Marianne chose to visit New York at the worst time, weeks before a political breakdown between the US and her World which result in the third revolution and nuclear war. If you live in Utopia, don't leave! 
The book is the first in a trilogy but could be read as a stand alone. I assume the following books will expand on what happened on Earth since the story was told through Marianne, who was dealing with her own shit with the End Of The World as a backdrop.