Q: Why are there no intra-annual patterns in global temperature anomalies?

A: because they are anomalies.

Climate sceptics want to be taken seriously. They want to hold joint conferences with climate scientists. It is not impossible for climate sceptics to do good research, though whether the odds are better than a monkey typing Hamlet is unclear on the evidence below.

A few weeks ago, Willis Eschenbach posted some CERES total solar irradiance (TSI) data at WUWT that showed that TSI varies from about 330 to 350 W m-2 over the course of a year. Eschenbach wondered why this >20 W m-2 difference was not obvious in the global temperature record.

… where is the effect of the ~ 22 W/m2 annual variation in the amount of sun hitting the earth?

He has some ideas. But not good ones.

To get an idea of the predicted effect of this variation in TSI, using IPCC figures this TSI change of 22 W/m2 is about the same change in forcing that we would get from six doublings of CO2 … that is to say, CO2 going from the current level (400 ppmv) to the extraordinary level of 25,600 ppmv.

In addition, again according to the IPCC, using their central value of 3°C warming per doubling of CO2 (3.7 W/m2 additional forcing), this change in forcing should be accompanied by a change in temperature of no less than 18°C (32°F).

Now, I can accept that this would be somewhat reduced because of the thermal lag of the climate system. But the transient (immediate) climate response to increased forcing is said to be on the order of 2°C per doubling of CO2. So this still should result in a warming of 12°C (22°F) … and we see nothing of the sort.

One would have hoped that Eschenbach had been interested in climate change long enough to remember some of the basic definitions. The transient climate response is not an immediate response. It is defined by the IPCC as.

… the change in the global surface temperature, averaged over a 20-year period, centred at the time of atmospheric carbon dioxide doubling, that is, at year 70 in a 1% yr–1 compound carbon dioxide increase experiment with a global coupled climate model.

The Earth’s climate will no more show an immediate 12°C response to the intra-annual variability in TSI than a kettle will instantly boil when plugged in. The climate system has an enormous thermal inertia, mainly in the oceans.

But shouldn’t there be some response to this variability in TSI? Yes, but the global temperature anomaly is an anomaly. For each January, the mean of the climate normal period (often 1961-1990) for January is subtracted. Ditto for February and the other months. This processing removes any tendency for Januaries to be warmer or colder than Julys. Eschenbach won’t find the pattern he is looking for because he is looking at the wrong data and he really ought to know this.

But what if he looked in the right place – the variability in absolute temperature as discussed by Jones et al (1999)

The annual cycle of global mean temperatures follows that of the land-dominated NH, with a maximum in July of 15.9°C and a minimum in January of 12.2°C.

Perihelion, the Earth’s closest approach to the Sun, currently occurs in early January. This timing probably mutes the annual cycle in global mean temperature by offsetting some of the hemispheric differences.

Not to be out done, Stan Robertson takes up Eschenbach’s theme without realising that it is nonsense.

… why don’t we see some significant annual cyclic variation of global mean temperature? This is a truly profound question! It ought to keep climate modelers awake all night, every night.

Yawn.

We do need a better class of climate sceptics.

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About richard telford

Ecologist with interests in quantitative methods and palaeoenvironments
This entry was posted in Silliness, WUWT and tagged , . Bookmark the permalink.

22 Responses to Q: Why are there no intra-annual patterns in global temperature anomalies?

  1. Good post. I didn’t read all of Willis’s post, but my immediate thought was “but, they’re anomalies”.

    We do need a better class of climate sceptics.

    Either you’re copying me, or great minds think alike? 🙂

  2. FWIW, there seems to be some disagreement over whether you’re right (as in, its all anomalies). See http://blog.hotwhopper.com/2014/11/someone-needs-to-explain-seasons-to.html where Sou thinks your comment may not apply to WE’s post. My suspicion is that you are right. In which case (as I said there) WE and WUWT are even stupider than we thought. But bits of the Light Side are missing stuff too.

    • You’ve made me read it now. It’s possible that they haven’t been confused by temperature anomalies and are simply arguing that the annual variation solar forcing should produce a larger variation in temperature than is observed. As Richard points out, though, we wouldn’t expect to be able to respond that rapidly to such variations in forcing and hemispheric differences (more ocean in the SH when the Earth is closer to the Sun) presumably also contribute.

      • Timescales was my original thought (and its weird that they didn’t think that, because its easy to put into “electrical engineer” signal-processing filter-response language, which they usually like: the climate system is like a low-pass filter. Indeed, isn’t this effectively the classic Hasselman 1976 (http://onlinelibrary.wiley.com/doi/10.1111/j.2153-3490.1976.tb00696.x/pdf) red-noise-climate as integration of white weather noise?) If that is the answer, then I still think Sou’s post is “wrong” as spends far too long saying that.
        However, it would be far more fun if RT is right – and that would depend on what temperature dataset WE is using.

      • I’ve gone and read them again. In the more recent post by Stan Robertson it says

        First, why don’t we see some significant annual cyclic variation of global mean temperature?

        As far as I’m aware, we do, unless by significant he means even more than this. If he means that we don’t really see anything much, then that might suggest he’s been looking at anomalies as Richard suggests. Who knows and they’ll almost certainly never admit it if they were (well, unless they are even more stupider than it currently seems).

    • Stan Robertson is unambiguously using anomalies:

      “one might expect to see a fairly substantial annual cyclic variation in global mean temperature. I failed to recall any in the many plots of global temperature anomalies that I have seen”

      and goes on to run a spectral analysis on HadSST.

      It is less clear which temperature Willis Eschenbach is thinking about. It is possibly that the stupidity I’ve ascribed to Willis with respect to anomalies belongs to Stan alone. But if Willis knew that the January-July difference was 3.7°C, I would have expected him to refer to this to give some context.

  3. There’s a more explicit admission of error in this comment. I’d withhold the kudos, though, until the post itself gets a prominent note saying “this is all crap”. At the moment, you have to scroll into the comments.

  4. verbascose says:

    Just for the record, here’s a comment from Stan Robertson from which it gets clear that he is indeed “bones”:
    http://wattsupwiththat.com/2014/07/26/solar-cycle-driven-ocean-temperature-variations/#comment-1694832
    One can safely exclude him as candidate for the “class of better climate sceptics”.

  5. Pingback: Oh, lordy! – Stoat

  6. Eli Rabett says:

    The past repeats itself mirthfully. McKitrick made the same error, except he DIDN’T use anomalies and then claimed that the annual variation was proof that there was no such thing as global temperature.

  7. Eric Steig says:

    “We do need a better class of climate skeptics.”
    There IS a better class of skeptics. We are called scientists.

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