2. Methodology
[5] Here “change” indicates the difference between the future 20-year climate period of 2080–2099 and a present day climate period minimally affected by greenhouse gas (GHG) forcing (1960–1979). As will be discussed later, the particular choice of these periods does not affect the basic conclusions of this paper. As a measure of temperature interannual variability we use the interannual standard deviation (σT) calculated for the selected 20-year periods. As a measure of precipitation variability we use the coefficient of variation (i.e., the standard deviation divided by the mean, here denoted as σP), which removes the dependency of the precipitation standard deviation on the mean. Both σT and σP are calculated after de-trending the data over the 20-year periods to obtain unbiased estimates of variability [Räisänen, 2002].