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.
Carbon capture is something we need. Except for real. Which will probably involve algae tanks orders of magnitude larger than this, and then tossing harvested algae down a mineshaft, never to be seen again.
As for these tanks, nah. As public art, they’re not great, and their stated benefits are limited.