Charlene states that microbes become less active when A REGION's temperature drops below normal.
Olaf then explains that microbes found in the Arctic and microbes found in the subtropics, i.e. microbes from very cold places and very hot places, ate oil at nearly the same rate.
However, Charlene's point is that microbes become less active when their region's specific temperature drops below normal. Normal is subjective for each region. Very cold temperatures are normal for the Arctic and very hot temperatures are normal for the subtropics.
Thus, Olaf is misinterpreting Charlene's use of the word "normal."
Hope that clears things up! Please let us know if you have any other questions.
