Which has a greater impact on the survival of an organism, temperatures above its maximum temperature or temperatures below its minimum temperature?

A temperature above its maximum temperature tolerance it has the most impact over the organism survival. When under higher temperatures than the ones supported by the organism, the organism's proteins tend to denature and it becomes impossible to return to normal activity. While when under lower temperatures then the ones normally supported, the organism may stop its activity but can easily return to it once the temperature returns to ideal.