Influence of climate change on the ice conditions of the Curonian Lagoon

Abstract

Summary: The Curonian Lagoon is a shallow freshwater lagoon of significant environmental value in the south-eastern part of the Baltic Sea. The objective of the study was to evaluate changes of ice indices (duration, thickness and breakup dates) of this lagoon and to assess their possible tendencies in the 21st century. A methodology was developed combining the assessment of past changes (1960–2017) of ice indices and their projections in the near (2021–2040) and far (2081–2100) future periods using a hydrometeorological database, statistical methods and regression analysis as well as regional climate models and RCP scenarios. Climate change has a considerable impact on ice conditions in the Curonian Lagoon. During the historical period of 1960–2017, the Curonian Lagoon was covered with ice for 72 days a year, ice thickness reached 23 cm, whereas ice breakup was observed in the middle of March on average. According to the different scenarios, in the near and far future periods, ice duration will last 35–45 and 3–34 days, respectively. Ice thickness is projected to be 13–15 cm in the near future, whereas, at the end of the century, it is expected to decline to 0–13 cm. In the past, the lagoon ice cover remained until the middle of the third decade of February. At the end of the 21st century, RCP8.5 scenario projects the most drastic shifts: the permanent ice cover might be absent, whereas short-term ice cover is expected to melt already in the beginning of January. Keywords: Curonian lagoon, Ice indices, Ice duration, Ice thickness, Ice breakup, RCP scenarios