Endangered Languages, by Evangelia Adamou, is part of the MIT Press Essential Knowledge series, so it's essentially an introduction, a bit of a primer on what it means for a language to be endangered, what we might do about it, etc. As a Welsh person (who doesn't speak Welsh), obviously I have a bit of a vested interest here: Welsh is the least endangered of the Celtic languages, but it isn't for lack of trying on the part of our English rulers (see also: the Welsh Not, Brad y Llyfrau Gleision, etc).

Welsh is a bit too successful for Adamou to spend much time on here, despite all that, though I think the revival efforts probably deserved a bit of a mention alongside the revival efforts for Breton, Cornish and Irish, including stuff like the Welsh Language Acts. To compare how Welsh is doing compared to other more endangered languages is pretty instructive -- but there's a limited amount of space in any one book, of course.

In the end, discussing endangered languages and how to protect them is surprisingly similar to discussing conservation, though of course it's best not to stretch the similarity too far. I was interested to read about the fact that languages should be considered "dormant" rather than "extinct" now: I don't know if I think that's a nice way to look at it, or perhaps one which softens the tragedy of losing all native speakers of a language a little too much.

Anyway, an interesting introduction.