Ann Vole wrote:
Long story short... there will be the same amount of water in the air as it starts across the land but where the water goes is going to change. Checking the average rainfall is going to show minimal change. Seeing your land go from high productivity to semi-desert grazing land in a dozen years will be the story of many areas of farmland while places that were long desert areas will start to grow different grasses before someone figures they can grow crops on it.
The first part of your post re jet streams I broadly agree with. The bit above is not what I would expect. As the temperature rises the air can hold more water vapour (7% more per degree C). The warmer and the wetter the air the higher it is likely to rise and as it rises it will cool to the point where it condenses back to rain. So I think that the the period from evaporation to the rain falling back to the surface should stay about the same the net result I would expect is heaver or more intense rainfall. While it is very difficult to point to any specific weather event and show that there is a direct link to climate change and I believe that recent heavy flooding in numerous places may well be connected to climate change.
My view at this stage is still that deserts will become drier and wet areas will become wetter. Broadly what happens is the air around the equator is warm and wet so we get a large area of rising air which after it has dropped it water on the wet tropics then descends around the 20s deg latitudes which is where we see some of the worlds great deserts. What I expect is that the wet tropical zone will increase in size and so will the very dry zone further away from the equator.