Well, trees are one of them. More money means more trees planted.

Or that money could be invested in renewable energy, which will reduce emissions in other areas.

And when you increase the cost of something, you get less of it, so taxing emissions should mean fewer emissions.

And so on.

not real ones, most of them are scams where countries accept money in order to not deforest areas they werent going to anyway, double dip, or just deforest regardless