The Past Is Red by Catherynne M. Valente

Catherynne M. Valente, the bestselling and award-winning creator of Space Opera and The Girl Who Circumnavigated Fairyland returns with The Past is Red, the enchanting, dark, funny, angry story of a girl who made two terrible mistakes: she told the truth and she dared to love the world.
The future is blue. Endless blue…except for a few small places that float across the hot, drowned world left behind by long-gone fossil fuel-guzzlers. One of those patches is a magical place called Garbagetown.

Tetley Abednego is the most beloved girl in Garbagetown, but she’s the only one who knows it. She’s the only one who knows a lot of things: that Garbagetown is the most wonderful place in the world, that it’s full of hope, that you can love someone and 66% hate them all at the same time.

But Earth is a terrible mess, hope is a fragile thing, and a lot of people are very angry with her. Then Tetley discovers a new friend, a terrible secret, and more to her world than she ever expected.