A climate scientist tells us that the science is not at all settled

The ABC and the media generally report climate stories as though what they are telling us is the unvarnished truth, and when anyone objects, the response is that the science is settled, or that 97 per cent of scientists agree about global warming. The sceptic or seeker after truth is portrayed as a denier facing the whole of organised science. That’s not the way it really is, at all, but it’s often hard to find, outside the well-known sceptical group, a scientist who offers publicly what I would call a ‘realist’ view. But I came across one the other day, and I thought it would be worthwhile to set out what he says about the so-called settled science of climate.

His name is John Christy. He is Distinguished Professor of Atmospheric Science at the University of Alabama at Huntsville in the USA, and he is also that State’s Climatologist. A third count in his favour is that he is responsible for one of the main temperature datasets that everyone uses, that of the University of Alabama at Huntsville (UAH). Christy has won a number of awards and honours, has testified before Congress, written editorials for the New York Times, and has been an expert reviewer for the IPCC.

The paragraphs that follow, re-ordered by me, seem to me crystal-clear, simply expressed, and most persuasive. He wrote them for a local newspaper in Virginia.

The reason there is so much contention regarding “global warming” is relatively simple to understand: In climate change science we basically cannot prove anything about how the climate will change as a result of adding extra greenhouse gases to the atmosphere.

So we are left to argue about unprovable claims. We can measure and prove that greenhouse gases are increasing. And, in the laboratory, we can measure and prove that adding greenhouse gases to a jar of air will lead to further warming. But when it comes to how the actual climate system might respond to extra greenhouse gases, we’re out of luck in terms of “proof” because the climate’s complexities are innumerable and poorly understood.

Climate science is a murky science. When dealing with temperature variations and trends, we do not have an instrument that tells us how much change is due to humans and how much to Mother Nature. Measuring the temperature change over long time periods is difficult enough, but we do not have a thermometer that says why these changes occur. We cannot appeal to direct evidence for the cause of change, so we argue.

The real climate system is so massively complex we do not have the ability to test global-size theories in a laboratory. Without this ability, we tend to travel all sorts of other avenues to confirm what are essentially our unprovable views about climate. These avenues tend to comfort our souls because we crave certainty over ambiguity.

Christy goes on to dispute that climate models are of much use.

My local supermarket can predict with great skill what I am going to buy, thanks to the information-gathering system now utilized and my boring eating habits. Unfortunately, even the most advanced set of climate-model simulations does not deliver much in the way of certainty.

For example, I analyzed the tropical atmospheric temperature change in 102 of the latest climate-model simulations covering the past 35 years. The temperature of this region is a key target variable because it is tied directly to the response to extra greenhouse gases in models. If greenhouse gases are warming the Earth, this is the first place to look. All 102 model runs overshot the actual temperature change on average by a factor of three. Not only does this tell us we don’t have a good grasp on the way climate varies, but the fact that all simulations overcooked the atmosphere means there is probably a warm bias built into the basic theory — the same theory we’ve been told is “settled science.”

To me, being off by a factor of three doesn’t qualify as “settled.”

Worse, he continues, none of the models has been validated by an independent team. People go on about extreme weather, but Christy points out that the evidence simply doesn’t support the claim that extreme weather is getting worse and that the cause must be carbon dioxide.

So, we argue. Without direct evidence and with poor model predictability, what other avenues are available to us? This is where things get messy because we are humans, and humans tend to select those avenues that confirm their biases. (It seems to me that the less direct evidence there is for a position, the more passion is applied and the more certainty is claimed.)

What about the authority of bodies like scientific academies and the IPCC? Some people, he says, latch onto [such a] self-selected “authority.” Once selected, this “authority” does the thinking for them, not realizing that this “authority” doesn’t have any more direct evidence than they do.

He finishes with a reminder.

Finally, what to do about climate change is not a scientific question; it is a moral question: Is there value in enhancing the quality and length of human life?

If one believes greenhouse gases will cause terrible climate problems, then stopping their release from sources of carbon-burning energy means energy costs will skyrocket. However, the length and quality of human life is directly proportional to the availability of affordable energy, which today is about 85 percent carbon-based. The truth is, carbon emissions will continue to rise no matter what the U.S. does, because most of the world has already answered the real question — that argument is settled.

Should we study new sources of energy? Absolutely. And when they become safe and affordable, they could be ready for deployment. 

Christy’s little essay is one of the best I have read on this subject. Would Professor Flannery, or Professor Steffen, like to provide his own counter?

Join the discussion 15 Comments

  • Peter Kemmis says:

    With his credentials as a climate scientist, illustrated through his roles at the University of Alabama and as the State’s Climatologist, as well as in his service as an expert reviewer for the IPCC, this ‘little essay’ is an interesting adjunct to his recent contribution to the American Physical Society’s review of its position on AGW. Are we beginning to see a little sceptical traction in the mainstream? Is this one of many little kittens setting off to roam among the great flocks of pigeons?

  • DaveW says:

    I read Christy’s essay after seeing the link in Curry’s Week in Review post. He made his points clearly and politely. This often seems to be the way with those scientists labelled ‘skeptics’ or ‘denialists’. Some are quite sharp in their criticisms, but usually refrain from name-calling and bullying. In contrast, the prominent warmest scientists all seem to be cast from the same nasty, vituperative mold. I’ve always found this contrasting approach to the debate interesting.

  • John Morland says:

    Another penny ( hmm.. more like a shilling, perhaps a pound) dropped, another perceptive, pragmatic, precocious passenger boarding a Clitanic life boat whilst the IPCC string quartet is about to play “Nearer my God to Thee”.

  • Mike O'Ceirin says:

    Thanks Don for writing this and it is much appreciated. I have read Christy’s writings for sometime but that essay does put things clearly and it is the first time I have seen it. Those who have a belief system that accepts CAGW as a faith try to discredit him and others as an article of their faith. Name any respected scientist who has turned against the belief in CAGW and I will show you much that seeks to discredit them. For instance http://thinkprogress.org/climate/2014/02/21/3314301/scurvy-wrong-john-christy-climate/ This by Joe Romm seeks merely to discredit Christy. He refers to what others have said is incorrect and makes many associations those suspects such as the flat earth society. Should we ignore CAGW in the same way Lomborg has and instead concentrate on the futility of what is done in it’s name.

  • PeterE says:

    Thanks. This is an excellent and lucid comment that puts the sceptics’ view in a nutshell.

  • Patrick says:

    Another realist scientist working with John Christy is Roy Spencer, an ex NASA prizewinning scientist and team leader of the MODIS system on the Aqua satellite. His site is http://www.drroyspencer.com/ . He has authored a couple of books on”global warming”. You could do a lot worse than add him to your blog roll – jf just for his up to date satellite temp tracking charts with open access to the data. Both have testified to US Gov committees.
    As a sometime physicist I have been very pleasantly surprised to come across this site and appreciate its realistic, down to earth, polite and courteous approach to what seems to be a charlatan, ad hominum dominated field. Now retired, I have spent the last 3-4yrs reading and collecting all I can on the subject but am almost filled with despair that this monster of a ship can be turned around any time soon. Even more so is my, and also of many others, concern for what this is doing to science as a profession with its long and hard fought history of independent and objective thought and its now partisan involvement in policy development. This is especially true of the Royal Society under its last three presidents. I am still searching for some way, however small, to help get this subject back to a rational and objective process.

    • Don Aitkin says:


      I could indeed add Roy Spencer to my blogroll, and I have referred to him approvingly in a number of previous posts. As I understand it, he is retiring from his academic positions, and writing less, but I’ll check on that and make the change if I think it’s a good thing to do.

      • Gus says:

        While having a blog read by one’s old chums is nice, wouldn’t it be better if a person of your standing, Don, had a regular column in The Australian?

        • Don Aitkin says:

          A regular column in the Oz? Happy to have one, and perhaps you could suggest it. The readership of this website seems to mainly Australian, but there are a lot form across the world as well. I knew a few of the commenters, but again most are unknown to me.

  • Gus says:

    Christy is not the only one, of course. If you care to peruse professional literature, you’ll find papers such as doi:10.1007/s11434-012-5619-8 that demonstrates temperatures in Tibet during the Medieval Warming Period to have been higher than today, or doi:10.1016/j.quascirev.2013.10.022 that demonstrates the Arctic to have been ice free in summer in the early Holocene, or doi:10.1016/j.yqres.2014.02.005 that talks about Australia being warmer than today 6000 years ago. Thousands of such papers are published every year, every one of them being an argument against CAGW, written, researched and peer reviewed by climate scientists. The list of authors names alone yields thousands of names of climate scientists who don’t take CAGW for granted or proven or even likely.

    Most ironically though, even IPCC scientists, the miserable gang of 60 harnessed to pull this propaganda wagon, have low opinion of CAGW. The latest AR5 drastically reduces the perceived “threat assessment,” while emphasizing (in deeply hidden corners scattered throughout the document) uncertainty and revising climate sensitivity to greenhouse gases downwards, though, shyly, still not as far as they should have and as observations make clear.

    There’s a good article in WSJ today by Matt Ridley on the latest that has come up from IPCC and that is still going to come and has been leaked already. Who does the leaking, I wonder? Of course, it must be some of the miserable 60, disgruntled with the distortions of their own work that are written in “political summaries” by their scientifically illiterate employers:

    • Mike O'Ceirin says:

      Thanks Gus as you say there is much that disproves “the consensus”. In Canberra Australia we have a skeptics society who to my disgust also accept the CAGW argument when they should at least say there is no certainty. They accept the argument by authority. Why this is so is intriguing in itself. I increasingly think it is an political, propaganda question and constantly addressing the science of it is futile. We should be addressing the cost benefit of the “solutions” since it is deeply flawed. We are trying to sway the “useful idiots” I think. I doubt for the core of the environmental movement it has anything to do with CAGW. They should know that their solutions if implemented to extent wanted will only result mass deaths and a huge reduction in world population. Either that or they totally incompetent as well as barking mad.

      • dlb says:

        The Skeptics Society. They seem like a group whose purpose is to uphold scientific orthodoxy. Any thinking outside the box is just not on. Many of its members disdain religion but treat science with religious fervour. You are right saying they uphold argument by authority.

        I’m very sceptical of any claims made by the Skeptics Society.

    • Don Aitkin says:

      Yes, I’ve read the Ridley article already. Thanks for the other links. There are lots of these papers, and you’ve given three I hadn’t seen. The Arctic paper, however, is model-based and ‘suggests’ rather than ‘demonstrates’. The NIPCC constantly collects the papers that don’t suggest CAGW, so the real question is why the IPCC does not examine them all and provide a balanced assessment — for which we have an obvious answer: it is committed to a CAGW agenda.

      • Gus says:

        “…the real question is why the IPCC does not examine them all and provide a balanced assessment — for which we have an obvious answer: it is committed to a CAGW agenda.”

        Of course, and yet… Every now and then we hear from an IPCC scientist words of sharp criticism of how IPCC cooks its reports, some even withdraw from the game in disgust, others leak. Furthermore, those who have patience to read through the IPCC pages (and Judith Curry does) find that there are often statements in the technical part that contradict what is said in the summary.
        You will often find the same papers discussed in the IPCC reports and in the NIPCC reports, but if a paper contradicts in some way the IPCC lore, it is discussed briefly only, or it is mentioned in the paragraph that talks about uncertainties, or parts of the paper are cited that are least offensive to IPCC editors.
        There is a vast body of climate science literature out there. The body fully reflects–if you bother to follow it–a great variety of opinions on great many topics related to climate. The art of cooking a report, like IPCC report, for example, is in taking from the body what you need only to support your agenda and merely skim over the rest or not mention it at all, if you can get away with it.
        The NIPCC job is in some ways easier: all they need to do is to point to the many papers omitted or under-represented in the IPCC report to demonstrate the IPCC bias and quite effectively demolish their claims and arguments. This, in turn, forces IPCC to improve its game, which is why we have so many statements of moderation and uncertainty scattered throughout the technical parts lately, while the political summary, at the same time, written by hacks and politicos, is ever more assertive while diverging more and more from the technical content.

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