The disappearance of ice cover on temperate lakes (Central Europe) as a result of climate warming.

This paper presents changes in the ice regime of lakes located in the northern part of Poland. It has been established that in the period 1960–2019, there was a successive decline in the ice extent of lakes, clearly visible in individual parameters; formation of ice cover is delayed by 3.0 days/decade (on average for all lakes), its decline occurred earlier by 3.8 days/decade, and the length of ice cover is shorter by 6.8 days/decade. Moreover, the maximum thickness of the ice cover is becoming thinner, and this process has progressed at an average rate of 2.3 cm/decade. The aforementioned situation shows strong relations with air temperature. It was particularly evident in the late 1980s, when a change in the thermal regime took place, which was documented in most of the analysed parameters, as demonstrated in the study. It has been established that from that period up to now, the decline of ice cover tends to start 19 days earlier, the duration of ice cover is shorter by 22 days, and the ice cover is 8 cm thinner, on average. The observed transformation affects the imbalance of the existing equilibrium in lakes, which can be related to both biotic and abiotic processes. [ABSTRACT FROM AUTHOR]