How would you keep the Outback green? I'm no climate scientist, but I've wondered why it is the way it is. Is it due to the lack of a mountain range on the Australian west coast, so the air doesn't get pushed up to cool?
Edit I forgot in this imagined world we have 'free' energy, so you can just pump water in.
I can't find a link, but there's a theory (and I don't know if it's been discredited), but once again, because humans settled into Australia they displaced mega-fauna and generally ruined the ecosystem in Australia and the Outback now is what it is. Even today, there's a story doing the rounds about how free roaming bison in the US double the plant biodiversity of the plains just by trampling on stuff.
Edit I forgot in this imagined world we have 'free' energy, so you can just pump water in.