It is unreasonably frustrating to me that discussions of the Social Cost of Carbon by Economists are seemingly using models that read like a Libertarian's Fancy Footwork to Excuse Desired Behaviour. Basically, by deciding that we value the lives of our children and children's children less than our own comfort, we can deprecate the loss-in-value of the e.g. losing India, the Southern US, Australia, and Africa and the whole of the middle latitudes of the Earth until we find the cost of carbon to be low enough to justify continuing with business as usual.

To get an idea of how warped the SCC calculations are: current predictions for a 6 degree warming: the kind of environment that would likely involve a wholesale relocation of around 1.5 billion people due to extremes of heat making vast areas uninhabitable, the loss of the vast majority of the Earth's agricultural lands due to frequent droughts, fires, floods and excessive heat leading to widespread starvation, sea level rise likely to lead a few hundred million to further relocation, vast die-offs of flora and fauna dramatically reducing the biodiversity of the planet... the predictions for this kind of apocalyptic result for our grandchildren is that it might cost 8% of GDP. See this Economist article for a discussion of that.

But what is really galling is the discount rate. This is the rate by which the DICE models says, to paraphrase "we don't tend to care about a problem if it's in the future, so let's put in a fudge factor to say 'we'd rather have 3 cars and a cottage now than worry about our grandchildren starving in the future' so that we can tweak the social cost of carbon to any value we care to produce". So it's wonderful (Nobel Prize wonderful) in that it captures how much people would like to spend on fixing climate change... which is exactly frak-all compared to what needs to be done to avoid a catastrophe. The Trump admin used this fudge factor to declare the SCC to be $2, not enough to deter even the most ridiculous polluters.

So put me down on the "existential threats to humanity should be evaluated based on keeping the Earth habitable, not whether Bob-from-Facebook thinks its worth it because he has trouble planning for the future" camp. Oh, and if you are a rich nation, and you decide to only factor in the damage to your own nation in your SCC calculations, ignoring all the damage done to the rest of the world... well, if you can't see the immorality of that I can only assume my words will mean nothing to you.