While keeping crop quality? I don't think so.
Who said anything about quality? Feed the poor hungry civilians the crappy crops, they shouldn't be picky. I should know, when my family didn't have enough money to support ourselves, we literally ate out of the dumpster.
Yeah what about a lack of rain? And how many more farms would we need to feed another 2 billion people?
Lack of rain would pose a problem but we could filter the ocean water into greenhouses which will be used for the crops. Then, through transpiration, the water will then go back into rivers, lakes, ponds, or the ocean. The amount of farms needed would have to depend on how many crops they produce.