Future could bring more storms, floods, and bugs to Helsinki
VTT evaluates impact of climate change on Finnish capital
In the heaviest of storms, the sea water in the Gulf of Finland might rise as high as three metres from the present level. This means that placing sandbags at Helsinki’s Market Square might not be enough of a measure to protect the valuable old buildings in the centre of Helsinki.
In January 2005 many of those buildings were threatened by rising water, even though it had risen no more than a metre and a half above normal. At the end of the century, the rise could be twice as great.
This is one of the worst-case scenarios set forth in a study by the Technical Research Centre of Finland (VTT), which examined the implications of climate change for Helsinki in 2070-2100.
“These are extreme situations, but preparations have to be made for them”, says researcher Irmeli Wahlgren.
The prospect of elevated sea levels has already been taken into account for some time in the planning of new areas in Helsinki.
The city’s old drainage system would be challenged if the amount of rain increases significantly from now. Annual rainfall is expected to increase by about one sixth from the present level.
In addition, heavier storms are also expected.
Reijo Hyvönen of the Finish Meteorological Institute says that maximum wind speeds at the Harmaja Lighthouse in a 50-year cycle have been just under 26 metres a second. VTT is predicting that in extreme cases, maximum wind speeds could reach 30 metres a second, more than 100 km/hour.
However, there will be less shivering during the winter, with temperatures dropping to about -17° Celsius, while the overall minimum temperature is currently about -31°C.
Once in 50 years the temperature is considered likely to drop to a minimum of -27°C. Currently the minimum in a 50-year cycle is set at -43°C.
Winter activities will have to revolve around pastimes that do not require ice and snow. The period of snow cover could decrease by as much as 70 days. The period of ice cover on the sea is likely to be reduced by 120 days, lasting as little as perhaps three weeks.
“The fauna might take a turn toward the more unpleasant”, says Hannu Airola of the Uusimaa Environment Centre.
He warns that so far the cold winters have kept the number of insects that feed on agricultural plants under control. For instance, Colorado potato beetles could find it easier to wreak havoc on the potato harvest.
The average annual temperature is set to rise by an estimated four degrees Celsius in Helsinki. Year-round average temperatures in Kaisaniemi have varied between 3.3 and 7.1°C.
Hot and dry phases are expected to focus on the May-August growing season, which means that even the little rain that does come would be likely to evaporate quickly.
This means that fir trees, with their root systems near the surface, will lose ground to pine and birch, with their deeper roots.