Climate change The great lakes of southern Finland may not freeze in the coming decades – “A winter in the south like last year gives a pretty good picture of what lies ahead,” says the professor.

“Our grandchildren will not see the same ice winter as we do,” says Timo Huttula, professor of hydrology, docent and non-fiction writer.

In the future For decades, the ice of the large lakes in southern Finland may not be completely frozen in some years. The reason for this is climate change.

“Definitely ice can not come at all. If you think of the large lakes in Southern Finland, such as Lake Lohjanjärvi, it is a rather large and deep southern lake. Therefore, it is very likely that there will be years when it does not freeze at all, ”says professor of water science, ie hydrology, docent and non-fiction writer. Timo Huttula To STT.

A similar future is predicted by the Development Manager of the Finnish Environment Institute Johanna Korhonen.

“Over the last 20 years, the freezing of lake waters has been further delayed and the ice has melted even earlier.”

Finland the freezing of lake waters has been studied for a long time, so the changes are easy to observe. According to Huttula, there is statistical information about the delay in freezing several decades ago. For example, Kuopio’s Kallavesi has been studied since the 1830s. At the beginning of the statistics, the lake froze as early as the end of November, but now the freezing has stretched closer to Christmas.

“There are similar developments in these other large lakes. Freezing on Lake Oulujärvi has been delayed by about ten days from the mid-19th century to the present day, ”he says.

The freezing of Finnish lake waters has been studied for a long time, so it is easy to observe the changes. There are statistical data on the delay in freezing several decades ago.­

He estimates that in this century the effects will be visible in southern Finland and will reach as far as Oulu. In the lakes of Lapland, the change is hardly reflected in the same way.

In old statistics, the freezing of a lake is probably defined as the fact that the lake has formed a uniform ice cover. A uniform ice cover means that the entire visible water area is covered with ice, allowing the thickness of the ice to be measured and reported.

Wholly without ice, however, the lakes of Southern Finland will hardly remain. Small lakes tend to freeze faster and easier than large ones. This is because large lakes are large heat reservoirs that take time to cool.

“It is important to remember that we also have small lakes in southern Finland that freeze faster than large lakes. So you can still find ice fishing and touring skating places in them, ”says Huttula.

Climate change will also increase windiness in winter, which is also important for ice development.

“Winds can break weak ice,” he says.

According to Huttula, a wind similar to that during the Liisa storm would be enough to make a few centimeters of ice cover break.

Lake water global warming is behind climate change. In addition to rising water temperatures, the future of lakes depends on how the load on agriculture and forestry can be limited.

“Improving the ecological status and development of lakes is a time at the mercy of controlling the nutrient and humus loads in the catchment areas,” says Huttula.

Another positive factor would be to limit the rise in air temperature, as the warming of a large lake follows the average temperature of the air. If the rise in air temperature is brought to a halt, then the fate of the lakes will be better.

Even if the rise in temperature is now brought to a halt, its effects will still be visible for decades to come. The winter in southern Finland was snowless and rainy last year, and the same may be expected in the coming years.

“Our grandchildren will not see the same ice winter as we do. A winter in the south like last year gives a pretty good picture of what lies ahead, ”says Huttula.

With climate change, the lake waters of the south are likely to freeze for an increasingly shorter period of time. Pictured is a child and a dog on the shores of Lake Bodominjärvi in ​​Espoo on November 22, 2020.­


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