Tsunamis
Maybe they could have big turbines that allow them to move so they can get out of the way.
tide changes
Above solution might work.
shark attacks
dafuq
just so many things could go wrong
Prototypes that would lead to improvisation.
The issue here is that you can't feed all these people and create enough power for them. Not to mention the issue of job competition, disease, clean water, pollution, etc.
Well more land would result in more greenhouses/power plants/laboratories and that would give people jobs while possibly fixing food, power and diesase problems.
The others I dunno
Honestly I dunno if this would work, I just thought it might help somehow. :s