There was no data-driven test of whether CO 2 from human activity alters the frequency or severity of bad weather. The report’s text repeatedly invokes “the consensus” and the sharp rise in attribution studies that seek to connect weather extremes to climate change. The presumption is that CO 2 has worsened weather, and researchers only need to determine by how much. Notwithstanding this and mountains of other evidence contradicting doomsayers, Chapter 5 of the report tries to quantify damages from “climate change,” even discussing legal applications. Hurrell noted that this is the first NAS effort to both attribute extremes to climate change and assign dollar damages.