Winter 2019-2020 has so far been very unpredictable and unusual. Most of the time in the whole of SEAmBOTH area the weather has been very mild and rainy. Hailuoto island in the middle of January is one of the northernmost snowless places on the planet – only some fjords in western Norway lack snow higher up north.
Usually this time of year the whole northern Bothnian Bay is frozen solid – only navigational ship ways are kept open with ice breakers. This year the ice barely covers the shores and we don’t need icebreakers. The annual winter ice road to Hailuoto island (about 8 km long) seems like a distant dream right now when the temperatures soar around 0-3 C. The longest ice road in Finland, Hailuoto ice road is 10 km long and is usually open to regular cars between February and April. Even though the winters might be getting milder and the ice road disappearing because of that, it would soon be history even without the climate change – building of Hailuoto bridge will start 2020.
With the advancing climate change, extreme weather conditions, like winters 2019-2020, will become more frequent. Global warming doesn’t mean that every winter would be snowless and iceless like this year, but it means that we’ll get winters like this more often in the north as well.
This year will be difficult for Bothnian Bay ringed seals, which normally give birth to their pups on ice. This spring they will most likely have to raise their pups on land, which is what the other Baltic Sea seal species, grey seal, usually does. The difference is that ringed seals are adapted to pup on ice, and their future doesn’t look too bright right now.
During the past hundred years, the Bothnian Bay has apparently not frozen solid on only two other occasions – at some point in the 1930s and in 2014-2015. This year might get to the statistics as the third in a century, unless the temperatures start dropping soon. And the fact is that Baltic Sea ice is disappearing as the climate gets warmer and the sea warms up.
Other than denying ringed seals their breeding ice, lack of ice affects the nature in many other ecological ways as well. If we don’t get a thick layer of ice, the spring ice erosion and scraping, which keeps some of the shallow shores without vegetation and so helps vascular plants which are poor competitors, will not happen. Also, thick ice that reaches the shallow bottoms in bays and near shores, yanks plants and sometimes seeds from the bottom and helps them migrate, frozen in the ice. There are myriad of algae and plankton living in the sea ice, or rather in the tiny tube-like salt water canals inside the ice, and quite a surprising amount of species under the ice as well. If the sea lacks the ice, then a complete nature type (sea ice) is lost for that year, and we have pelagic habitat instead. And we don’t get to go ice fishing.
The next few weeks will show if we’ll get any kind of sea ice this year, or if the sea ice habitat will be replaced by a pelagic habitat this year.