Re: Venus did harbor water... but it was boiled away as its surface temp rose to 470 deg
The only thing that makes it habitable for most of these people is air conditioning (and opulent salaries, obviously). At the beginning of the 20th century, only 25 000 people found Quatar habitable enough to live there, whereas today the population is at 2.5 million, a 100-fold increase. I've been to Dubai in summer and everything seemed to be geared towards eliminating any exposure to outside air, with people shuttling in air-conditioned cars from their air-conditioned houses to their air-conditioned parking spots underneath their air-conditioned offices. Now I know that sounds a lot like what many people in the West are doing, but in the Gulf they take it to a whole new level - even their bus stops are all air-conditioned, and before the global recession put an end to the worst excesses, there were serious plans to create a refrigerated beach in Dubai. Yes, seriously.
You're right that a few degrees warmer won't make much difference to the air conditioners, though.