Air temperature changes until now

Changes in air temperature in Toruń in Central Poland have been analyzed for the period 1871-2010 (5). Over this 140-year study period, a sizeable and statistically significant increase of 0.1 °C per decade was found in the air temperature in Toruń. The greatest increases occurred for spring and winter, at 0.12 and 0.11 °C per decade, respectively. A lesser warming was recorded for autumn (0.10 °C/10 years), and particularly for summer (0.07 °C/10 years). The air temperature trends are statistically significant for all seasons. In the period of 1871-2010, winters shortened markedly (by 7%) and summers lengthened by 3.8%. These results are in close agreement with the findings of analogous studies of the same for other areas of Poland and Central Europe (5).

Similar trends were found for in Poznań, also in Central Poland. For the years 1848-2016, the air temperature grew at a rate of 1.1 °C per 100 years. Strongest increase was observed in winter (+ 1.5 °C/100 years) and lowest in summer (+ 0.6 °C/100 years) (7). These seasonal differences have also been observed for other parts of Central Europe, including Potsdam, Prague, Warsaw, Cracow, Toruń, Wrocław, and Łódź (5,7,8). In the last 30 years, the warming trend for Poznań increased to a rate of + 4.6 °C per 100 years, with the highest values recorded for summer (+ 7.5 °C/100 years) (7).

Heat wave and cold wave changes until now

In the Carpathian Region (encompassing Croatia, Hungary, Slovakia, Czech Republic, Poland, Ukraine, Romania and Serbia), heat wave events have become more frequent, longer, more severe and intense over the period 1961 - 2010, in particular in summer in the Hungarian Plain and in Southern Romania (8). Cold wave frequency, average duration, severity, and intensity over this period, on the other hand, generally decreased in every season except autumn. In this study, a heat wave was defined as at least five consecutive days with daily maximum temperature above the long-term 90th percentile of daily maximum temperatures. Similarly, a cold wave was defined as at least five consecutive days with daily minimum temperatures below the long-term 10th percentile of daily minimum temperatures (8).

The trend analysis shows a general tendency to more frequent, longer, more severe and more intense heat wave events in every season in the entire Carpathian Region. On the other hand, the cold waves show a general tendency to less frequent, shorter, less severe, and less intense events (8).

The Carpathian Region and the Mediterranean area are the two European hotspots showing a drought frequency, duration, and severity increase in the past decades and in particular from 1990 onwards (2). When drought effects are exacerbated by heat waves or vice versa, such combination may cause devastating effects, as it happened in summer 2003 in Central Europe (3).

Precipitation changes until now

Observed changes in extreme precipitation between 1961-1990 and 1991-2015 are statistically insignificant (4). However, in the period 1989–2018 compared with 1959–1988 the frequency of very extreme precipitation events (the 1% highest daily precipitation amounts) has increased (9).

In the period 1951-2013, summer precipitation total seems to be stable; neither trends nor even weak tendencies in time series of total summer precipitation were detected around Poland. In this period there are clear visible increases in winter precipitation totals in the northwest and west areas; at some stations these increases are statistically significant (at the 0.05 level). For the East and Southeast, no changes in winter precipitation totals are observed. In general, an increase in the share of winter precipitation within the annual sum is observed (6).

References

The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Poland.

1. Spinoni et al. (2015)
2. Spinoni et al. (2013), in: Spinoni et al. (2015)
3. Fink et al. (2004); Ciais et al. (2005), both in: Spinoni et al. (2015)
4. Pińskwar et al. (2019)
5. Pospieszyńska and Przybylak (2019)
6. Szwed (2019)
7. Kolendowicz et al. (2019)
8. Wibig et al. (2004), in: Kolendowicz et al. (2019)
9. Pińskwar (2022)