Economics, What policies can reduce emissions?Watch
Indirect tax (for negative externality in production)
They can place excise taxes/ subsidise more efficient working firms, e.g the subsidies towards Tesla for electric cars.
Provide information e.g labelling or advertisements to inform consumers (which will, hopefully, reduce demand for CO2 producing products)
I can only think of those 2 currently, I'll add to this if something comes to mind, main intervention would be tradable pollution permits, they are the most effective.
Subsidising the study or research that help reduce the gas emissions from factories (positive externalities)