Not Manhattan. Outside of Central Park there's not much green space at all. Midtown south, Flatiron, Downtown, etc have nothing! They may have paved urban parks but there's simply not enough green space per person, and that's a choice they've made historically based on greed. People need accessible green space for use on a daily basis near their homes, not requiring long subway rides back uptown to Central Park.

There are many small parks in Manhattan in addition to Central Park.

The Battery Conservancy has 25 acres of parkland downtown at the tip of lower Manhattan; most of which is green.

Midtown had a bunch of small parks nestled between roads in lots of places near Columbia U.

Columbia U is pretty far uptown, not midtown. Small pocket parks don't really cut it, people need to be able to go for walks under trees and maybe a sporting field or two.

The Flatiron building is literally one block away from Madison Square Park...

I am well familiar with my old stomping ground Madison Square Park. Not what I'd call a proper park by any means. It's a series of benches around a lawn. Nice to sit and people watch, but that's about it.