<Snipped quote by Kho>
The monsters, not so much, but crops are basically now non-existent. If the humans don't freeze, they will starve.
Humans are not yet wholly agricultural. They're still very much dependent on hunting animals, and those animals which are herbivores will always find shrubs here or there which survive the winter.
Edit: I'll end the darkness in a second. With your permission, @Rtron?