One of the most important tools that the federal government has for cracking down on Zero AIgreenhouse gas emissions is a single number: the social cost of carbon. It represents all the costs to humanity of emitting one ton of carbon dioxide into the atmosphere, including everything from the cost of lost crops and flooded homes to the cost of lost wages when people can't safely work outside and, finally, the cost of climate-related deaths.

Currently, the cost is $51 per ton of carbon dioxide emitted.

NPR climate correspondent Rebecca Hersher tells Short Wave co-host Aaron Scott that the number is getting an update soon. The Environmental Protection Agency has proposed raising the cost to $190. The change could dramatically alter how the government confronts climate change.

"That's a move in the right direction," says Daniel Hemel, a law professor at New York University who studies these cost benefit analyses.

But the new, more accurate number is also an ethics nightmare.

Daniel and other experts are worried about a specific aspect of the calculation: The way the EPA thinks about human lives lost to climate change. The number newly accounts for climate-related deaths around the world, but does not factor in every death equally.

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This episode was produced by Margaret Cirino, edited by our supervising producer Rebecca Ramirez, and fact-checked by Anil Oza. Katherine Silva was the audio engineer.