AP Photo

The conventional wisdom about blockbuster movie sequels is that the second acts are seldom as good as the originals. The exceptions, like The Godfather: Part II or The Empire Strikes Back, succeed because they build a bigger backstory and add dimensions to the original characters. The sudden release last week of another 5,000 emails from the Climate Research Unit (CRU) of East Anglia University​—​ground zero of “Climategate I” in 2009​—​immediately raised the question of whether this would be one of those rare exceptions or Revenge of the Nerds II. 

Before anyone had time to get very far into this vast archive, the climate campaigners were ready with their critical review: Nothing worth seeing here. Out of context!...