Even though the old state of Czechoslovakia is on the opposite side of Poland to the Baltic States (see Post 51), it has very a similar temperature trend since 1771 (see Fig. 53.1 below). There is a negative trend before 1980, and then a sudden jump in temperatures around 1987-1988. However, there is one significant difference. While the discontinuity in 1987-1988 of +0.93 °C is similar to that seen in the Baltic States, the negative slope beforehand is much greater (-0.45 °C per century compared to only -0.08 °C per century). The result of this is that temperatures in the region before 1830 appear to be even greater than they are now. In fact the mean temperature for 1791-1830 was over 0.1 °C higher than the mean for 1991-2010.
Fig. 53.1: The temperature trend for the Czech Republic and Slovakia since 1771. The best fit is applied to the interval 1781-1980 and has a negative gradient of -0.45 ± 0.07 °C per century. The monthly temperature changes are defined relative to the 1981-2010 monthly averages.
Unfortunately, the quality of the data for this region is not as good as that for the Baltic States. That is why I have combined the current states of the Czech Republic and Slovakia into one post. The extent of the data can be seen in Fig. 53.2 below. While there is data that goes as far back as 1771, it only comes from three stations before 1930, and two before 1900; all are in the Czech Republic.
Fig. 53.2: The number of station records included each month in the mean temperature trend for the Czech Republic and Slovakia when the MRT interval is 1981-2010.
Overall there are 3 long stations in the old state of Czechoslovakia with over 1200 months of data, and all are in the Czech Republic. In addition there are another 25 medium stations with over 480 months of data, of which 12 are in Slovakia. The locations of these stations are shown in Fig. 53.3 below. What is clear is that the medium stations are evenly dispersed while the long stations are all in the north-west of the Czech Republic. It is also clear that most of the medium stations show a warming trend. The reason for this is simple. Almost all are modern stations with data that starts in 1973. Their data therefore coincides with the overall warming period in Fig. 53.1 above from 1973 to 2013. On the other hand, two of the three stations with cooling trends only have data from the 19th century where the overall trend is negative.
Fig. 53.3: The locations of long stations (large squares) and medium stations (small diamonds) in the Czech Republic and Slovakia. Those stations with a high warming trend are marked in red.
The question is, given the paucity of data before 1950, how reliable is the trend in Fig. 53.1 above? In my view the bast way to answer that is by comparing it with neighbouring trends such as those for Germany, Poland and the Baltic States. Other than Poland these all have consistent negative trends in the 19th century and early 20th century. That suggests that the trend in Fig. 53.1 is consistent.
Fig. 53.4: Temperature trend in the Czech Republic and Slovakia since 1771 derived by aggregating and averaging the Berkeley Earth adjusted data for all long and medium stations. The best fit linear trend line (in red) is for the period 1831-1980 and has a gradient of +0.49 ± 0.04 °C/century.
Unfortunately, that is not the view of the climate scientists. If you average the adjusted data created by Berkeley Earth you get the trend shown in Fig. 52.4 above. Now, instead of a negative trend of -0.45 °C per century between 1831 and 1980, we have a positive trend of +0.49 °C per century. This is consistent with the published trend for the Czech Republic shown in Fig. 53.5 below.
Fig. 53.5: The temperature trend for the Czech Republic since 1750 according to Berkeley Earth.
This means that the adjustments made by Berkeley Earth have added up to 1.4 °C of warming since 1830. This van be seen in just as clearly in Fig. 53.6 below where the total adjustments are shown to equate to over 1.3 °C of warming since 1800. The blue curve in Fig. 53.6 is the difference between the real data in Fig. 53.1 and the adjusted data in Fig. 53.4.
Fig. 53.6: The contribution of Berkeley Earth (BE) adjustments to the anomaly data in Fig. 53.4 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 1801-1980 has a gradient of +0.707 ± 0.009 °C per century. The orange curve shows the contribution just from breakpoint adjustments.
Conclusions
1) Czechoslovakia experienced a prolonged cooling from 1800 to 1980 before seeing a rapid warming after 1987.
2) Temperatures today in the Czech Republic and probably Slovakia are still below those seen in the first quarter of the 19th century.
3) Once again Berkeley Earth adjustments to the raw data have added significant warming. In this case up to 1.4 °C.
4) Once again there is a large positive temperature discontinuity of almost 1 °C around 1987-1988. Origin unknown!
No comments:
Post a Comment