Okay.
Very quickly—maybe we can go deeper in question time—the social costs of carbon is a way of trying to assess the damage associated with the emission of one tonne of carbon into the future for that specific year, and then discount it back to a present value today so that we can compare it with costs and benefits today.
It is widely used in cost-benefit analysis. Actually, it's the basis of regulatory impact analysis for climate action in Canada. So long as it is used, I think it requires a serious upgrade along the lines of what the National Academy of Sciences recommended in the U.S. in 2017.
It's controversial, first, because a stable climate is not a good to be traded. It's the foundation of survivable—you might say—societies, but as long as economic benefit analysis remains trendy, I think it is important to put a cost to climate damage and to do so in a transparent way that actually shows the ethical and the justice trade-offs that happen in considering these things.
Very briefly—