At the end of March, the Philadelphia Orchestra premiered “Vespers of the Blessed Earth,” the most recent work of Pulitzer Prize-winning composer John Luther Adams. Critics have described “Vespers” as a marked, climate change-inspired departure from Adams’ previous compositions — ”direct and message-driven”; a score that “mourns and damns, and declares where in the past Adams might have simply observed.” But Adams is surprised that reception to “Vespers” has invoked so much politics.