If you are searching for climate change in Hungary then you are likely to be disappointed. Yes, there is variability: there always is. But there is no clear upward trend before 1980 as Fig. 54.1 below demonstrates. After 1980 the mean temperature jumps by about +0.72 °C relative to the 1961-1980 average and +0.36 °C relative to the long term trend. This means that the overall trend from 1796-2010 is +0.22 ± 0.06 °C per century. This represents only a very modest warming of less than 0.5 °C since pre-industrial times, over half of which could be accounted for by urban heating effects (see Post 14 and Post 29). The rest is within the expected limits of natural variability.
Fig. 54.1: The temperature trend for Hungary since 1780. The best fit is applied to the interval 1796-1985 and has a positive gradient of +0.08 ± 0.08 °C per century. The monthly temperature changes are defined relative to the 1981-2010 monthly averages.
The trend in Fig. 54.1 above is the result of averaging the anomalies from nineteen station records with over 480 months of data. Of these three are long stations with over 1200 months of data while the rest are medium stations. All nineteen stations have significant data after 1975 (see Fig. 54.2 below). For that reason the period 1981-2010 was chosen for calculating the monthly reference temperatures (MRTs). For a description of MRTs and their use in determining the anomalies see Post 47.
Fig. 54.2: The number of station records included each month in the mean temperature trend for Hungary when the MRT interval is 1981-2010.
The frequency distribution in Fig. 54.2 above indicates that the trend data in Fig. 54.1 after 1973 will be more reliable than the trend data before 1973. However, the trend data before 1973 is consistent with similar data from Czechoslovkia (Post 53), Germany (Post 49) and the Baltic States (Post 51). The data is also fairly evenly distributed across the country (see Fig. 54.3 below), and so its mean is likely to be representative of the overall true temperature trend for Hungary.
Fig. 54.3: The locations of long stations (large squares) and medium stations (small diamonds) in Hungary. Those stations with a high warming trend are marked in red.
Despite this, the trend shown in Fig. 54.1 is significantly different from that calculated by Berkeley Earth using adjusted data rather than the actual raw data. Averaging the adjusted data gives the trend in Fig. 54.4 below.
Fig. 54.4: Temperature trend in Hungary since 1780 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 1796-2010 and has a gradient of +0.34 ± 0.02 °C/century.
The trend based on Berkeley Earth adjusted data in Fig. 54.4 above now has a significant warming trend that is at least 50% more than is seen in the original data in Fig. 54.1. It also agrees almost exactly with the published version shown below in Fig. 54.5.
Fig. 54.5: The temperature trend for Hungary since 1750 according to Berkeley Earth.
The difference between the adjusted data and the raw data is illustrated below in Fig. 54.6. Overall it amounts to an additional warming contribution since 1840 of nearly 0.5 °C. This is more than the total warming seen in the raw data in Fig. 54.1 (about +0.47 °C).
Fig. 54.6: The contribution of Berkeley Earth (BE) adjustments to the anomaly data in Fig. 54.4 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 1841-2010 has a gradient of +0.285 ± 0.007 °C per century. The orange curve shows the contribution just from breakpoint adjustments.
Conclusions
1) The surface temperatures in Hungary were stable up until 1980. Thereafter they experienced a modest increase of between 0.36 °C and +0.72 °C that occurred abruptly around 1988 (see Fig. 54.1).
2) The warming seen in the raw data (in Fig, 54.1) is significantly less than that seen in the Berkeley Earth adjusted data (see Fig. 54.4).
3) The adjustments made to the data by Berkeley Earth (see Fig. 54.6) add more warming than is seen in the raw data (see Fig. 54.1)
4) Current temperatures, while higher than the 1795-1980 average, are actually similar to those seen in the 1790s and 1940s (see 5-year moving average in Fig. 54.1).
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