Climate scientists sometimes analyze “extreme events,” like storms, floods, or droughts, and try to determine whether such extreme events were partially caused by climate change or not. The standard method for doing this analysis is called the “risk-based” method. It carries the risk of underestimating the role of global climate change in extreme events and missing connections that are really there; this practice thus underestimate society’s risk of socially-significant damages, to both physical and psychological well-being. A new, “storyline,” method has recently been proposed and proved controversial. It is meant to be applied when the conditions needed for the risk-based method are lacking. The storyline method is like an autopsy: it gives an account of the causes of the extreme event—the flood or storm—and can indicate whether climate change was one of these causes. It carries the risk of false alarms, or of overstating the role of climate change, a risk that we contend has rarely been actualized.
Proponents of each account are concerned about different risks. On my analysis with Naomi Oreskes, the two approaches are complementary, and the resistance to the storyline approach to evaluating extreme events and climate change has arisen from undue conservatism and an under-appreciation of how much scientific methods can and do change over time. We advocate more discussion of the societal risks of extreme events; the choice of method should depend on which risk is more worrisome in the case at hand.