This post refers to my analysis of recorded annual mean temperature trends at 16 stations located in large cities in Europe. The stations were all with long records (mostly over 100 years) and located in large cities (mostly with populations over a million). The analysis used raw data (as recorded, without any adjustments) as published by KNMI (the Dutch Meteorological Institute). Polynomial curves of best fit were added to the plots.
Normally data from stations located in cities are not suitable for general studies of climate trends (except within urban areas!), because of the uncertain effects of urbanisation on the temperatures. However, city data are often longer than rural data, and it is interesting to compare their long-term trends. It is generally considered that urban temperatures have risen considerably during the past half-century due to increased development (roads, buildings, airports, etc) and increased air pollution (due to industrialisation and vehicles). The urbanisation effect may vary considerably in different cities; for example, if a station is located near a coast there may be minimal urbanisation effect. Another uncertainty with urban stations is that their locations may have changed over the years. Also, prior to the introduction of Stevenson screens in the late 19th century, the instrumentation was different and this will also affect the apparent long-term temperature trends.
This selection of 16 European cities is part of a larger analysis involving 50 cities, worldwide.
Plots are shown below for the 16 European stations. It should be noted that the polynomial fit line (in red) can sometimes be misleading at either end of the series as the line is very dependent on the temperature values in individual years (this sensitivity does not occur away from the start and end of the series).
[ Dublin temperatures show a cyclical trend with Highs around 1850 and 1970, with a Low around 1910. The temperatures have been fairly constant for the past 40 years (since about 1945). ]
[ Lisbon temperatures have been increasing steadily at a rate of about 1.5 degC/century since 1900. There is no evidence of increasing temperature trend in recent decades. ]
[ Marseille temperatures were essentially constant until about 1960. After 1960 the temperatures have increased by about 1.3 degC. ]
[ Zurich temperatures show a cyclical trend with Highs around 1850, 1930 and 2010(?) and Lows around 1890 and 1970. The present-day temperatures are about 0.9 degC higher than in about 1930. ]
[ Copenhagen temperatures have increased steadily since about 1860 at an average rate of about 1.2 degC/century. There is no evidence of increasing temperature trend in recent decades. ]
[ Berlin temperatures show a cyclical trend with Highs around 1780(?), 1900 and 2010(?) and Lows around 1820 and 1960. The present-day temperatures are about the same as was recorded around 1870 and 1920. ]
[ The Warsaw temperature trend was rising from about 1800 to about 1900, was essentially constant until about 1980 and has been rising since then. The present-day temperatures are about 1.0 degC higher than around 1980. ]
[ Prague temperatures show a cyclical trend. However, there is a sudden drop in temperature of about 1.5 degC during the period of missing data between 1940 and 1950 which may indicate a change in station location and exposure. ]
[ Vienna temperatures were essentially constant until about 1960, but have increased by about 1.5 degC since then. ]
[ Athens temperatures show a well-defined cyclical trend, with Highs in about 1870, 1940 and 2010(?) and Lows in about 1890 and 1980. The present-day temperatures are about 0.7 degC higher than in about 1940. ]
[ Bucharest temperatures show a cyclical trend, with Highs around 1860(?), 1950 and 2010(?), and Lows around 1890 and 1990. The present-day temperatures are about the same as that recorded in around 1950. ]
[ Odessa temperatures were essentially constant prior to about 1990, after which they have increased by about 1.5 degC. ]
[ Kiev temperatures were essentially constant prior to about 1940. The temperatures then increased slightly until about 1990 and at a faster rate since then. The present-day temperatures are about 1.5 degC higher than they were around 1980. ]
St Petersburg 1744-2016
[ The St Petersburg temperature trend was essentially constant prior to about 1860, after which ity increased by about 1.0 degC until 1940. The trend was constant again until about 1980, when the temperatures trend increased. The present-day temperatures are about 1.5 degC higher than in around 1980. ]
[ Moscow temperatures were badly incomplete prior to 1881. Since then temperatures have increased until around 1980, when the trend increased. The present-day temperatures are about 1.5 degC higher than in about 1980. ]
[ Kazan temperatures increased at a rate of about 1.2 degC/century until around 1920. Temperatures were then essentially constant until around 1980. Present-day temperatures are about 2.0 degC higher than around 1980. ]
Please let me know what you think of my analyses. firstname.lastname@example.org