My understanding is that in US, they used Emissions Credits, and this allowed a 'market' for those credits. This was more palatable to the segment of the country that are against regulations of any kind. But once there is a market, then it is ok.

There are some good points to an emissions market, it does allow accountants and corporations to determine a 'cost' that can be used in budgeting, and they can then us that as justification to purchase equipment. And it does allow the shifting of the 'cost' to the worst polluting plants. So in some ways markets are good, they steer the allocation of funds. The anarcho-capitalist types just need to understand that capitalism can be guided in this way, we know it works.