children and mine. I think that’s an extremely high price to pay for an unproven notion, don’t you?

    Here is the video again.

    I was around during this time, and these guys were absolutely serious. I mean that’s Leonard Nimoy of Star Trek fame narrating. Time magazine did articles and covers and the skiing was great.

    Anyway I understand that comments like this shake your faith and its difficult to shake these things off, even if it is likely to starve you and your children.

    But in spite of that, a good academic should answer such a comment as this with reasoned arguments, pointing to proper evidence and facts to support his views. I would expect no less. All of the above are on my website and more.

    FYI though, I have another site that I post blog pages on when bloggers cannot or refuse to answer my perfectly sane and logical questions and comments. Always with a URL to your blog of course.
    Needless to say, you are welcome to comment there as well because I never delete comments unless they are obscene or obvious spam.

    Anyway I hope you will have the strength to answer genuinely and logically here.



    1. Roger,
      I’ll let this comment stand but all further comments are going through moderation and I’m not going to tolerate any that are not based in fact and science.

      Your video about scientists predicting an ice age in the 1970s is a myth. There were a handful of scientists who wrote papers saying this but the vast majority of papers on the topic were in prediction of global warming. Scientists cannot be held accountable for what journalists at the time chose to write in a magazine.

      Since you like videos, here is a thorough debunking of the 1970s ice age myth:

      I deleted your last posting of the ice age video because I’ve already pointed this myth to people like yourself numerous times and I’m getting tired of doing so.

      And if you’re after proof of climate change without the IPCC and without computer models, then I suggest you watch this video, which provides ample evidence without the need for either.

      And as for your assertion that the IPCC and others will kill off the world’s population. That is completely absurd, alarmist and extreme and possibly also a bit paranoid.

      1. I was going to give a point by point rebuttal to his absurd nonsense but quite frankly I am tired of these people who think that a first semester course in statistics somehow qualifies them to criticise actual experts. If Roger really thinks he knows what he is talking about, he is free to submit a manuscript to a sceintific journal in a relevant field and see how he goes. My guess is he would spout about peer review being corrupt and blah blah blah. It’s moronicand insulting to those of us who actually are working sicentists with peer reviewed publications.

      2. ukiss, I’m glad you didn’t waste your time. The only reason I decided to reply was for the sake of other people reading this who may have found Roger’s comment confusing.

        And Roger, the other reason your first comment got deleted when you made it last week was because you made it three times on three different threads! If that’s not spamming then what is it?

      3. Rachel,
        Oh dear, I see you have not published my earlier comments.
        That really is not friendly at all but thank you for the video which showed the references for that somewhat sensational video you published.
        It was quite difficult to find the reference for the graph at 7.10 on the video because the reference was not complete, but I managed to track it down anyway.
        According to the narrator, it was supposed to be a graph of CO2 and Earth temperatures with solar radiation some how factored in. When I found the reference it turned out that it was a graph of earth temperatures against oxygen isotope 18 used as a proxy. The paper did not elaborate that this was also a proxy of earth temperature at all and in fact the graph on the video was an adaption from another paper and it seems that the CO2 leading the Oxygen isotope was that adoption.
        Equally as misleading was the video narrators assertion that his evidence was computer model free, and that is a good sentiment, but when I read the base paper ie the one where the graph was adapted from-almost the first thing I read is the word ‘computer model’ etc. Just another little detail.

        This is a quite serious case of misleading the viewer, although it is possible that the make of the video didn’t understand the graph either.

        Rachel you must really understand that believing without critical analysis is very dangerous in this IPCC dominated religion. That graph was the key point in the video and it seems to fail any critical review. Sorry.

        Oh by the way, this will all be published on my website at along with your blog with all my comments to date.

        I’m sure as usual there are plenty who will view it and of course you are welcome to comment there too.

        Of course I may be just a little critical of your religious attitude. I hope your academic hubby is more rigorous in his approach.
        But you need to be careful what you publish on the net. I’m sure you are not a liar but you need to be sure of your facts and arguments.



      4. I’ve decided to publish your inflammatory comment, Roger, because you’ve said some things in it that I want to respond to.

        You said, When I found the reference it turned out that it was a graph of earth temperatures against oxygen isotope 18 used as a proxy.

        This is exactly what the key to the graph says it is. If you watch the video again, you will see that directly above the graph it says the red line is the detrended O-18 while the black line is solar radiation + CO2. There is nothing misleading about it. The oxygen-18 isotope is used to measure past temperatures. We don’t have an instrumental record going back further than 150 or so years so we have to rely on proxies. I think it’s very clever that scientists can do this. For a good explanation about how they do it see Paleoclimatology: the Oxygen Balance. A quote from this page:

        Paleoclimatologists use oxygen ratios from water trapped in glaciers as well as the oxygen absorbed in the shells of marine plants and animals to measure past temperatures and rainfall. In polar ice cores, the measurement is relatively simple: less heavy oxygen in the frozen water means that temperatures were cooler.

        Your second assertion that the video is misleading because it says it doesn’t rely on computer models is unjustified. No-where in that paper does it say “computer model”. Perhaps you can point it out to me because I can’t find it. Using proxies to infer past climates does not require a computer model. You are really nit-picking here anyway because Peter Hadfield uses just the one graph from that paper, a graph of CO2 and temperature, for which no computer models were required.

        The rest of your comment is insulting so I’m putting it in the public domain for people to read and judge for themselves.

      5. Yes, you’re probably right. I just couldn’t help myself as I found Roger’s comment so infuriating. The climate change debate is full of people suffering from the Dunning-Kruger effect but how can someone exclude oneself as a sufferer?. That’s a great video.

    1. Thanks, JC Moore. I’ve added your site to my links. I wasn’t sure whether to feel honoured or worried by Roger’s post so I’ve decided just to feel nothing.

  6. Evidence and reason don’t seem to matter much to Roger, so it is pointless to argue with him. Roger didn’t worry me, but a couple of people on is site did, so I quit posting there.

  7. I am not sure who said this. Maybe it was Rachel:
    “Thomas Stoker (sic) (co-chair of IPCC Working Group I) says, “Therefore we conclude limiting climate change requires substantial and sustained reductions in greenhouse gases.”

    Thomas Stocker can be compared to the “Prince of Darkness” because he knows the truth but denies it.

    Prior to becoming a well paid bureaucrat who scorns the Aarhus convention and FoIA laws, Thomas was a distinguished researcher. He was a co-author of some excellent scientific papers including Jouzel et al. (2007) and Luethi et al. (2008).

    These papers show that atmospheric CO2 concentration has been strongly correlated with Antarctic temperatures for the last 800,000 years. This is “Hard Science” in sharp contrast to Michael Mann’s fantasies based on lousy statistical skills, bristlecone pines, a single tree on the Yamal peninsular and the inverted Tiljander sediments.

    Finally, solid proof supporting Arrhenius’ 1896 formula:
    ΔT = “Sensitivity Constant” X {log(base 2) [CO2 concentration in ppm/280]}

    So why does Thomas Stocker “Lawyer Up” when asked about the EPICA dome ice core studies? Here are my speculations:

      1. JC Moore,

        Many thanks for your comment and the interesting link that you provided.

        Arrhenius made elaborate calculations that set A (the climate sensitivity constant = 5.43 K/doubling of [CO2].

        Angstrom pointed out some errors in the Arrhenius’ calculations that would lower the sensitivity constant.

        Moving on the your contention that TSI (Total Solar Irradiance) variations are too small to explain the observed changes in global temperature………….I agree.

        Until my retirement in 2002 I was employed at the Duke University Free Electron Laser Laboratory. One of my ex-colleagues is Nicola Scafetta who contends that solar activity is a major factor affecting global climate. Since the Dalton Minimum (1790-1830) it has been obvious that solar activity measured in terms of sunspots correlates strongly with Earth’s average temperature:
        Scafetta, N. 2013. Discussion on climate oscillations: CMIP5 general
        circulation models versus a semi-empirical harmonic model based on
        astronomical cycles. Earth-Science Reviews 126, 321-357.
        DOI: 10.1016/j.earscirev.2013.08.008.

        Download from here (large file)

        This paper contains a detailed analysis of all CMIP5 models used by the
        IPCC, and demonstrates that they do not reproduce the decadal and
        multidecadal patterns since 1850 (not just the temperature standstill since 2000, the
        failure is nearly total). The paper extensively discusses my astronomical
        based model since the Medieval Warm Period and demonstrates its far better
        performance than the CMIP5 models.

      2. Gallopingcamel, Scafetta’s work is essentially a complicated form of curve fitting. His model has a large number of sinusoidal functions (based on planet orbits, solar cycles, …) which he can then combine to match the observed surface temperature. As a physicist, you probably recognise that one can typically decompose a function into a sum of sinusoidal functions with varying amplitudes. Similarly, one can typically take a set of sinusoidal funtions and combine them with varying amplitudes so as to match almost any function. So, it really has no physical basis and hence, I would argue, does not explain the surface warming in any way whatsoever.

      3. Thanks for the interesting scientific discussion. Scafetta’s work has the empirical shortcomings that the sunspot activity does not show up above the noise in NASA’s temperature record and that the solar insolation reached a maximum in about 1960 and has been declining slightly since.

        It is strange that those who want to attribute all global warming to natural causes, will not accept that the deviations from the models are from natural causes. John Cook addresses that in the video in this article, although I think he overestimates the linearity a bit:

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