For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
A very useful book on this subject is 'Frozen in Time, by Michael Oard, a veteran meteorologist.
Warm oceans can be accounted for by tectonic activity - sub-oceanic vulcanicity and rapid plate movements. Snow and ice built up in mid-latitudes as the evaporated waters were cooled by continental breezes, creating a snow-blitz. Once there was snow cover on land the sun's rays would be reflected further reducing temperatures. Volcanic ash also had this effect.
The post-Flood Ice Age model has much to commend it. Secular science has dozens of attempted explanations of an Ice Age (or many ice ages), but none are completely satisfactory.