One of the more interesting (to me at least) aspects of the warming trend of both the atmosphere and the oceans is that for each degree C increase in the mean atmospheric temperature increases its water carrying capacity on the order of 4.2 quadrillion kilograms. Rising ocean temperatures, combined with rising air temperatures are increasing the rate of evaporation of sea water into the air.

The effect of this is transporting more water in the air over longer distances. This "side effect" of global warming will likely make all of our past observations of precipitation rates in any given region completely moot. It also makes suspect any extrapolation of current precipitation trends into the future.

My reading of the current literature suggests to me that we might have an opposite problem, which is massive flooding in areas on a regular basis where previously they considered such floods "100 year" or "1000 year" storms.

What every climate scientist I have talked with agrees with, is that the current climate is being destabilized relative to historical records. Thus extrapolations become more and more uncertain (have larger error bars) as the initial conditions drift further and further away from anything on record.