You can't keep your alarmist claims straight. There will be more water from the melting ice. Precipitation patterns will change but that doesn't mean there won't be a net increase in water. Sea levels are going to rise but we aren't going to get more water? Come on this is absurd.
Ok, sure, *liquid* water will see a net increase as currently solid water becomes liquid, mostly serving to increase saltwater volume, which is useless. The bigger consequence is how that more cycling through the evaporation/precipitation cycle will manifest, and it would suck if it's mostly moving water through the air to the ocean. Wouldn't be too terrible if it were the other way around, unless it's mostly in unworkably strong hurricanes. The key thing is we aren't sure.
The additional energy is heat. That heat will be plenty useful for planting crops where it was previously too cold. We already see a northward migration of life.
At best, this moves the viable agriculture land. As *maybe* new farmland would open up (hardly a safe bet), existing farm land would be made non viable. When you say "energy" I assumed you meant like hydrocarbon or electricity, which obviously won't be aided. So yes, more thermal energy, but hardly an assurance that would mean a net increase in arable land.
Plants can grow bigger and faster with additional CO2 we've already seen the earth get greener as its been warming up. You're denying observed reality and science. CO2 supplementation is an existing plant growth booster. You just don't like the truth.
I seriously doubt you have anything suggesting that we've had more successful agricultural thanks to atmospheric CO2 concentration shifts.
Why wouldn't it be comforting? CO2 isn't the reason we hadn't invented civilization. It's likely humans hadn't even evolved yet which says absolutely nothing about the issue. This is strange thinking that does not follow.
Because we know the score for the current climate and how we can house and feed ourselves. We've got very little to go on to confidently know the specifics of change. It would be foolish to assume we know, and since we are currently reasonably "good" with how things are, there's a lot more room for downside than upside. Like say I told you I'm going to rip you out of your nice house and plop you randomly somewhere on Earth to fend for yourself. Would you take that bet that you'll end up somewhere nicer than your house?