New York 2140 by Kim Stanley Robinson

In the not-so-distant future the oceans of the world rose and mankind had to make a few changes. But life, even in the face of massive ecological changes, goes on much as it has. In New York City (the so-called “Super Venice”), boats may have replaced taxis and the skyscrapers of Manhattan may have become island-enclaves sitting amidst the drowned streets of the city, but life goes on…until everything changes.

The mysterious disappearance of two coders from the farm-floor the Met Life Tower sparks a series of events that will spell massive changes to New York and the wider world beyond. Changes with the potential to be more devastating than the both the massive floods of the last century combined.