Scientists in Belgrade came up with the idea of “planting” large tanks of water and algae in places where trees can’t grow. The tanks are 10-50x more efficient than a normal tree for the space it takes up and is in general highly sustainable, even creating excellent fertilizer in the process. You can skip about halfway through the video for the actual information about them.
For sure, and bike shares on every block. but in cities as they currently exist, it’s a good option.