Measuring Climate Sensitivity

As I am sure most of my readers know, most climate models do not reach catastrophic temperature forecasts from CO2 effects alone.  In these models, small to moderate warming by CO2 is multiplied many fold by assumed positive feedbacks in the climate system.  I have done some simple historical analyses that have demonstrated that this assumption of massive positive feedback is not supported historically.

However, many climate alarmists feel they have good evidence of strong positive feedbacks in the climate system.  Roy Spencer has done a good job of simplifying his recent paper on feedback analysis in this article.  He looks at satellite data from past years and concludes:

We see that the data do tend to cluster along an imaginary line, and the slope of that line is 4.5 Watts per sq. meter per deg. C. This would indicate low climate sensitivity, and if applied to future global warming would suggest only about 0.8 deg. C of warming by 2100.

But he then addresses the more interesting issue of reconciling this finding with other past studies of the same phenomenon:

Now, it would be nice if we could just stop here and say we have evidence of an insensitive climate system, and proclaim that global warming won’t be a problem. Unfortunately, for reasons that still remain a little obscure, the experts who do this kind of work claim we must average the data on three-monthly time scales or longer in order to get a meaningful climate sensitivity for the long time scales involved in global warming (many years).

One should always before of a result where the raw data yield one result but averaged data yields another.  Data averaging tends to do funny things to mask physical processes, and this appears to be no exception here.  He creates a model of the process, and finds that such averaging always biases the feedback result higher:

Significantly, note that the feedback parameter line fitted to these data is virtually horizontal, with almost zero slope. Strictly speaking that would represent a borderline-unstable climate system. The same results were found no matter how deep the model ocean was assumed to be, or how frequently or infrequently the radiative forcing (cloud changes) occurred, or what the specified feedback was. What this means is that cloud variability in the climate system always causes temperature changes that "look like" a sensitive climate system, no matter what the true sensitivity is.

In short, each time he plugged low feedback into the model, the data that emerged mimicked that of a high feedback system, with patterns very similar to what researchers have seen in past feedback studies of actual temperature data. 

Interestingly, the pattern is sort of a circular wandering pattern, shown below:Simplemodelradiativeforcing

I will have to think about it a while — I am not sure if it is a real or spurious comparison, but the path followed by his model system is surprisingly close to that in the negative feedback system I modeled in my climate video, that of a ball in the bottom of a bowl given a nudge (about 3 minutes in).

9 thoughts on “Measuring Climate Sensitivity”

  1. Could you explain why you think a creationist would be a good scientist?

    I wonder what Freeman Dyson thinks of scientists who hold beliefs outside of the mainstream?

    Oh wait, I have a quote and a link (I suggest that everyone interested in climate science and public policy read the full [prose] article, not just the following excerpt):

    In the modern world, science and society often interact in a perverse way. We live in a technological society, and technology causes political problems. The politicians and the public expect science to provide answers to the problems. Scientific experts are paid and encouraged to provide answers. The public does not have much use for a scientist who says, “Sorry, but we don’t know”. The public prefers to listen to scientists who give confident answers to questions and make confident predictions of what will happen as a result of human activities. So it happens that the experts who talk publicly about politically contentious questions tend to speak more clearly than they think. They make confident predictions about the future, and end up believing their own predictions. Their predictions become dogmas which they do not question. The public is led to believe that the fashionable scientific dogmas are true, and it may sometimes happen that they are wrong. That is why heretics who question the dogmas are needed. [emphasis added]

  2. Sir Isaac Newton was a creationist. Do we thereby dismiss the laws of motion, the refraction of light, or calculus?

    This is what is known as an ad hominem argument; arguing from the characteristics of the arguer rather than the content of the argument itself. It’s a well-known logical fallacy. And whatever you might say about a creationist, someone who accepts ad hominem arguments as a basis for making scientific judgements is quite definitely not a good scientist.

    I have no more problem with declaring Roy Spencer wrong on ID than I do on declaring James Hanson wrong on catastrophic warming (and right on ID). Only people who rely on authority would think this argument could have any weight.

  3. No, this is not an ad hominem argument, unless you sincerely believe that pointing out flaws in someone’s intellectual ability is a dirty below-the-belt trick, and we have to treat all scientists as intellectually equal. Would describing someone as likely to be a poor high-jumper because they are four feet tall be an ad hominem attack?

    Who is ‘James Hanson’ and why do you declare him wrong? More importantly as far as this thread goes, do you declare Roy Spencer right? Do you think scientists generally are in agreement with your ‘declarations’?

  4. Fascinating paper. I would like to know the following:
    Figures 5 and 9, the actual radiation/temperature data for the real world, show strings of almost connected points which suggest trajectories along the proposed feedback lines. The figure comment suggests 91 day averages, but this would be far fewer points than are shown. What exactly is the time-average of each point?
    Are the adjacent points along these lines adjacent in time as well?
    If so, it would be nice to add arrows representing the flow of time, and numbers that can be cross-referenced to a global temperature/time graph, so the various events such as el-nino and Pinatubo can be identified.
    If the 8W/degC lines represent semi-stable states of the Earth’s climate, with changes to a new semi-stable state occurring intermittently, then, to disprove GHG-induced global warming, it would be necessary to show that the positions of these semi-stable states is not affected by GHG (from extra CO2).

  5. Looks like the person who likes to play around posting with the names of others has hit all of the threads.

    This post:
    Posted by: Vince | August 26, 2008 at 12:42 PM was not me.

  6. “That is why heretics who question the dogmas are needed”

    Indeed, but what is religion if not dogma? What are heretics, if not those who question or reject religion?

    Dyson states he is a humanist. Humanists are atheists.

    Newton lived in a time when literally EVERYONE was religious. It was pumped into your brain from the day you were born. You couldn’t NOT be religious, at least not openly: atheists were indeed branded heretics and persecuted. No-one even considered the possibility of god not existing back then, it was taken as read, no-one questioned it.

    And no, we shouldn’t reject Newton’s findings, because they have been reproduced thousands of times over hundreds of years by hundreds of scientists. Also, Newton’s religious views had no impact on that area of his science. He also researched occults studies, alchemy and the apocalypse

    But in today’s society, when people are open to the idea of the non-existance of God, it is frankly embarrassing for a scientist to proclaim a disbelief in truly settled science, based on stories written in a 2,000 year old book.

    It doesn’t make Spencer’s findings incorrect, but it casts some doubt on his scientific credentials (as it does on Newton’s other areas of work), unless these results can be reliably re-produced by some other, independent parties.

    Sorry for the rant

  7. it casts some doubt on his scientific credentials

    No it doesn’t. Only contrary scientific research can cast doubt on his scientific research.

    It is sad how many global warming alarmists there are who can’t rebut someone’s science, so instead they engage in ad hominem attacks. It has gotten to the point where they think such an attack demonstrates anything but their own ignorance.

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