Climate indicators are different measures that are used to show changes or to illustrate complex phenomena in a simple way. Sometimes climate indicators are warning signals. The indicators can be used in a broader context, such as for comparison with indicators from other countries or from other climate analyses.
They can also be used to study changes over time and space. The common measures are yearly, seasonal or monthly values for different parameters that describe the climate. It is very important that the indicators used are homogenous (uniform and comparable) over time and preferably also in space.
Indicators for the climate demand access to long time series, since the changes are often relatively slow and the background noise (the natural variation) is significant.
As a first step, SMHI has developed the following indicators:Annual temperature deviation for Sweden
(since 1860)Annual precipitation for Sweden
(since 1860)Extreme precipitation
(since 1930)Geostrophic wind in Sweden
(since 1901)Changes in sea level in Sweden
(since 1886)Length of vegetation period
(since 1961)Global radiation in Sweden
(since 1983)Maximal ice extent
The indicators can be analysed and input into a broader context of analyses of covariance of indicators, comparisons with indicators from other countries, and with descriptions of large-scale flow patterns and their variation/change over time. Comparisons can also be made with the results from the models that have been developed to describe the climate system.