It is entirely possible, except nowhere it happened in an useful way. Where there is more rain, it tends to fall in bursts, with flooding. Because moister and hotter atmosphere is more unstable, it's basic principle in the meteorology. And the problem is, our agriculture(and not just it) can't cope with that. Proposals to compromise yields to improve land's stability/water retention are met with hostility.

No, instability in climate is caused by many factors but chief among them would be high and low pressure systems colliding with each other. Moister and warmer atmosphere is not difficult to cope with. Produce grows extremely well in the tropics and not so well in Siberia.