It's not easy being green
I don't have much to comment about the idea for green roofs, except that I think it's brilliant. You can find some research regarding green roofs here.
Now where are the green roof detractors? This article finds some drawbacks.
Check out the links to the Chicago City Hall--just beautiful. Much better than tar. Imagine Cleveland with fields of green on top of its buildings. Cool. Where do we sign up?