Effect of climate warming on a change in thermal and ice conditions in the largest lake in Poland – Lake Śniardwy

Abstract

Lake Śniardwy is the largest among more than 7000 Polish lakes. So far, it has not been a subject of detailed investigations concerning long-term changes in water temperature or ice regime. A considerable change in thermal and ice conditions has been observed in the period 1972–2019. Mean annual water temperature increased by 0.44°C dec−1 on average, and was higher than an increase in air temperature (0.33°C dec−1). In the monthly cycle, the most dynamic changes occurred in April (0.77°C dec−1). In the case of ice cover, it appeared increasingly later (5.3 days dec−1), and disappeared earlier (3.0 days dec−1). The thickness of ice cover also decreased (2.4 cm dec−1). Statistical analysis by means of a Pettitt test showed that the critical moment for the transformations of the thermal and ice regime was the end of the 1980’s. In addition to the obvious relations with air temperature for both characteristics, it was evidenced that the occurrence of ice cover depended on wind speed and snow cover. The recorded changes in the case of Lake Śniardwy are considered unfavourable, and their consequences will affect the course of physical, chemical, and biological processes in the largest lake in Poland.

Temperature and ice regimes of waterbodies under impacts of global warming and a hydropower plant

“…4). This result differs somewhat from that obtained by Ptak et al (2020) for a Polish lake. The main reason is the difference between lake and river conditions.…”

“…This increase depends on the specific region and the period of observation. Studies of the water temperature of Lake Śniardwy (Northern Poland), carried out during 1972-2019, have shown a positive trend of mean water temperature of 0.44°C per decade, with the maximum increase in April of 0.77°C per decade (Ptak et al 2020). In that study, the trend of water temperature rise was greater than the increase of air temperature.…”

“…Nowadays, changes caused by global warming, are the most popular issue. Considering the longterm observations, many authors (Austin, Colman 2007;Adrian et al 2009;Strutynska, Grebin 2010;Litvinov, Zakonnova 2012;Filatov et al 2014;Woolway et al 2017;Czernecki, Ptak 2018;Ptak et al 2020) state that there is an increasing trend in water temperature. This increase depends on the specific region and the period of observation.…”

“…The freezing of waterbodies starts later, while the ice breakup starts earlier than in the previous decades. A study (Ptak et al 2020) found that over the past fifty years the ice cover duration has been decreasing at a rate of 8.7 days per decade. A trend toward reduced maximum ice cover thickness was determined as well.…”

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

“…The temperature change that occurred in the 1980s is the main factor forcing the cascade of rapid environmental changes (Reid et al, 2016). The interdependence of the impact of the processes taking place is visible, among other things, in the change of the thermal regime of lakes in this part of Europe (Ptak et al, 2020). Changes in the ice cover of the lakes result in wide consequences for the functioning of these ecosystems.…”