Before anything else: this is an incredibly racist book. Specifically anti-black racism. It isn't about racism, it's just written from an undeniably racist perspective. The racism adds literally nothing to the book, it's just plain cruel and inexcusable, even for the 60's. There are other CWs, but the racism is so atrocious that it needs to be in the reviews. 

That said, I think the rest of the book is some of the best climate fiction I've ever read. This book lives or dies based on how much you enjoy Ballard's prose, and I think it's phenomenal. This is the best drowned-city or drowned-world book I've read so far, and it makes immediate sense why it's a classic in the genre.