What is a climate indicator?
A climate indicator presents a parameter which is followed for a long period of time. It can be for example mean temperature, the length of the vegetation period, global radiation and days with snow coverage.
Many of our climate indicators are presented as deviations from the reference norm period 1961-1990. This is not the latest norm period, but when it comes to long-term climate studies the international recommendation is to keep using 1961-1990 as a reference.
How are they used?
The climate indicators can be used as study material about how the climate is changing, or to explain phenomenon’s connected to climate change. They can also be used to make complex phenomenon clearer and in certain cases as a warning signal. The indicators can be used in a broader perspective such as comparisons with other countries indicators or climate analysis. Comparisons can also be made with the results from models which describe the climate system.
Statistics clearly shows that the climate is changing. On the respective climate indicator pages, we disclose the statistics and comment on the results. We will also explain how the climate indicator is defined and how it has been calculated.
How are the indicators developed?
It is important the the indicators used are homogenous. This means they should be uniform and comparable over time, and preferably also in space. Thus, the observations should be collected from the same places through out the whole time series. When it comes to climate indicators, there are many requirements when it comes to access to long series, as the change is a relatively slow process and the natural variation can be large. The data in SMHI’s climate indicators come from a large number of meteorological, hydrological and oceanographic stations across Sweden.