The early arrival of winter has led to a considerably higher area of Estonia's coast icebound, while around 80,000 square kilometers of the Baltic Sea as a whole, or quarter of its total area, is now covered with ice.
Rivo Uiboupin, director of Tallinn University of Technology's (TalTech) institute of marine systems, said that: "The first cold spell, which started in late November, served to cool down the seawater temperature."
The next cold snap, which started with the turn of the year, led to a spreading and thickening of the ice, while the current cold weather, practically a continuation of the cold snap in early January, which was punctuated by a few days of milder weather, will intensify the effect, Uibopin said.
Estonia's coastal waters are quite shallow and in addition to two large cargo vessels recently coming to grief in the ice, the services of an icebreaker are regularly required, to enable navigation.
The Väinameri, an area of sea encircled by Saaremaa, Hiiumaa, several other islands plus the mainland, has already frozen over.
Martin Kaarjärv, ice-breaking coordinator at the Transport Administration (Transpordiamet), said that ice began to form in Pärnu Bay from late November.
Since then, Estonian icebreaker EVA-316 has come to the assistance of ships over 32 times.
"We started at the beginning of December. For a time when it was milder then it was a little less, but now there is ice in Pärnu Bay extending 20 miles, all the way to Kihnu," Kaarjärv said.
Rivo Uiboupin said that in general, winters in future are set to be milder, with severe ones such as 2023-2024 so far, more the exception.
While larger ships initially did not require the services of the EVA-316, now all vessels need assistance.
Martin Kaarjärv at the Transport Administration said that in fact no vessels barring passenger ferries which serve Estonia's islands can pass through the straits to reach the Väinameri.
In recent years, there have been some ice-free winters, while several years ago a level of ice cover comparable with the current extent was not seen until February or march.
Further away from Estonia, all countries with Northern Baltic coastlines, i.e. Finland, Sweden and Russia, are using ice-breakers; the Swedes have five such vessels and the Finns a total of seven, Kaajärv said.
Editor: Andrew Whyte, Mirjam Mäekivi