I would prefer that evangelicals read any of the pre-Vatican II papal encyclicals instead. At least those are readable and are not burdened by mind-numbingly opaque ambiguity.
Section 67 of Caritas in Veritate draws heavily from the pre-Vatican-II papal encyclical Pacem in Terris [1963]., and to a lesser extent the post-Vatican-II encyclical Populorum Progressio [1967]. In the section on the U.N. the "subsidiary" quote comes from BXVI himself, but the majority (but not all) of the "one-world-government" sounding quotes are taken Pope John XXIII's encyclical Pacem in Terris. I don't see any ambiguity in anything that's said.