How Climate Deniers can “Hide the Incline”

Most of us have seen graphs of global temperature anomaly, like this one using data from NASA:


The temperature increase is, not to put too fine a point on it, obvious.

If we were climate deniers, how could we graph some temperature data that would “hide the incline”? Let’s start by graphing data, not for the whole world, but for a very small piece of it. After all, the variability of temperature in small regions is greater than the variability of global temperature so this will increase the amount of fluctuation and make the trend far less obvious — even if it’s still there.

So let’s pick a record that is well-known and highly reputable: CET, the central England temperature record. It even covers a longer time span than the global estimates! Here’s yearly average temperature (not temperature anomaly) from the CET record:

We’re part way there; the incline is less obvious, but it is still plain to see. In fact the total rise is a bit greater than the global total rise, so if we want to “hide the incline” we’ll have to do better.

How about using less time? To prevent people from thinking we’re cheating (even though that’s exactly what we’re doing), let’s compute seasonal averages rather than annual. The variability in seasonal averages is greater than annual averages so we’ll pump up the fluctuation level even more! But we’ll still have a problem, because for the CET data the autumn season shows even more warming than the annual averages, so despite the greater variability the rise for autumn will still be a bit too obvious:

What next? Let’s stretch out the time axis to make the trend seem more flat. We can do that by graphing, not all the data, but just the last century. I’ll do it like this:

A little better — but the rise is still just too big to be ignored. So let’s stretch things again, or rather shrink things. Instead of plotting the autumn averages from roughly 8 to 13 °C let’s make the y-axis go from about -2 to +18 °C, a range of fully 20 °C, in spite of the fact that the data only cover a range of 5.13 °C.

Now we’re getting somewhere! The rise is still there, of course, but it sure doesn’t look like much.

But how will we justify that axis change? Here’s a great way: plot data for all four seasons on the same graph so it will be crowded and the individual seasons will obscure each others’ detail. That’s why we wanted raw temperature rather than anomaly — so when we put different seasons on the same graph we’ll have to use a y-axis covering 20 °C. We end up with this:

Compare that to the graph of yearly average CET. The fact that CET has risen more than 1 °C no longer stands out, so we’ve managed to “hide the incline” in plain sight. “Mission accomplished.”

If you think this whole approach is just too misleading to be honest, too ridiculous to be used even by the most staunch and/or deluded climate denier, think again. It’s exacty what was done in this post at the WUWT blog.

It seems to be part of Anthony Watts’ attempt to discredit using anomalies in general, in order to discredit a great deal of climate data (which so often uses anomalies). But you don’t really have to use anomalies anyway — look at the graph of annual (rather than seasonal) average CET, which doesn’t use anomalies at all. Perhaps we shouldn’t be too surprised that he so dislikes anomalies; it seems to me that there’s plenty of other evidence he has a serious problem understanding how anomalies really work.


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17 responses to “How Climate Deniers can “Hide the Incline”

  1. If only climate science deniers would show so much creativity studying actual science.

  2. Several comments in an oppositional vein.
    Thanks for the graphs and explanations by the way. Your point is well made.

    The 1880 to 2018 graph NASA is a compilation of different and changing temperature measuring devices, many different and changing sites and one presumes multiple adjustments to the original raw data. Zeke has explained in the past that current NASA etc anomaly graphs have built in TOBS etc adjustments that cool the past.
    Still, if that is what we have that is what we have.

    Secondly the amount of variation given that a yearly annual change can be as large as 0.1C [Guess only] is actually not that impressive over 138 years, or is it not that significant?
    The figures could really be absolute, not anomalies and in Kelvin to give an idea of the real overall change.

    Thirdly they do suggest the presence of the little ice age and presumably there was a fall from previous moderate levels.

    As with all these arguments you might at times have used similar presentations to argue for your points while knowing that a slightly different picture would be available on a bigger/smaller/different graphing scheme?
    Again this is all part of the arguing but if the skeptics, or you, use facile reasoning at times how do we get to the actual truths, such as they are?

    There is a WUWT post on Greenland temps as we speak. Is it possible for you to contrast it’s results with yours or take it down.

    • Angech may wish to consider that the CET is also a hodgepodge of different records and changing instrumentation. For example, between 1723 and 1760 most measurements were taken indoors. Before 1722, there was such poor overlap that a non-instrumental(!) temperature series from Utrecht, in the Netherlands, was used to create a continuous series. At later times, different stations were used to create the CET series.

    • Bullshit. The point is that the warming is real and significant. You ask how we get to the actual truths:
      1) We ignore the idiots at WTFUWT who not only refuse to acknowledge the truth, they refuse to even acknowledge that the truth exists or is important.
      2) We trust the scientific process.
      3) Repeat

    • Well, when I look carefully at each of the seasons, they all show an increase of about 1 degree Celsius over the last 100 years. Which seems pretty impressive to me.
      But of course a casual glance doesn’t show that, because, as Tamino points out, the plot is designed to mislead.

  3. Chris O'Neill

    Another favorite denial technique is to claim that the warming from 1910 to 1945 was “similar” to the recent (since 1974) warming. Therefore all the models are wrong.

    We are dealing with some very deranged people.

  4. Raymond Horstman

    Since there is warming it should make no difference if you take raw data or seasonal data.

  5. Lose the horizontal grid lines on your final chart. The remaining appearance of increase is mainly by contrast with those.

  6. The bare-faced lie presented by Willard (assisted by the ribaldry of his fellow malevolent Howard Goodall) is to suggest that an anomaly is in some was fundamentally different to an absolute value, to the point of its use being dishonest. The lie presented by Watts is easily demonstrated by plotting the two sets of data in the same format (as here – usually 2 clicks to ‘download your attachment’).

  7. good article to show how one can manipulate the presentation and the
    average reader

  8. I’ve once been called a cheater for producing a plot of the Keeling curve with the y-axis not starting at 0, but at 200 or so…. I then argued, that for all practical purposes, 280 would be the real zero line, because it is the long term equilibrium level.

  9. I believe that if we did an analysis using the evolution over time of all GHGs (in CO2 equivalent) vs the global temperature, we would still have a more precise portrait of the causal link between these two parameters. Has anyone ever heard of this type of study?

    • rtremblay,
      The forcings are set out in IPCC AR5 Annex II Table AII.2.1. If you plot out only the CO2 forcing & the anthropogenic aerosol forcing you get a mid-20th century dip that easily matches the global temperature record (as shown here (usually 2 clicks to ‘download your attahment’). If you add in the “GHG Other*” column (*the other gases listed as WMGHG on p1397), the dip becomes flat and if all the other anthropogenic forcings are added, the total continues to rise but at a lower rate in mid-century.
      Of course, to do it properly the volcanic forcings need accounting and to do that you end up in a modelling exercise rather than a graphing exercise which would come out like IPCC AR5 Fig8.18.

  10. It would seem that some have forgotten the example over at DenialDepot:

    http://denialdepot.blogspot.ca/2010/11/how-to-cook-graph-skepticalsciencecom.html

    …or perhaps some thought it was a tutorial.

  11. Thank you; very well done!