It is likely that global quantities of precipitation will tend to increase over the next 100 years due to the increase in evaporation - in overall terms, this will lead to more moisture in the atmosphere. But there are differences at regional level: at higher latitudes, we can expect a general increase in the amounts of precipitation (not necessarily in the summer!), but it is also possible that they will decrease in the sub-tropical zones. Apart from whether a particular region will become wetter or dryer, there is also a risk that seasonal fluctuations and extreme events will increase. These extreme events include periods of drought or intensive heavy precipitation.