To expand on #3: the "present" in the sentence isn't even taking place before the firing squad, that's "many years later". It places the reader in a timeless moment.
I think another opener that's at least as good is "Maman died today. Or yesterday maybe, I don't know" (even though this is misleading w/o the whole context..)
As much as I like Camus's The Stranger, and am not familiar with Marquez, I still agree with coldtea. In a single opening line (when you know nothing of the rest of the book), Marquez places a beginning (seeing ice) an ending (the firing squad), and makes you want to read more to see what happens in between.
Merely goes for the surprise element.
The other quote also:
1) gives more plot information (the hero is an older man, sentenced to death),
2) beautifully evokes his nostalgia before death (remembering an event from his childhood)
3) AND builds suspense: He is at the moment in front of the firing squad. Will he die? Get a pardon? Somehow be resqued?