Re: Could a large solar shade in space alter earth's weather patterns?

If you block off part of the sunshine to Earth you can indeed change the
weather and the climate. It is not known which blocking you would have to
perform to achieve which results, though. But that could be studied with
climate models.

One practical problem - apart from launching a 100x100 mile object! - is
the political issues that would follow from diverting rain to arid regions.
Who would be missing out on that rain, and could you prove that noone
missed out before you started?

A similar problem arose when people tried to make artificial rain by
'seeding' clouds. You can indeed make some clouds start raining with that
technique, but seeding companies got into legal trouble because farmers
downwind said "Hey! That was my rain! I will sue you now!". Countries might
do the same thing, or start wars, if they felt they were missing out on rain
that was due.