A Farmer, Worried About His Fruit Trees Suffering Frost Damage $4 ^ { \circ }$

Short Answer

A farmer, worried about his fruit trees suffering frost damage, calls the weather service for temperature information. He is told that temperatures will be decreasing approximately $4 ^ { \circ }$ every hour for the next 4 hours. What signed number represents the total change in temperature expected over the next 4 hours? ________ $^ { \circ }$