Of course, they never got back to Earth with the gold. Global warming has caused seas to rise so that NYC is underwater to a large extent. Buildings still stand above the water line but the bases are submerged. People travel via boat, like Venice, only run down. Not far away there are areas with high walls and dry land behind them, so it's the poor who live in the flooded areas, eeking an existence.
Tara is an orphan who won a place in the family of wealthy stars via their reality TV show "The Ark". It's a clear reference to Brad Pitt and Angolina Jolie's adoption of orphans from around the world, and I suppose other celebrities like Madonna, too. Thrown into it is the whole reality TV nonsense to emphasize the vacuous of both reality TV and celebrity cultures, with their obvious overlap.