How will 'global warming' affect rainfall patterns over north-western regions of Europe?
(thanks to Keith Dancey for this answer....which is his reply to a question in the newsgroup.....)
If more heat is pumped into the system (system=earth) then more water vapour will be put into the atmosphere. How that would affect our (local) weather depends upon how it would affect the world's climate, and how the world's climate affects our (local) weather. Precise answers to these questions are not known. There are climate models which can be run, and they are improving, but they are not 100% accurate, and they may never be! Such models require knowledge of the atmosphere and oceans that are beyond us at the moment, and computing power that can represent all the processes that are going on all the time. A rather tall order. You might be interested to learn that the Gulf Stream (a natural phenomenon that defines, to a large extent, the UK's mild climate for it's latitude) might even become disrupted under certain conditions in some ocean models. So whether global warming is happening, and how far it might go, is really very important, even to us.
Global warming, per se, can be tested by measuring the average temperature of the surface of the sea, and keeping records for a long time. We have historical records, of varying accuracy and varying coverage. We now have instruments orbiting the globe that can measure the sea-surface temperature to breathtaking accuracy. The data indicates warming. The period is rather short. But we don't know (for certain) that this is because of us (human economic activity) or some natural phenomenon that we have yet to discover. Most scientists working in the field believe the former. Increased rainfall (and other local climate change) for the UK and Europe can indeed be an outcome of global warming. When a possibly chaotic system such as the world's climate is perturbed, it might be impossible to predict the outcome, other than there is going to be change. Global warming does not necessarily mean "drier". It certainly does not mean "drier everywhere". And it also does not mean "warmer everywhere".