... which ends the same way as taxation treaties. Foreign countries will happily introduce CO2 emission regulations, then lie about them on a large scale.
See for example China: who have signed plenty of environmental treaties yet are dumping nuclear waste in the oceans on a large scale. Hell, China isn't even protecting their own people or nature just to avoid transporting the waste to the ocean. Rivers can do that for free, you see. To fully demonstrate how governments work, they lie about doing this (despite the fact it can be very easily measured), and secondly they criticize other countries for doing much less (such as China now criticizing Japan being forced into dumping some Fukushima cooling water)
The other alternative is what most tax havens are doing. They are raising taxes on companies ... and handing out subsidies that, somewhat suspiciously, exactly balance the tax raise. This is even done within Europe. This principle can easily be applied to emission regulations. After all, it's always paying to be allowed to pollute. Governments can simply pay that back some other way.