Niestacjonarność przebiegu temperatury powietrza nad obszarem Europy – zmiana reżimu termicznego w Europie w latach 1987–1989 i jej przyczyny

The study discusses changes in the average annual air temperature over Europe in the years 1931–2020. The results of the research show that in 1987–1989, there was a sudden change in the thermal regime over Europe and a discontinuity appeared in the course of this climatic element. In the years 1931–1988, despite the high inter-annual variability, the temperature trend was zero. A positive, statistically significant, temperature trend appeared after 1988. The entire warming in Europe, which can be estimated at ~2.3 deg, occurred after 1988. The discontinuity in the course was caused by an abrupt change in macro-circulation conditions in the Atlantic-Eurasian circulation sector, which manifests itself as a fundamental change in the frequency of the macrotypes of the mid-tropospheric circulation (500 hPa) according to the Wangengejm-Girs classification, causing an equally fundamental change in the weather structure. The change in macro-circulation conditions was forced by a change in the thermal state of the North Atlantic – a sharp increase in the intensity of oceanic heat transport to the north. The analysis showed that the annual variability of temperature over Europe was mainly influenced by natural processes, the variability of which explains ~65% of its variance. Radiative forcing, which is a function of anthropogenic increase in CO2 concentration in the atmosphere, explains only 7–8% of the variability of the average annual temperature over Europe, being a secondary or tertiary factor in shaping its changes.