Create a multiplayer game, and there should be a button saying "Load game". Of course, since it only supports multiplayer autosaves, it presents you with them. Determine which is the latest. The save game file itself includes the date and turn number, but I can't remember in which order. Turns first, year second, I think.
Oh and do keep in mind that in a multiplayer game you load you have to have all the available human player slots taken so you can begin. Even if one player is missing you can't continue a saved game. It's stupid that an AI cannot take the slots place, but such it is.