How can one make an arctic winter and how can one prove it? The first condition for an interesting climate experiment is to exclude the sun. We did it by concentrating research on the winter period during the 1st and the 2nd war winters of WWII. The second condition for improving experimental conditions is to exclude the external influence of the water influx coming from different sources, e.g. the Atlantic Ocean. The Baltic Sea is almost completely disconnected from the oceanic system, salinity is low or inexistent (Gulf of Bothnia) and the current system affected only by local forces (wind, temperature, salinity, and influx of river water). For the completion of an excellent climate change, the third condition is easy to imagine: the forceful stirring and shaking of the water basin. This all happened between June and December 1941 and the following winter proved the effectiveness of the experiment. Northern Europe fell pray to a record icy winter.