The Hunt for Global Warming: Southern Africa Part 2

This post follows on from Part 1 where a discussion about urban heating was left unresolved in the comments.

  • Flicking through many southern African temperature records I have observed two main trends. One is mainly flat, the other is clearly warming. I believed that rural records (towns with <10,000 inhabitants) displayed flat trends while urban records may be flat OR show warming. The theory I want to test in this post is that all warming in southern Africa is linked to urban heating.
  • Warming records and flat records are geographically mixed (Figure 1). Southern Africa is either warming, which means that all the flat records are wrong, or it is not warming which means all the warming records are spurious.
  • Lourenco Marques in Mozambique has a population of 755,000 and shows a clear warming trend. I placed Lourenco Marques at the centre of a NASA GISS search that returned 33 records (GHCN V2 unadjusted). ALL 16 rural records are plotted together with 7 urban records that show flat trends. Ten urban records that show clear warming are treated separately.
  • The 23 rural + urban record group displays a flat to cooling trend. The 10 urban group displays clear warming of about 1˚C per century. It seems quite clear cut that the perception of warming in this part of southern Africa is down to urban heating that may be linked to deforestation, land use change, residual heat from energy consumption and badly sited thermometers. But not all urban sites are affected, for example Pretoria University does not display warming while Pretoria does.
  • There are very serious issues with data structure. There are a great number of rural records that span 1960 to 1990. NONE extend beyond that. And there is only a single “flat” urban station that remained open beyond 1990 and that record is suspect (Durban, see part 1). Therefore, to define temperature since 1990 it would be necessary to use urban records known to be affected by urban heat. It seems odd that all of the urban stations displaying flat trends were closed.
  • I would strongly advocate that urban records shown to be affected by urban heating SHOULD NOT be used in temperature reconstructions. And yet it seems that this is exactly what all of the main groups (GISS, NCDC, Hadcrut, and BEST) have done.

Figure 1 33 Stations used in this post centred on Lourenco Marques in Mozambique. In yellow (white text) are the 10 urban records that show warming. In red, the 16 rural + 7 urban stations that show no warming.

Figure 2 List from the NASA GISS web platform showing the 33 stations within 672 km of Lourenco Marques together with the populations. Data are GHCN V2 records from this NASA GISS source.

Figure 3 Temperature spaghetti plot for the 23 flat rural and urban records. Note how all bar one of these records stop around 1990. Only Durban, that has dubious quality, can be used from this group to define temperature trend 1990 – 2011. There is a similar problem with older records. It is only from 1917 that there is more than one record. Note the high density of records 1960-1990.

Figure 4 Temperature spaghetti plot for the 10 urban records that show clear warming trends. The populations are listed below:

  1. Lourenco Marques 755,000
  2. Volksrust 15,000
  3. Pietersburg 27,000
  4. Estcourt 15,000
  5. Jan Smuts 1,417,000
  6. Pretoria 573,000
  7. Johannesburg 1,417,000
  8. Vereeniging 250,000
  9. Bethlehem Air 30,000
  10. Rustenburg 35,000

Figure 5 Temperature anomalies (dT) are calculated for each of the 23 stations (Figure 3) using the average temperature for that station as a reference value. The average dT is then calculated for the stack. There is clearly little sign of warming. But beware. There is only a single record (Durban) pre-1917 and a single record (Durban) post 1991.

Figure 6 Same as Figure 5 but the time axis is chopped at 1917 and 1990 to remove the single record part of the stack and a 5 year centred running mean run through the data to reveal the structure. There is a temperature top in 1984 but the overall trend is slowly cooling, and these data, that are regarded as the most reliable, cannot be used to define the time – temperature trend since 1991.

Figure 7 Equivalent to Figure 5 for the 10 urban stations that show clear signs of urban heating.

Figure 7 Equivalent to Figure 6 for the 10 urban stations that show clear signs of urban heating. About 1˚C warming per century is evident. Note that in this part of Africa, it is only these stations, evidently affected by urban heating, that provide evidence for regional warming.


In southern Africa there is a serious issue with station closures that looks like it may have been selective. ALL rural stations that show no evidence of warming have been closed. All urban stations that showed no signs of warming bar one have been closed. Only urban stations that show signs of man made urban heating have been kept open and these stations should not be used in temperature reconstructions. This means there is no reliable record of temperature change in this part of southern Africa since 1990. What to do?

In order to get long records and recent records in southern Africa it is necessary to use urban records. This analysis shows that urban records that are warming are almost certainly affected by urban heat and need to be avoided. Hence, only long urban records that show no sign of warming have to be used. Imperfect I know. The keepers of the records have a lot to answer for.

Homogenisation of raw data may account for a small amount of spurious warming in southern Africa. Selectively using urban stations affected by urban heating accounts for a lot more.

Figure 8 The temperature anomaly stack for 26 widely spaced stations (urban and rural) presented in Part 1 are probably the most reliable representation of temperature – time in this part of southern Africa.

Figure 9 In the comments to Part 1 of this post, Roger Andrews produced this nice graphic that basically shows the same temperature trend as Figure 8 above and the regional distribution of long urban records that show no sign of regional warming.

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21 Responses to The Hunt for Global Warming: Southern Africa Part 2

  1. concernclub says:

    so yes, not everyone who tries to average global temperatures is doing it correctly
    but what does it demonstrate about the physics principles of greenhouse gases?

    Perhaps more acceptable and interesting to monitor is the arctic sea ice coverage
    (who wants to make a bet for the 2015 minimum in September 2015?)

    I bet the minimum will be less than 4.5 million km2 and would not be surprised if it will become
    the new record low (thus I expect more 3.5+-0.5 million km2 or less than 4.5 with 95% probability). In any case far below (or 10-15 years earlier than!) the IPCC climate models predicting such a minimum.

    From the diagram here one gets the IPCC bet for such low numbers around 2030+-5 years or so. For example here:
    (full information here

    • A C Osborn says:

      No it is much more interesting to look at Antarctic record breaking Sea Ice and Northern Hemisphere record breaking Snow and Low Temperatures.
      Not forgetting of course World Record Breaking one day snowfall.
      But of course you will not see any of that in the MSM or NASA Public Statements will you.

      • concernclub says:

        yes antarctic is also interesting..
        but lets do a bet!
        lots of predictions that ice age is coming.
        What do you risk?

        • A C Osborn says:

          I would bet everything I own that there is going to be an Ice Age.
          The only real question of course is the timing.
          As I only bet on sure things that are based on facts I would not even try to hazard a guess as to the timing.
          But are you prepared to bet anything on where the Satellite Temperatures are going to go over the next year?

          • concernclub says:

            satellite data in 2015 (end of)
            well, I bet
            about 0.15+-0.05 C warmer when compared to
            the average from 1995-2005.
            so lets say 0.1 degree warmer than the average is my bet. (if you have the average already?)

            what is your bet?

          • A C Osborn says:

            So are you suggesting that the UAH Satellite temperature will be about 0.10 to 0.15 Colder than it is currently?
            If so then I would probably agree with you, although I am not sure if you mean that as the average for 2015 or not.

          • concernclub says:

            if not clear the average from the past 10 years
            so 2015 will be warmer than 2000-2010 average
            (but 1995-2005 would also be fine as you prefer)
            by the amount I wrote.

            with large annual fluctuation similar to the predicted average increase every 10 years.

    • manicbeancounter says:

      Arctic sea ice extent provides no test at all about the extent of the GHG effect as
      a) We know there was warming in the early twentieth century when the GHG effect was small, but no records of the sea ice levels.
      b) Lows could be caused (as in 2012) by storms, or longer term changes could be caused by changes in ocean current.
      c) Evidence is that there was a cold period just prior to the satellite data starting.
      For all these reasons 35 years of sea ice data are a very poor proxy for global temperatures. We can only do a proper test of the GHG effect one we have a reliable temperature data set. The increasing evidence from Euan Mearns is that the natural (or random fluctuations) has been smoothed out by homogenisations, but that the adjustments for urban effects have not been made. Due to the nature of these factors we can only assume that the empirical magnitude of any GHG effect estimated from current temperature data must be overstated. To assess the impact, a rigorous reappraisal of the data must be undertaken.

  2. Javier says:

    We do have the capability to properly adjust those post-1990 records for UHI effect, it just has to be done correctly. Plus we have satellite data for the entire region, not subject to UHI effect, so it should not be a big problem.

    The closure of stations could be due to budgetary constrains. Big cities would be the last places where cuts require closure, as stations in big cities are often associated to research institutions.

    The important finding is that we do have lots of data for most of the period of highest warming in the 20th century, 1975-1998, and that data shows very little warming in South Africa. This does not bode well for CO2 being the main driver of global warming, since CO2 is global but the warming is not.

    • Euan Mearns says:

      The important finding is that we do have lots of data for most of the period of highest warming in the 20th century, 1975-1998, and that data shows very little warming in South Africa.

      And central Australia. And I’ve looked at enough records from S America to see same. Roger has already done a large compilation. His turns up a bit at the end because of inclusion of more urban records.

      I’m actually astonished by this which is why I’m spending so much time pursuing this on a regional basis. I’ve never seen a region-wise breakdown of warming done like this before. It will be a bit odd if Global warming is not global.

      • Javier says:

        Based on what I have read, you are likely to find the same situation in Sea Surface Temperatures. Apparently some regions of the oceans, like Northern Pacific have warmed very little or have actually cooled, while others like the North Atlantic have warmed more.

        It seems global warming is not global at all. Warming seems to be quite selective, affecting not only different land and ocean regions, but also raising minimal temperatures, specially during the winter and at night without affecting much summer and day temperatures. I suppose that the models are at odds to explain all this variability.

        My personal opinion is not worth much, but it seems to me that the heat enters the Earth mainly at the equatorial pacific ocean region, where it charges the ENSO and it then gets distributed according to a multidecadal pattern towards the AMO. Once in the North Atlantic, the “cul de sac” disposition of land masses makes for an efficient transfer from sea surface to land surface. The hypersensitive enclosed Arctic region is the last in the chain, and if it doesn’t get enough heat… there goes the glacial period. Sun, cosmic rays and clouds are the main regulators of the amount of heat that this distribution system carries with the occasional volcano thrown in.

        Judith Curry has a model of this distributor in a paper on the Stadium Wave proposal (Wyatt & Curry 2013), but she doesn’t deal with many of the differences that we are discussing and she is also not the first one to deal with this oceanic distribution. In this type of distribution you would expect that a period of warming (1975-1998) would result in heat accumulated at the end of the chain (Northern Hemisphere land), while a period of no warming (1998-2030) should see a more homogeneous global temperature behaviour. I think that this could explain a lot of what Roger and you are seeing.

        The effect of CO2 can explain shorter winters and higher minima.

        Just an hypothesis of course. This stuff is awfully complicated.

        Wyatt & Curry 2013 Role for Eurasian Arctic shelf sea ice in a secularly varying hemispheric climate signal during the 20th century.

  3. A C Osborn says:

    Euan, 2 things, first and most important, I do not think that most of those stations have been “closed”, they have just been removed from the GHCN database. You would need to check if there are any more actual records before you can say whether they are closed or not.
    Second, the classification of “Rural” being less than 10,000 population is arbitrary and according to Roy Spencer wrong.
    Have you actually read his very comprehensive study on UHI?

  4. A C Osborn says:

    Even more confirmation of data changing

    The second chart says it all about the changes from 2014 to 2015 data.
    And this is Science?

    • concernclub says:

      Perhaps you could explain what you mean by:

      “science”, “scientist”,

      and as you probably need to make use of the “scientific method”
      you can distinguish between “established” scientific facts and
      “new science in the making”.

      And all this in contrast to “pseudo science”
      (obviously a title obtained at a university does not guarantee that this person
      acts according to the scientific method.)

      • A C Osborn says:

        So are you prepared to condone adjusting data that has already been adjusted as “Science” or “Scientific”?
        A simple yes or no will do.

        • concernclub says:

          adjusting data is always dangerous for “science”
          leaving out data which are important is also dangerous
          for the value of the result.
          One always needs to explain what is being done in principle.

          so yes, science (in the making!) and the scientific method demands to formulate hypothesis.

          concerning the co2 problem the modelling predictions say
          +0.15+-0.05 C every decade and this is well confirmed
          from different measurements so far.

          the models also predict more warming in the northern
          high latitudes and this is also confirmed.

          the models fail on other things ..

          like the arctic ice melting minimum

          alternative models make different hypothesis
          to be tested.

          the sun spot model failed badly

          the new ice age model for the arctic (or oscillation model)
          as well.

          so lets take all data and make new and better hypothesis
          (and explain well why some “averaging” by the IPCC people
          is wrong)

          fine with me. But, look at all the data!

          so lets do the bet for the arctic ice minimum!

  5. Luís says:

    Hi Euan, a few notes:

    Lourenço Marques was the name of a Portuguese nobleman that was sent to explore the Espiríto Santo estuary in the XVI century. The Portuguese established a trade post in the north bank of the estuary that took the name of this explorer. The trade post was destroyed various times by the natives (and possibly the Dutch) until a fortress was built by the late XVIII century.

    Lourenço Marques started developing as city only by 1875, when a mission was sent by the Portuguese crown to plant gum trees, build the very first hospital and the very first church. Roads where soon open to South Africa and in just 25 years it became the capital of the Mozambique colony. This is sort of an industrial age city, its temperature record is thus more relevant than others.

    Mozambique became an independent country in 1974, after the Carnation revolution in Portugal, that put an end to a decade of independence war. The city was renamed Maputo by the new Mozambican authorities. The usage of Laurenço Marques is today perceived as nostalgia for colonialism and fascism. I am somewhat startled to see this outdated toponym being used by GISS.

    Maputo is home today to some 1.7 M folk, just 1 M more than what is reported by the GISS. Also note that the coordinates given – 25.9º S 32.6 E – seem to coincide with Maputo’s airport.


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