Australia is not getting warmer. It is getting less cold !

Maximum temperatures in Australia are on average not increasing at all. Instead an increase in minimum temperatures explains the ~1C warming observed since 1910.

All these results are from ACORN-SAT which have already been adjusted and homogenised.  They are the same as those used by GHCN and CRUTEM. What the data really shows is that night time temperatures across Australia have increased, while daytime temperatures have hardly changed.

To check my results simple download the daily minimum and maximum temperatures from all 112 stations that form ACORN-SAT.  Then spatially average all annual maxima and minima temperatures.



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17 Responses to Australia is not getting warmer. It is getting less cold !

  1. Jerry says:

    It seems critically important to understand the mechanism(s) responsible for the higher lows versus higher highs. In your last blog you touched on this but it still did not seem definitive. Gut feels says there is something there that we need to understand. If CO2 ain’t it then it would be great to understand what “it” is.

    • Clive Best says:


      CO2 is playing a role. However all global temperature temperature studies average out seasonal variation and diurnal variation, As a result it appears that all temperatures are increasing uniformally. This isn’t true – it is just anomalies that increase and these are always calculated relative to seasonal norms. These seasonal norms are based on the offset of monthly average temperatures calculate by (tmax-tmin)/2 from the seasonal norms. As a result all information on trends in tmax and tmin are hidden. I am just bringing these individual trends out into view.

      Clearly it would be worse if maximum temperatures were increasing faster than minimum temperatures. However, this is not the case.

  2. Euan Mearns says:

    Clive, 2 very important charts IMO. Chart 2, plateau 1910 to 1950; plateau 1970 to present. T night rise 1950 to 1970 = green revolution. More water vapour in the atmosphere supporting night time temperatures. More transpiration and irrigation? Check out regional patterns. E

  3. paulski0 says:

    What the data really shows is that night time temperatures across Australia have increased, while daytime temperatures have hardly changed.

    That’s not what you’re showing. To test how “daytime temperatures” have changed you would average all daily Tmax readings. What you’re doing instead is showing only the single highest recorded datapoint from each year (1 sample versus 365) – that’s about extremes, not daytime temperatures in general.

    Daytime temperatures in Australia have warmed according to all the major datasets.

    As covered in the previous posting there are some fairly simple reasons why extremes as recorded might spuriously show the pattern observed, even after homogenisation.

  4. erl happ says:

    Night time temperatures are increasing? The simplest answer is worth considering.

    The temperature of the air is governed by where it comes from. Low latitudes are warm. High latitudes are very cold. There is a variable rate of transfer of warmth from low to high latitudes.primarily governed by the differential between surface atmospheric pressure between the trough on the margins of Antarctica and surface pressure across the rest of the globe.

    Surface atmospheric pressure on the margins of Antarctica has been in free fall for seventy years.

    Surface atmospheric pressure on the margins of Antarctica is a product of polar cyclone activity generated by the difference in atmospheric density in parcels of air that occupy the vertical space between 400 hPa (7000 metres) and 50 hPa (20,000 metres). In terms of atmospheric depth that’s about half of the total. It is in this region that the strongest winds are to be found..

    The extreme differences in atmospheric density across the polar front are in part due to the convergence of warmer air of tropical origin and colder air descending from the mesosphere inside the polar front. Remember, Antarctica has the highest surface pressure on the planet in winter. The trough on its margins exhibits by far the lowest surface pressure experienced on the planet all year round.

    A strong contributor to the variable amount of warmth of the air travelling from the mid to high latitudes is the warmth derived from ozone as it absorbs long wave infrared emanating from the planet itself, an inexhaustible source of energy for the heating of air containing a molecule capable of absorbing that energy. Unlike carbon dioxide ozone is not uniformly distributed within the atmosphere.It is safe from photolysis by short wave energy from the sun at low altitudes and high latitudes, especially in winter.

    It is ozone that is responsible for the positive lapse rate in the stratosphere. Its not heating by short wave radiation that is responsible for the reverse of the lapse rate (above the tropopause) but heating by the Earth’s long wave infrared as it is absorbed by ozone. Unfortunately, this easily demonstrated reality is as yet unknown to ‘science’. See

  5. Ron Clutz says:

    I found a similar pattern looking at hemispheric maxes and mins in BEST dataset. I wanted to test an assertion from Chiefio:
    “I’d actually assert that there are only two measurements needed to show the existence or absence of global warming. Highs in the hottest month must get hotter and lows in the coldest month must get warmer. BOTH must happen, and no other months matter as they are just transitional.”
    Sure enough, highs are not getting higher, but lows are less low.

  6. Ron Graf says:

    The established explanation for what is going on in Australia seems to be that there is a large “oasis effect” with irrigation and agriculture expansion. This is sometimes called reverse UHI. But although oasis effect cools the daytime high through evapo-transpiration it also warms the nights by back-radiation caused by the increased vapor levels.

    The Urban ‘Oasis’: High Resolution Landsat 5TM and ASTER Thermal Imagery Shows the Influence of Water Usage on City-Wide Temperatures in Dubbo, Australia

    So we need to find Australian cites that have not grown in population or agriculture. Or, we can find new automatic weather stations that are in these locations and use them in pairwise comparison to sites with UHI and reverse UHI. When I say “we” I mean if Clive — that is if he keeps up his interesting line of investigation.

  7. Nick Stokes says:

    Your results don’t look at all like to BoM results (source) for average daily max and min, which definitely show maxima strongly increasing:

    I think you need to make quite clear that you are talking about the average of each stations max for the year, not for the day. How to get a sensible spatial average for that is quite a question, but just averaging the absolute temperatures that report in any one year won’t do. There are plenty of places with quite a lot of summer data missing.

    • Clive Best says:


      I have calculated monthly minimum and maximum temperature anomalies averaged each year. I get a very similar result to BOM !


      So on the surface it looks like this contradicts what I wrote above. Maximum temperature anomalies are rising, although only significantly after 2000. However, the two measurements are different.

      When you calculate anomalies you first must average daily minimum/maximum temperatures for each month over a 30 year period 1961-1990. Then as a second step subtract the average monthly min/max temperature from 1910 to 2017 from these 12 normals, and finally as a third step average together the 12 monthly anomalies for each year.

      What I did above was different. For each station I found the highest and lowest recorded temperature in each year (and month). So the annual value is the extreme low and high temperature recorded that year for each station. I then then make the spatial average over Australia. A year with extreme heat in Australia therefore should have a high average Tmax value. Likewise an extreme cold year should have a low average Tmin value.

      What I think this shows is that extreme cold years are getting warmer, whereas extreme hot years are not.

      • paulski0 says:


        I don’t think the difference has much to do with anomalisation. It’s mainly that the standard Tmax average datasets sample every day in the year whereas you only sample one day in the year – the most extreme day.

        As a little test I wonder what you’d see if you did the same thing but using only, say, the 30th warmest day at each station rather than the 1st warmest.

      • Nick Stokes says:

        My issue is mainly that you don’t use anomalies, and it would be rather hard to do so. That leaves you vulnerable to missing data. If earlier years had more hot places reporting than later (there are missing periods) then that shift in normals can easily outweigh a shift in the anomaly component.

        A variant of this is that quite a lot of places have several missing days even in years when they are reporting. This doesn’t matter if you are averaging all days, but for an extreme, you only need to be missing that day to make a radical difference.

        • Clive Best says:


          Yes I know. But if you use anomalies then everyone gets the same result, because they are locked into working only with monthly averages. You can then miss any subtle changes in temporal temperature distribution or UHI effects. The spatial average of normalised temperatures is really just averaging over the deltas. So it is more like measuring distance travelled based on averaging small changes in velocity.

          A good example of this is enhanced Arctic Warming. We say the Arctic is warming twice as fast as say Spain, but in reality increasing temp from -45C to -43C is quite different from increasing temp from 35C to 36C. The heat flux needed is different.

          Yes there is a missing data problem but the spatial averaging should partially overcome that. Since there is less data early on in the record you would expect the maximum recorded temperatures to increase, simply due to better daily coverage. However, we don’t even see this. Record high temperatures are remarkably stable.

  8. phil chapman says:

    It is not surprising that warming in Australia means higher minimum temperatures. Global warming in general does not mean a uniform increase in temperatures everywhere but warmer winters in areas now cold. All models indicate that the principal effect is a reduction in the average equator-to-pole gradient.

    At the Early Eocene Climatic Optimum, 52 Mya (million years ago), the atmospheric CO2 was somewhere between 2000 and 4000 ppmV (vs 400 ppmV now) and the average global temperature was at least 15 C higher than now – but what this meant was that the tropics were relatively unaffected while there were palm trees and cold-blooded reptiles in the Arctic.

    The truth is that the Hothouse Earth is the normal climate. Since life emerged from the sea, there has been only one episode (during the Carboniferous Period, 300 Mya) when the poles had icecaps and the average global temperature and atmospheric CO2 were as low as they have been during the Pleistocene (the last 2.6 million years). We are living in an ice age, and a CO2 desert.

    Of course a return to normal Hothouse conditions would require adaptation in human societies, and some species that could not migrate or adapt would become extinct, but it is absurd to argue that such a world would be somehow disastrous. There is no doubt at all that it would be a lush world, much more benign than the one we have.

    In reality, however, the issue may be moot, because the Hothouse (anthropogenic or natural) may be delayed. It is quite likely that within a decade or two the current Eddy Grand Solar Minimum will allow people to walk across the sea-ice from Manhattan to Staten Island, or to ice-skate on the Thames, as they could in 1700, during the Maunder Minimum. (This possibility is dismissed by the Global Warming Establishment because the brightness of the sun does not change much during a Minimum. This argument is irrelevant, because the cooling is probably due to the indisputable increase in galactic cosmic rays, which nucleate low clouds that increase the Earth’s albedo.)

    A prospect that is much worse, less likely but not at all impossible, is that the current collapse of the geomagnetic field means that the transition has begun from the Holocene to the next glacial stage of the Quaternary Glaciation. That would be a disaster without any precedent in recorded history, with most advanced northern nations ground to dust under ice sheets 3 km thick.

  9. attention that the statistical averages may have been influenced by external effects, which may have altered the thermal values. It is important to evaluate if the weather stations are efficient and in accordance with the survey, compare the data with the real weather conditions, observing the configuration of the jet stream. remember that every thermal variation is generated by the masses of air carried by the Jet Stream, the thermal statistic must be observed with the real atmospheric conditions, to understand the cause of the variations, the thermal persistence built by the jet stream. Remember that there is no peer review document confirming that CO2 controls the Jet Stream.

  10. Graeme Mochrie says:

    An interesting result Clive. What does it mean? It’s the atmosphere slightly moister? A small increase in relative humidity might give this sort of result.

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