How can we find out how the weather used to be?
From 1862 there is a permanent record of temperatures and rainfall measurements in Røros. This was the time when Lars Thurmann started the systematic measurement of temperature and precipitation at selected times on a daily basis.
He had a simple system where he described the weather as: clear, cloudy, snowing, raining, sleet or blowing. From 1871 weather measurements were taken over by the Norwegian Meteorological Institute in Oslo, but measurements were recorded by local people. Initially the weather instruments were placed on the magistrates property, then they were placed in the care of the apothecary Nielsen and, after some time, the station master at the railway took over the work. By examining these records we can see how the weather has been over the past 150 years.
But how do we learn about the climatic conditions, the weather and the winds in Røros, from long, long ago? There are many examples of changes for the worse in weather conditions in the Røros community’s history which researchers have found in the study of the annular rings of old trees. Rings that are close together indicate slow growth of the tree in poor weather conditions. The climate from long ago can also be measured by the presence of pollen in the ground. It is possible to find out the age of the various types of pollen. From this we can deduce whether or not a certain type of pollen was produced, and, if not, then this would indicate that conditions were too extreme for the plant to propagate itself.