However, any of the main components may be of crucial importance for a country, more or less independently of the level of the other components. It is then relevant to use an averaging method that reflects this limited substitutability between components, either by a quadratic average of the components or by a reversed geometric average (as discussed in Guillaumont 2009a,b). The progressive shocks cover those due to the sea level rise and the trend in average rainfall and temperature. For each of these four main components, an exposure index (marked on Figure 8.1 in italics) and a shocks index have been computed.