The disappearance of languages

From The New Yorker: " Linguists acknowledge that the data are inexact, but by the end of this century perhaps as many as 50 percent of the world's languages will, at best, exist only in archives and on recordings. According to the calculations of the Catalogue of Endangered Languages (ELCat) — a joint effort of linguists at the University of Hawaii, Manoa, and at the University of Eastern Michigan — nearly 30 language families have disappeared since 1960. If the historical rate of loss is averaged, a language dies about every four months."