Earlier this year I found this tiny pine leaf near Lake Michigan, and for reason, it had caused the snow around it to melt. I sat there for a few minutes wondering how, and why, and then I felt my extremities getting numb by the cold. So I decided to take a picture and I walked away.
Probably something to do with the organic oils of the pine reducing the freezing point of water??
-but that removes the mystery ;)
Possibly. The pine oils are really volatile.