Rather stupid idea
Regardless of which side of the fence you sit regarding the climate change thing, the whole idea of "trading" pollution is an idea worthy of a Dr. Strangelove skit. It's an idea of such obscene lunacy that only human beings and politicians could come up with it. How giving money to someone in a deal that then allows you to pollute to your hearts content, in some way helps the planet, I have absolutely no idea. How does moving money about (which, let's face it, isn't even a tangible "thing" - it's just a concept - an idea) in any way mitigate the effects of pollution? Of course, it doesn't!
What it DOES do though is allow governments around the world to largely ignore and do nothing about the real environmental problems that we have. Because doing something that is actually useful and realistic would require real effort, and nobody can really be bothered with that. And it's ok if we kill the planet and we all die from a multitude of environmental catastrophes, as long as some us get rich in the meantime :-) Yep - it makes perfect sense to me!