Carbon’s social cost can’t be retrofitted to water

In our view, assessing the “social cost of water” is unrealistic (see J. Rockström et al. Nature 615, 794–797; 2023) because it risks oversimplifying a range of complex water issues. The social value of water varies across space, time and cultures, so it is not “akin to” the social cost of carbon, the global economic costs resulting from emitting one extra tonne of carbon dioxide, which is consistent across different contexts and countries. Such a flawed, catch-all concept could result in policies and investments that target the wrong challenges.