Questions for the 20th century (Historiography)

The 20th century-a world historical epoch? Where do the caesura fall, where are the axes of meaning? Will the epoch from 1914-1945 endure as the paradigmatic age of catastrophe? Why did the period of catastrophes come to an end in the early 50s-at least in Western Europe? Were de-colonisation and the establishment of new states not more important in world history than the cold war? Was it an "American century"? The weight of personalities? The 20th century-a succession of failed efforts to check capitalism? What was really new about the 20th century? Nothing but farewells? What can we discern from the quick trip through the dense forest of historical questions?