Should central banks become involved in the climate issue?

Some recent proposals aim to give central banks a role in compliance with the climate objectives and the fight against CO 2 emissions. (1) This could, for example, apply a penalty to the securities they accept as collateral when they are issued by companies that emit a lot of CO 2 . In theory, this would lead to an increase in the cost of capital and a reduction in these companies’ investments, and therefore to lower production and to a rise in the prices of products that lead to CO 2 emissions. So this is the equivalent of a carbon tax on companies according to their carbon footprint. What objections can be made against this proposal? There must be a way to properly balance the penalties imposed by the central bank to ensure that investment is not reduced too much; CO 2 emissions must be eliminated by 2060-2070, and a faster pace would raise serious adjustment problems; The increase in the returns provided by companies emitting CO 2 could attract investors seeking high returns, and increase, instead of reducing, these companies’ financial resources; These companies could borrow from new lenders that are perhaps undesirable (Chinese banks, etc.); Lastly, there must be no conflicts of objectives for monetary policy.