What Is the Social Cost of Carbon? Is it just a concept, or does it have an actual dollar amount tagged on it?  

"Economists and advocacy groups have posited a broad range of potential pricing levels—from a few dollars to well over $100 per metric ton"

As the need for implementing sustainable solutions becomes more pressing, some Industries have experimented with an Internal price of carbon to assist decision making.

https://www.mckinsey.com/business-functions/strategy-and-corporate-finance/our-insights/the-state-of-internal-carbon-pricing