Have to disagree there, Rayman, I thought it was wonderful. Plenty of familiar faces (to British viewers) among the leading players (wasn't the lead scientist the guy from "Sunset Beach" and did I see David Dukes popping up in a subordinate role - haven't seen him since Stargate Atlantis
)
Anyway, back on topic - if we assume the scenario of an explosion in 1933 or 1934, then the climatic impact is just as severe with a worldwide fall in temperature leading to a mini or perhaps more than mini glaciation. Deaths in the millions though fewer than if it happened now or 100 years in the future.
In Europe, authoritarian leaders such as Hitler and Mussolini fare little better than democratic heads of state when confronted with a climatic disaster on this scale. The almost defunct League of Nations is powerless to help and with little serious air capability, such evacuations as take place are organised by ship with people from Scandinavia and Britain fleeing south in search of warmer weather.
By 1940, most order has collapsed north of the Mediterranean with warlords ruling what remains of society. In Africa, the colonies are now the homes of the displaced British, French and Italian Governments with the British Government now based in Lagos and the French in Yaounde. Tension between Italy and Ethiopia runs high. Elsewhere, Soviet civilisation has collapsed while the Chinese Nationalist Government has fled to Canton. Across India, the failed monsoon leads to famine.
Only with the return of warmer conditions in the 1980s does civilisation return slowly to the north...