Interpreting Customisable maps
Maps show the spatial pattern of projected change at a particular probability level and variable. Looking at the map below, it must be remembered that this map shows a uniform 80% probability level across the whole country. In reality, the 80% probability level will not necessarily occur at the same time across the whole country. So in this map, the 4°–5° change in London will not necessarily occur at the same time as the 3°–4° change in Scotland. So, maps are useful for a visual image of projected change but should not be used as spatial comparisons of change.
Also, see this FAQ on why one should never download a single map.