105. US southern states - summary of BE temperature adjustments

In my previous post I summarized the temperature trends since 1900 of the six US states closest to the Gulf of Mexico (Texas, Louisiana, Mississippi, Alabama, Georgia and Florida). All the trends were constructed using data from the longest available temperature records in the state, all involved averaging the temperature anomalies from over 90 different station records, and none exhibited a significant positive warming trend.

Yet in every case the official Berkeley Earth (BE) trend does exhibit warming, often lots of it. The difference of course is largely down to the adjustments that Berkeley Earth make to the data via homogenization, Kriging, gridding and of course breakpoint alignment. In the post for each state (the links are here: Texas, Louisiana, Mississippi, Alabama, Georgia and Florida) I have quantified the magnitude of these adjustments, but I thought it would also be instructive to summarize them in one post just so that their full impact can be seen and compared.

The adjustments shown in the graphs below are of two types. The orange curve is the mean adjustment each month solely from breakpoint adjustments while the blue curve is the mean adjustment relative to unadjusted data from all sources of correction. This will also include homogenization, Kriging and gridding in addition to breakpoints, but it will also be affected by any difference in the chosen period for calculating the monthly reference temperatures (MRTs). The last of these will, however, only change the offset of the blue curve in the vertical direction relative to the orange one, not its slope or total change over time.

The graphs below indicate that the BE adjustments to the temperature data add between 0.5°C and 1.2°C to the final BE temperature trends. Given that we are constantly being told by climate scientists that the total global warming experienced so far is about 1.2°C, I would suggest that this is a bit of a problem.

Fig. 105.1: The Berkeley Earth (BE) temperature adjustments for Texas since 1900. The linear best fit (red line) to these adjustments for the period 1911-2010 has a positive gradient of +0.568 ± 0.003 °C per century.

Fig. 105.2: The Berkeley Earth (BE) temperature adjustments for Louisiana since 1900. The linear best fit (red line) to these adjustments for the period 1911-2010 has a positive gradient of +0.731 ± 0.004 °C per century.

Fig. 105.3: The Berkeley Earth (BE) temperature adjustments for Mississippi since 1900. The linear best fit (red line) to these adjustments for the period 1931-2010 has a positive gradient of +1.300 ± 0.007 °C per century.

Fig. 105.4: The Berkeley Earth (BE) temperature adjustments for Alabama since 1900. The linear best fit (red line) to these adjustments for the period 1931-2010 has a positive gradient of +1.231 ± 0.012 °C per century.

Fig. 105.5: The Berkeley Earth (BE) temperature adjustments for Georgia since 1900. The linear best fit (red line) to these adjustments for the period 1911-2010 has a positive gradient of +1.087 ± 0.006 °C per century.

Fig. 105.6: The Berkeley Earth (BE) temperature adjustments for Florida since 1900. The linear best fit (red line) to these adjustments for the period 1941-2010 has a positive gradient of +0.611 ± 0.010 °C per century.

104. US southern states - summary of temperature trends

Over the last month I have examined the temperature trends of five different US states (Louisiana, Mississippi, Alabama, Georgia and Florida) that surround, or are within 100km of (in the case of Georgia), the Gulf of Mexico. These all appear to have similar trends to that of Texas that I examined in Post 52. All have negative or stable temperature trends over the last 100 years. For comparison their temperature trends are republished here with identical data ranges (from 1900) and fitting ranges (1911-2010). What is clear is that none of these trends is remotely similar to either the Berkeley Earth (BE) versions for each state based on adjusted data, or the global trends published by NOAA, NASA-GISS, BE, HadCRU etc.

Fig. 104.1: The mean temperature change for Texas. The best fit has a slight negative gradient of -0.15 ± 0.15 °C per century.

Fig. 104.2: The mean temperature change for Louisiana. The best fit has a negative gradient of -0.38 ± 0.15 °C per century.

Fig. 104.3: The mean temperature change for Mississippi. The best fit has a negative gradient of -0.76 ± 0.17 °C per century.

Fig. 104.4: The mean temperature change for Alabama. The best fit has a negative gradient of -0.72 ± 0.17 °C per century.

Fig. 104.5: The mean temperature change for Georgia. The best fit has a negative gradient of -0.76 ± 0.16 °C per century.

Fig. 104.6: The mean temperature change for Texas. The best fit has a slight positive gradient of +0.08 ± 0.13 °C per century.

98. What happened to Louisiana temperatures in 1957?

Fig. 98.1: Global average land temperatures since 1850 according to Berkeley Earth.

In my previous post looking at the temperature trend for Louisiana (Post 97) I showed that the mean temperature in the region had declined by almost 0.2°C in the last century or so. This is in sharp contrast to the claim from most climate scientists that average temperatures have increased by almost 1.2°C in that time, and that this increase is even greater on land. In fact Berkeley Earth claims the increase in land temperatures since 1850 to be in excess of 2°C (see Fig. 98.1 above). But while analysing the Louisiana data one feature stood out that makes me query both the results of my last post and the analysis processes of Berkeley Earth (BE). 

In 1957 the temperature appears to drop suddenly and permanently by about 0.615°C (see black arrow on Fig. 98.2 below). What makes this feature significant is that similar temperature falls at identical times can be seen in the most of the individual temperature records for Louisiana. But they can also be seen in the temperature trends of neighbouring states like Texas. 

So is this temperature drop due to a sudden and large, natural change in the local climate? Or is it due to a change in the data measurement and analysis? If it is the latter then it needs to be corrected for and that will change drastically the true temperature trend. If it is the former then it raises serious questions about how the climate changes over time. In this post I will look at this feature in more detail and try to answer those questions.

 

Fig. 98.2: The mean temperature change for Louisiana relative to the 1951-1980 monthly averages. The best fit (white line) is applied to the monthly mean data from 1911 to 2010 and has a negative gradient of -0.38 ± 0.15 °C per century. The arrow and red line indicate the position and size of the data discontinuity.

The data in Fig. 98.2 above is the part of the same data that was presented previously in Fig. 97.1 of Post 97. In this case I am concentrating only on data after 1910 which, as I pointed out in Post 97, is the most reliable as it all results from an averaging of over forty distinct temperature records (see Fig. 97.2). The white line in Fig. 98.2 is the best fit to the data from 1911 to 2010 and has a strong negative gradient of -0.38°C per century. This is somewhat more negative than the trend in Fig. 97.1 because the fitting range is different. This shows how the value of the best fit gradient can be strongly influenced by the data range, particularly when the data exhibits large fluctuations.

The point of interest in the data above is in 1957 (as indicated by the large black arrow) where the mean temperature appears to drop suddenly and permanently by about 0.615°C. This can be seen clearly in the yellow line which is the 5-year moving average of the monthly anomaly data. It is also illustrated by the red line which is effectively two separate lines: the average temperature for 1921-1960 and the average for 1961-1990. In both cases the discontinuity is clear. The magnitude of the vertical discontinuity can be estimated from the discontinuity in the red line and is 0.615°C. 

Fig. 98.3: The mean temperature change for Louisiana after breakpoint adjustment. The best fit is applied to the monthly mean data from 1911 to 2010 and has a positive gradient of +0.54 ± 0.15 °C per century.

The next step is to remove the discontinuity by shifting upwards all the data after the start of 1958 in Fig. 98.2 by the size of the discontinuity, 0.615°C. The result is shown in Fig. 98.3 above. Two things are striking about the result. First, the gradient of the best fit is now strongly positive (+0.54°C per century) suggesting that the climate is warming. And secondly, the data just looks better with a more consistent trend. Of course just because data looks nicer does not prove that it is more reliable or more accurate.

 

Fig. 98.4: The total contribution of Berkeley Earth (BE) adjustments to the Louisiana temperature data. The orange curve shows the contribution just from breakpoint adjustments. The blue curve represents the total BE adjustments including those from homogenization. The linear best fit (red line) to the total BE adjustments for the period 1911-2010 has a positive gradient of +0.731 ± 0.004 °C per century.

The process I have employed here is virtually identical in concept to the breakpoint adjustments used by Berkeley Earth (BE). The main difference is that I have only applied one adjustment to the final mean temperature data whereas Berkeley Earth apply multiple adjustments of differing magnitudes and times to almost every station dataset. The sum total of those BE adjustments for the Louisiana data is shown in Fig. 98.4 above and the result is a huge warming trend of +0.73°C per century. This is warming that is added to the original data as I showed in Post 97. Yet the 0.6°C discontinuity in the middle of 1957 still remains in the adjusted BE data even after their adjustments have been made as the arrow in Fig. 98.5 below indicates. So the BE adjustments have not corrected the most glaring issue with the original data, which does rather raise a lot of questions regarding the accuracy and validity of the BE adjustments that are made.

Fig. 98.5: Temperature trends for Louisiana based on Berkeley Earth adjusted data from the 90 longest station data records. The best fit linear trend line (in red) is for the period 1911-2010 and has a gradient of +0.37 ± 0.05°C/century.

This is not the first time I have encountered these sudden jumps in temperature data. A similar upward jump in temperature of over 1°C can be seen in the temperature trend for Europe in 1988 (see Fig. 44.1 in Post 44). So what is the cause? At the moment I can only think of two explanations: a natural phenomenon that suddenly changes the local climate, or a sudden change in measurement equipment or methodology that is applied across all stations in a region simultaneously. But so far I can find no evidence for either. Of course the natural phenomenon may not have occurred in 1957 or at any other recent time before that. The complex dynamics of the Earth's climate could mean we are seeing the ripples now of forcing events many centuries ago. In Post 9 and Post 17 I have investigated chaotic effects in the temperature record and found evidence of fractal behaviour that can persist for centuries.

Fig. 98.6: The mean temperature change for Texas relative to the 1961-1990 monthly averages. The best fit (white line) is applied to the monthly mean data from 1911 to 2010 and has a negative gradient of -0.15 ± 0.15 °C per century. The arrow and red line indicate the position and size of the data discontinuity.

What is clear is that this temperature discontinuity is not restricted to Louisiana. The same data anomaly can be seen in the temperature trend for Texas that I analysed in Post 52. This is shown in Fig. 98.6 above with the breakpoint adjusted temperatures shown in Fig. 98.7 below.

 

 Fig. 98.7: The mean temperature change for Texas after breakpoint adjustment. The best fit is applied to the monthly mean data from 1911 to 2010 and has a positive gradient of +0.56 ± 0.15 °C per century.

After the breakpoint adjustment the temperature trend for Texas is now positive and virtually identical to that of Louisiana in Fig. 98.3. There also appears to be a strong correlation between the 5-year moving average (yellow curves) of each. This suggests that the region could have warmed by about 0.5°C over the last one hundred years. However, as I pointed out in Post 52, direct anthropogenic surface heating (DASH) or waste heat equating to about 0.7 W/m² is probably currently warming Texas by up to 0.3 °C compared to 1850. That only leaves about 0.2°C for carbon dioxide induced climate change. This in line with the temperature rise I estimated in Post 87 and a long way short of the 2°C claimed by Berkeley Earth and others. So even with this adjustment there is little evidence to support severe carbon dioxide induced climate change in Louisiana or Texas.

52. Texas - temperature trends STABLE

If there is one country in the world where you expect dramatic climate change on account of its own greenhouse gas emissions, then that country would probably be the USA. And if there is one state in the USA that embodies the American passion for fossil fuels, that state would be Texas. So when Texas was hit by extreme weather earlier this month in the shape of winter storms Uri and Viola, which resulted in millions Texans losing their electricity supply, then it was only a matter of time before people started screaming "climate change". Because even extreme cold weather is a symptom of anthropogenic global warming (AGW) and climate change (apparently). Unfortunately there is just one problem: there has been no global warming in Texas. So, given the topical nature of the Texas climate at the moment, I thought I would take a temporary break from Europe and take a closer look at climate change in Texas.

The mean temperature trend for the region is shown in Fig. 52.1 below. This was achieved by averaging the temperature anomalies from the 220 longest weather station temperature records in the region, where the temperature anomalies were measured relative to the monthly reference temperature (MRT) in each case. The MRTs were calculated for the interval 1961-1990. For a more detailed explanation of the MRT calculation process, see Post 47.

 

 Fig. 52.1: The temperature trend for Texas since 1840. The best fit is applied to all the data and has a slight positive gradient of 0.05 ± 0.08 °C per century. The monthly temperature changes are defined relative to the 1961-1990 monthly averages. 

 

For 160 years up to 2013 there was no anthropogenic global warming (AGW) occurring in Texas. In fact the mean temperature for the region rose by less than 0.08 °C. And while there is some evidence of a rise in temperature since the 1960s, this still leaves temperatures lower than in the first half of the 20th century.

 

Fig. 52.2: The number of station records included each month in the mean temperature trend for Texas.

 

The temperature trend shown in Fig. 52.1 is the average of up to 220 of the longest temperature records for the state as illustrated in Fig. 52.2 above. All the temperature records have over 720 months (or 60 years) of data, of which 64 are long stations with more than 1200 months of data. These 220 stations are also distributed fairly evenly over the region as shown in Fig. 52.3 below. This means that a simple average of all the temperature anomalies without additional weighting coefficients should yield a mean temperature trend that is reasonably accurate, even though there does appear to be a slightly higher density of stations in the east of the state than in the west. This conjecture will be tested by comparing results later.

 

Fig. 52.3: The locations of long stations (large squares) and medium stations (small diamonds) in Texas. Those stations with a high warming trend are marked in red.

 

The other point of note about the stations in Fig. 52.3 is the high proportion of stations that appear to exhibit no warming; over 70% of them. Here, a warming station is defined as being one where the temperature gradient is more than twice the uncertainty in the trend and the total temperature rise also exceeds 0.25 °C. 

This high proportion of cool stations is unusual but not unique. It has seen in many other places including New South Wales and Victoria. What it appears to highlight is the strong correlation that exists between the degree of warming seen at a particular location and the size of the local population, degree of economic development and the length of the temperature record itself. 

Short, younger temperature records tend to exhibit greater warming because they only have data from the latter part of the 20th century and post 2000, and increased urbanization in the latter part of the 20th century is clearly warming the local environment. In fact, direct anthropogenic surface heating (DASH) or waste heat equating to about 0.7 W/m² has probably warmed Texas by up to 0.3 °C since 1850. In addition, the short length of modern station records means that they do not include any of the natural variation seen in earlier times such as naturally high temperatures seen in the 19th century. In addition, many rural stations appear to exhibit very little warming, while major cities like Jakarta, Sydney and Melbourne can display very large degrees of warming that do not correspond to the climate of the rest of their regions.

What is interesting is comparing the trend based on the original true temperature data in Fig. 52.1 with the equivalent trend based on an average of the adjusted data used by Berkeley Earth. This adjusted data includes the effects of homogenization and breakpoint adjustments that are supposed to improve the quality and accuracy of the data. The mean of the adjusted Berkeley Earth data for the 220 longest station records in Texas is shown in Fig. 52.4 below.

 

Fig. 52.4: Temperature trend in Texas since 1840 derived by aggregating and averaging the Berkeley Earth adjusted data for the 220 longest data records for Texas. The best fit linear trend line (in red) is for the period 1881-2010 and has a gradient of +0.58 ± 0.04 °C/century.

 

Unlike the original data in Fig. 52.1 which exhibits virtually no warming, the Berkeley Earth adjusted data has a strong positive trend of 0.58 °C per century. In total this equates to a warming of over 0.8 °C from 1880 to 2010, while the 10-year moving average suggests an even greater warming of over 1.2 °C. Again, this may be consistent with IPCC reports, but it is not consistent with the actual real data in Fig. 52.1. It is, however, virtually identical to the published Berkeley Earth version shown in Fig. 52.5 below.

 

 Fig. 52.5: The temperature trend for Texas since 1820 according to Berkeley Earth.

 

The similarity of the data in Fig. 52.4 with the Berkeley Earth published version shown in Fig. 52.5 above in effect validates the simple averaging process I have employed, not only for the data in Fig. 52.4, but also for that in Fig. 52.1 as well. It demonstrates that weighted averages are not needed.

Fig. 52.6: The contribution of Berkeley Earth (BE) adjustments to the anomaly data in Fig. 52.4 after smoothing with a 12-month moving average. The blue curve represents the total BE adjustments including those from homogenization. The linear best fit (red line) to these adjustments for the period 1911-2010 has a gradient of +0.568 ± 0.003 °C per century. The orange curve shows the contribution from breakpoint adjustments only.

 

Overall, the Berkeley Earth adjustments appear to add between 0.6 °C and 1.2 °C to the warming of Texas, depending on how you view it. If we consider the net adjustments made to the data (the blue curve in Fig. 52.6 above) which are the difference between the mean anomalies in Fig. 52.1 and Fig. 52.4, these appear to add about 0.6 °C of warming. On the other hand, the difference in the gradients of the best fit lines in Fig. 52.1 and Fig. 52.4 results in over 0.7 °C of warming being added. Either way, these are significant modifications to the original real data that completely change its properties.

 

Summary

1) The mean temperature of Texas has been stable since 1840 (see Fig. 52.1).

2) In contrast, the Texas temperature trend based on Berkeley Earth adjusted data exhibits a warming of over 0.8 °C before 2010 (see Fig. 52.4).

3) Virtually all the warming seen in the Berkeley Earth adjusted data (as denoted by the trend of 0.58 °C per century in Fig. 52.4) can be accounted for by the adjustments made to the data (as seen in the trend of 0.57 °C per century in Fig. 52.6).

4) Adjustments made to the temperature data by Berkeley Earth via breakpoint adjustments and homogenization (see Fig. 52.6) have profoundly changed the magnitude of the warming of the Texas temperature trend since 1840 (see Fig. 52.4) compared with that observed in the raw original data (see Fig. 52.1).