Comment on “Can We Name Earth’s Species Before They Go Extinct?”

species are disappearing before being described. We suggest that their conclusion is overly optimistic because of a limited selection and interpretation of available evidence that tends to overestimate rates of species description and underestimate the number of species on Earth and their current extinction rate. In an attempt to draw attention to the chal-lenge of describing and monitoring Earth’sbiodiversity in the face of looming environ-mental crises, it has been frequently claimed that many species are likely going extinct before being named (1–5). Costello and colleagues (6) chal-lenged this view and suggested that such a worry “result[s] from overestimates of how many spe-cies may exist, beliefs that the expertise to describe species is decreasing, and alarmist estimates of extinction rates. ” We suggest that their con-clusions are overly optimistic because of a lim-ited selection and interpretation of the availabl