125: Queensland revisited - temperature trends STABLE to 1980

In Post 24 I interrogated the temperature data of Queensland. This Australian state had 28 long stations and a further 85 medium stations in its Berkeley Earth (BE) dataset as listed here. Averaging the anomalies from these 113 stations resulted in a mean temperature anomaly (MTA) that appeared to exhibit a warming of 0.7°C since 1900 as shown in Fig. 125.1 below. But is this the true picture? In this post I will show how the data can be reinterpreted, and thus deliver different results without altering the actual data.

Fig. 125.1: The mean temperature change for Queensland since 1887. The best fit is applied to the monthly mean data from 1901 to 2004 and has a positive gradient of +0.74 ± 0.08 °C per century.

The first problem with the data in Fig. 125.1 is that not all the 113 stations used are of equal length. That means that the MTA before 1905 is dependent on data from less than twenty stations rather than over one hundred as was the case in the 1980s, as the graph in Fig. 125.2 below indicates. This suggests that the data after 1920 will be more reliable than the data before.

Fig. 125.2: The number of station records included each month in the mean temperature anomaly (MTA) trend for Queensland in Fig. 125.1.

Then there is the impact of the fitting range. Applying linear regression to the entire range of data is often inappropriate because the data may have different behaviours or trends at different times. This appears to be the case for the data in Fig. 125.1 as data after 1975 is clearly behaving differently to data before that date.

So suppose we look just at data after 1920 and only fit to data before 1980. Then the picture changes from that presented in Fig. 125.1. The best fit trend line to the data now rises less steeply by only 0.2°C or so before 1980 (see Fig. 125.3 below), and while there is a larger jump after 1975 of about 0.3°C again, this appears to be temporary as the temperature returns to trend after 2010 (although that may just be a temporary reversal). So changing the interval of the linear regression fit can also change the result, or at least change our perceptions, interpretations and conclusions.

Fig. 125.3: The mean temperature change for Queensland since 1920. The best fit is applied to the monthly mean data from 1921 to 1980 and has a positive gradient of +0.29 ± 0.19 °C per century.

What is more, this temperature rise from 1921 to 1980 seen in Fig. 125.3 is more consistent with that seen for the longest temperature record for the state, Brisbane Regional Office (ID 152224), as shown in Fig. 125.4 below. Unusually, this record shows only modest warming despite coming from the middle of the largest urban area in the state. As I will show in future posts, the urban heat island (UHI) effect, where large urban areas lead to a greater warming of the local environment than is seen in more rural areas, or for the region as a whole, can be a serious issue. It usually results in greater warming for stations in large, dense, urban environments compared to the regional average, not less. But not here.

Fig. 125.4: The mean temperature change for Brisbane since 1887. The best fit is applied to the monthly mean data from 1901 to 2004 and has a positive gradient of +0.22 ± 0.08 °C per century.

All this indicates the difficulties in interpreting temperature data correctly. Not all times in history have equal quality of data, and even if they did, the natural variability in that data means that you need long time intervals to see the true trend. And even then your conclusions will be affected by your choices in how the data is analysed.

So which is the better interpretation of the data, Fig. 125.1 or Fig 125.3? My opinion is Fig. 125.3 because it focuses on the better data. The data analysis also fits to data that is less variable, and therefore more reliable. It is too early to know if the temperature rise after 1975 is part of a trend or whether it is just temporary, so the better approach is to treat it almost as a separate dataset and compare it with what went before. 

The temperature dips in Fig. 125.1 before 1910 are also of questionable veracity. Are they the latter part of an upward trend or are they just just natural variability? Without extra data before 1880 we don't know, and even if that upward trend exists, then why does it exist? Because it can't be caused by rises in CO₂ because those rises were negligible before 1910. In fact CO₂ levels in 1910 are estimated to be less than 300 ppm which is a rise of only 6% since 1800. That is nowhere near enough to produce temperature rises of 1°C or more. In fact it would barely result in rises of 0.1°C (see Fig. 87.3 in Post 87).

But of course not everyone sees things this way. One problem with climate science is the amount of data adjustments that are used to correct for perceived data flaws in the temperature data. But as I have shown repeatedly throughout this blog, those adjustments appear hard to justify from any statistical perspective. The raw data is far more reliable than is often assumed, and this can be evidenced by the repeated behaviours seen in temperature trends based on raw data from neighbouring regions that consistently correlate. Many (but not all) of these adjustments also appear to add warming more often than they reduce it, and so appear to exaggerate the amount of climate change that is occurring.

But perhaps one of the most concerning aspects of temperature adjustments is that they are not permanent. The same data often continues to be readjusted over time, and more often each adjustment makes the claims for the warming trend even greater. As exhibit #1 I give you the Australian Bureau of Meteorology (BoM). According to the BoM the climate of Queensland has warmed by about 1.65°C since 1910 as shown in Fig. 125.5 below. Yet the raw data in Fig. 125.1 suggests that the warming is less than half this value and Fig. 125.3 suggests it may be less than 0.3°C. The problem is that the data shown in Fig. 125.5, which is the official BoM version for July 2022, is rather different from the version published in 2010.

Fig. 125.5: The mean temperature change for Queensland since 1910 according to BoM in 2022. The best fit line has a positive gradient of 1.5 °C per century.

In 2010 the temperature trend for Queensland according to the BoM was as shown in Fig. 125.6 below (h/t Ken's Kingdom). Yes it has twelve years less data, but that is not the only difference. Many of the temperature anomalies before 2010 have rather different values compared to now, and so too does the linear trend which was only 1.0°C per century; this despite there being no change in the 30-year reference period of 1961-1990. Now some of the change in linear trend may be due to the extra data after 2010, but not all. It is quite clear that most of the annual anomalies before 1980 in Fig. 125.6 are larger or less negative than was the case for anomalies for the same year in Fig. 125.5 above, while anomalies for most years after 1980 in Fig. 125.6 have smaller values when compared to the corresponding anomaly in Fig. 125.5.

Fig. 125.6: The mean temperature change for Queensland since 1910 according to BoM in 2010. The best fit line has a positive gradient of 1.0 °C per century.

It may be difficult for some readers to spot the difference because we are talking of changes of less than 0.2°C in the height of the bars, but if we overlay the data from Fig. 125.6 on top of that from Fig. 125.5 the differences become more apparent. This is done in Fig. 125.7 below with the 2010 data from Fig. 125.6 coloured green (for positive vales) or sea-green (for negative values) and being slightly translucent so that the red and blue coloured bars from 2022 can be seen underneath.

Fig. 125.7: A comparison of BoM annual temperature anomalies for Queensland from 2022 (red and blue) and 2020 (green).

What Fig. 125.7 shows quite clearly is that the temperature anomalies before 1980 were up to 0.2°C greater back in 2010, while those after 1980 were up to 0.2°C smaller in value. In other words, the extra adjustments made to the data since 2010 have added up to 0.4°C of warming. And yet neither set of data is comparable to the unadjusted data in Fig. 125.3 where the warming is estimated at less than 0.3°C.

Summary

Re-analysis of the unadjusted Queensland temperature data from Post 24 shows that the state may have warmed by as little as 0.3°C since 1920 (see Fig. 125.3).

The most extreme analysis of the unadjusted data indicates that the warming since 1900 is less than 0.8°C (see Fig. 125.1).

According to the Australian Bureau of Meteorology (BoM) in 2010, there had been 1.0°C of warming from 1910 to 2010 (see Fig. 125.6).

In 2022 the BoM now claims that warming since 1910 has increased to 1.65°C (see 125.5).

Adjustments made to the 1910-2010 data by the BoM since 2010 appear to have added up to 0.4°C of warming (see Fig. 125.7). So up to 60% of the 0.65°C temperature rise claimed by the BoM since 2010 could be due to data readjustments for data before 2010.

32. Papua New Guinea - temperature trends 0.4°C WARMING (moderate)

I had thought about combining the temperature data for Papua New Guinea (PNG) with that of Indonesia, just as I did with East Timor (Timor Leste) in the previous post. Like East Timor, PNG shares an island (in this case Papua) with Indonesia, so from that point of view it would be logical. However, in the end I decided there was enough data in Indonesia, and extending the analysis to PNG would not only increase the data analysis complexity, but also the geographical area of coverage, and that would be too much. 

Like Indonesia, PNG has only one long station with a temperature record longer than 1200 month (Port Moresby AP - Berkeley Earth ID: 157418). It also has seven medium stations with records of more than 480 months of temperature data, and there are approximately 30 other shorter records that are too small to be useful. One of the medium stations (Port Moresby - Berkeley Earth ID: 19383) is excluded from the following analysis even though it contains data that suggests temperatures in the late 1800s were up to 1.0 °C higher than in the early 20th century. This is because: a) it is close to another long station (Port Moresby AP - Berkeley Earth ID: 157418) which has longer and more complete data in the 20th century; and b) because it has no data after 1941, and so its monthly reference temperatures (MRTs) cannot be calculated for the same time period (1961-1990) as the other stations. For an explanation of MRTs, and how they are used to calculate the monthly temperature anomaly, see Post 4.

Fig. 32.1: Temperature trend for all long and medium stations in Papua New Guineasince 1900 derived using the Berkeley Earth adjusted data. The best fit linear trend line (in red) is for the period 1912-1999 and has a gradient of +0.83 ± 0.03 °C/century.

Averaging the Berkeley Earth adjusted anomaly data from the eight long and medium stations yields the temperature trends shown in Fig. 32.1 above. These are very similar to the versions published by Berkeley Earth and shown below in Fig. 32.2, which suggests that the weightings for each station used by Berkeley Earth in their averaging process were fairly equal.

 

 Fig. 32.2: Temperature trend for Papua New Guinea since 1880 according to Berkeley Earth.

 

The high level of agreement between the data in Fig. 32.1 and Fig. 32.2 allows us to repeat the process for the raw anomaly data without the need for different station weighting coefficients. The result is shown below in Fig. 32.3. 

 

Fig. 32.3: The temperature trend for Papua New Guinea since 1900. The best fit is applied to the interval 1912-1999 and has a gradient of 0.44 ± 0.07 °C per century. The temperature changes are relative to the 1961-1990 average.

It can be seen that once again, the temperature trend derived from the raw anomaly data in Fig. 32.3 is significantly different in its degree of warming compared to that derived using the Berkeley Earth adjusted data in Fig. 32.1 and Fig. 32.2. While there are qualitative similarities (the peaks at 1910 and 2000, and the local minimum around 1965), the overall temperature rise seen in the raw data is much less. At worst, the temperature rise seen in the raw data in Fig. 32.3 is less than 0.4 °C, while the 5-year average in 2010 is barely higher than the peaks in the same curve before 1940.

The 5-year average in 2010 is also only 0.3 °C higher than the 80-year average for 1903-1982. This is hardly conclusive evidence of cataclysmic global warming. In fact the 5-year mean in 2010 is less than two standard deviations above the pre-1982 mean. It is, therefore, within the expected range for natural fluctuations for the given timescale of 110 years.

The data in Fig. 32.3 is also noticeably noisier before 1950 than it is after 1950. This is because there are only two temperature records with data before 1950, and only one of those, Port Moresby AP (Berkeley Earth ID: 157418), is reasonably continuous.

A final point of interest is the qualitative similarity between the data for PNG in Fig. 32.3 above, and that for Queensland shown in Fig. 24.4 previously. The biggest difference appears to be the overall temperature rise which is significantly higher in the case of Queensland (0.74 °C per century compared to 0.44 °C per century for PNG).

Fig. 32.4: The contribution of Berkeley Earth (BE) adjustments to the anomaly data after smoothing with a 12-month moving average. The linear best fit to the data is for the period 1904-2012 (red line) and the gradient is +0.34 ± 0.03 °C per century. The orange curve represents the contribution made to the BE adjustment curve by breakpoint adjustments only.

It is clear that the Berkeley Earth adjusted data for PNG results in almost double the temperature rise since 1900 compared to that found using the raw data. The actual difference is shown in Fig. 32.4 above and amounts to about 0.34 °C per century, most of which is due to breakpoint adjustments.

Conclusions

1) Papua New Guinea has experienced a modest temperature rise since 1960 (perhaps 0.5°C), but overall, temperatures have barely risen by more than 0.3 °C since 1900 (see Fig. 32.3).

2) The temperature trend for Papua New Guinea from 1900 to 2013 is broadly similar to that seen in neighbouring countries and regions (e.g. Indonesia, Australia and New Zealand).

3) The fluctuations in temperature for Papua New Guinea appear broadly consistent with natural variability. The magnitude of these temperature changes clearly challenge the current prevailing paradigm regarding anthropogenic global warming of more than 1.0 °C.

4) The adjustments made to the temperature data by Berkeley Earth have once again had a material and significant impact on the overall temperature trend. It is only with the inclusion of these adjustments that the temperature trend for Papua New Guinea resembles that of the IPCC HadCRUT4 temperature record.

5) The lack of data means that the temperature record of Papua New Guinea before 1950 is extremely uncertain. It can only be speculated upon based on similarities with neighbouring countries.

 

Addendum

The maximum number of temperature records used to derive the mean temperature trend in Fig. 32.3 is seven but before 1940 this reduces to two or less (see Fig. 32.5 below). See here for a complete list of all stations in Papua New Guinea.

 

Fig. 32.5: The number of station records included each month in the mean temperature anomaly (MTA) trend for Papua New Guinea in Fig. 32.3.

 

25. A summary of temperature trends in Australia

In the seven posts previous to this I analysed the temperature trends in each of the seven major Australian states (ACT was combined with NSW) since instrumental temperature records began in about 1840. The results are summarized below.

In the following graphs the blue curve is the 10-year average temperature for the state relative to the decade 1991-2000 based on the actual unadjusted raw temperature data. The red line is the best fit to that data for the 100 year interval 1901-2000. The orange curve is the trend based on Berkeley Earth adjusted data. This is also defined relative to its mean for the decade 1991-2000.

Fig. 25.1: Temperature trends for NSW. The gradient of the best fit line is 0.08 ± 0.11 °C per century.

Fig. 25.2: Temperature trends for Victoria. The gradient of the best fit line is -0.04 ± 0.09 °C per century.

Fig. 25.3: Temperature trends for Tasmania. The gradient of the best fit line is 0.72 ± 0.11 °C per century.

Fig. 25.4: Temperature trends for South Australia. The gradient of the best fit line is 0.40 ± 0.11 °C per century.

Fig. 25.5: Temperature trends for Western Australia. The gradient of the best fit line is 0.76 ± 0.11 °C per century.

Fig. 25.6: Temperature trends for Northern Territory. The gradient of the best fit line is 0.09 ± 0.09 °C per century.

Fig. 25.7: Temperature trends for Queensland. The gradient of the best fit line is 0.69 ± 0.13 °C per century.

Conclusions

1) The Berkeley Earth adjusted data trends appear to closely follow the actual data trends for the period after 1970. However, before 1970 the two trends often diverge significantly.

2) Even after divergence, the Berkeley Earth adjusted data trend has almost identical features to the corresponding actual data trend. These features include the patterns of peaks, and the large changes in gradient at similar points in time. In fact the adjusted and unadjusted trend lines appear to show near identical instances of abrupt discontinuities and rapid temperature changes at various points along their respective records.

3) Linear regression fits to temperature record data cannot adequately represent the complexity of the data. For example, a 100-year best fit to the NSW data in Fig. 25.1 yields a gradient of 0.08 °C per century for the period 1901-2000, yet for the interval 1881-1980 this changes to -0.41 ± 0.11 °C per century. Likewise, changing the interval of the best fit for Northern Territory to 1886-1985 also changes the gradient to -0.41 ± 0.11 °C per century, while a best fit interval of 1871-1970 for South Australia results in a gradient of -0.60 ± 0.12 °C per century. In other words, the gradient of the best fit line depends strongly on the measurement interval chosen for the best fit.

4) The temperature trends based on actual data (not the Berkeley Earth adjusted data) suggest that for most states, except maybe Queensland, average temperatures in the latter part of the 20th century were lower than those in the latter part of the 19th century.

5) In most states the majority of any climatic warming has occurred after 1980.

Links to all posts with my original analysis are listed below or on the sidebar.

New South Wales (and ACT)

Victoria

Tasmania

South Australia

Western Australia

Northern Territory

Queensland

24. Queensland - temperature trends 0.7°C WARMING

i) Weather station quality and distribution

Queensland is the second largest state by area in Australia, but only the third largest by population. Given that the provision of weather station records around the world appears to broadly correlate with a combination of population and GDP, one would therefore expect Queensland to have more temperature records than smaller states such as Tasmania, South Australia and Northern Territory, but less than states with larger populations such as Victoria and New South Wales (NSW). This is broadly the case, although not in the case of Victoria.

Queensland has 112 stations with over 480 months of data (medium stations), of which 28 are long stations with more than 1200 months of data. This is not as extensive as NSW but more than Victoria. However, while Victoria has fewer stations in total, those long stations that it does have tend to have longer records. The major deficiency of the Queensland temperature records is that none pre-date 1887.

Fig. 24.1: The locations of long stations (large squares) and medium stations (small diamonds) in Queensland. Those stations with a high warming trend since 1887 are marked in red.

If we look at the distribution of weather stations in Queensland (see Fig. 24.1 above) we see that it is fairly even. There is a higher concentration around Brisbane and the Coral Sea coast compared to inland, but the coverage is generally fairly good, if a little sparse around the border with South Australia.


ii) The Berkeley Earth (BE) mean temperature trend

As the stations in Queensland are fairly evenly distributed (see Fig. 24.1 above), it means weighting coefficients based on the local station density are not necessary when combing stations into a regional average. This can be seen when averaging all the Berkeley Earth adjusted anomalies for each month. The resulting overall trend that is produced using a simple averaging process for that data (and plotted in Fig. 24.2) is very similar to that claimed by Berkeley Earth using their weighted averaging process (see Fig. 24.3).

Fig. 24.2: Temperature trend for all long and medium stations in Queensland since 1887 derived using the Berkeley Earth adjusted data. The best fit linear trend line (in red) is for the period 1951-2003 and has a gradient of +1.74 ± 0.14 °C per century.

The Berkeley Earth trend in Fig. 24.2 above is my reconstruction of the Berkeley Earth adjusted trend. It was derived simply by averaging the adjusted anomalies for all long and medium stations. These adjusted anomalies were found in the data files for each station on the Berkeley Earth site. An example for Brisbane Regional Office Roof (Berkeley Earth ID: 152224) is found here. The adjusted anomaly data is in the 8th column. The raw temperature data is in the 3rd column.

The temperature trend in Fig. 24.2 clearly exhibits a period of stability from 1880 up to 1950, followed by a much stronger warming phase. This is replicated in the official Berkeley Earth version shown in Fig. 24.3 below, the original online version of which can be found here.

It is apparent that most of the prominent features (i.e. major peaks and troughs) displayed by both the 12-month moving average and the 10-year moving average for my reconstruction from the Berkeley Earth adjusted anomalies (shown in Fig. 24.2 above) correspond to similar features at almost identical times in the official Berkeley Earth trend shown below in Fig. 24.3. This implies that only a simple average of the data from Queensland is necessary in order to determine the overall trend for the region, and no station weighting (either based on their area of coverage or statistical significance) is needed.

Fig. 24.3: Temperature trend for Queensland since 1840 according to Berkeley Earth.

The degree of agreement between the data in Fig. 24.2 and Fig. 24.3 also suggests that the trend of the warming period in Fig. 24.2 above, which is approximately 1.74 ± 0.14 °C per century and denoted by the red line, will also correspond to the warming trend post-1920 in Fig. 24.3. This warming trend equates to a total warming since 1951 of about 1.0 °C. If we look at the raw temperature data though (rather than the Berkeley Earth adjusted data), we get a slightly different picture.


iii) Temperature trend based on long and medium station records

In this section I have applied the same simple averaging process to the raw temperature anomalies as was deployed in the last section for the Berkeley Earth adjusted anomalies. The raw anomalies for each dataset were derived by subtracting the monthly reference temperature (MRT) for that dataset from each monthly reading in that dataset. The 12 different MRTs were derived by averaging the temperature for each month in the dataset over the period 1961-1990. Then the mean anomaly for each month was determined by averaging all the values for that month from the different station datasets. The result is the regional monthly average shown in Fig. 24.4 below.

Fig. 24.4: Temperature trend for long and medium stations in Queensland since 1887. The best fit linear trend line (in red) is for the period 1901-2004 and has a gradient of 0.74 ± 0.08 °C per century.

The temperature trend in Fig. 24.4 is clearly positive over the entire time-frame, although the upward trend is more pronounced after 1950. This is different from the trend for all the other states in Australia, most of which exhibited a clear downward temperature trend before 1940. This difference may be due to the lack of data in Queensland before 1890, or it may be the result of regional variation. It should also be noted though that the trend for Queensland in Fig. 24.4 is very similar to that found for South Australia from 1900 onwards (see Fig. 21.5 here). Overall, the trend in Fig. 24.4 amounts to a total temperature rise since 1890 of 0.89 °C. This is slightly less than that seen for the Berkeley Earth adjusted data in Fig. 24.2.


iv) Breakpoints and other adjustments

Subtracting the mean temperature anomaly shown in Fig. 24.4 from the Berkeley Earth version derived using adjusted anomalies yields the data in Fig. 24.5 below.

Fig. 24.5: The difference between the raw anomaly data in Fig. 23.4 and Berkeley Earth adjusted anomaly data, together with a linear best fit for the period 1901-2010 (red line). The gradient of the best fit line is +0.02 ± 0.04 °C per century. The yellow curve represents the contribution made to the difference data by breakpoint adjustments.

The data in Fig. 24.5 appears to indicate that the Berkeley Earth adjustments are more or less neutral. This is not true, for while the overall contribution to the trend curve is minimal, there are within this two separate contributions which are not.

The first is for the period 1887-1950. Here the adjustments raise the temperatures before 1990, thereby flattening the curve. Then after 1951 the contribution is to increase the slope. The slope of the adjustments after 1951 is +0.15 ± 0.09 °C per century, while before 1951 it is -0.42 ± 0.09 °C.

Fig. 24.6: The contribution of Berkeley Earth adjustments to the anomaly data after smoothing with a 12-month moving average. The linear best fit to the data is for the period 1901-2010 (red line) and the gradient is +0.02 ± 0.04 °C per century. The orange curve represents the contribution made to the adjustment curve by breakpoint adjustments only.

The significant feature of the total adjustment data in Fig. 24.5 (the blue curve with black markers) is the amount of noise it contains, amounting to fluctuations of up to ±0.5 °C. Remarkably, a 12-month moving average completely removes this noise. This implies that the fluctuations are not random, but are periodic, with a period of 12 months. The obvious source of these fluctuations is the difference in the MRT between the values I have derived in my calculation of the temperature anomaly, and the homogenized values used by Berkeley Earth that also rely on data from neighbouring station records.


v) Conclusions

1) Queensland is the only state in Australia that exhibits a significant warming trend.

2) It is also the only state with no evidence of warming before 1890. That is because it is the only state with no significant data before 1890 (other than ACT).

3) The total temperature rise since 1890 is less than 0.9 °C.