“At the time, polar temperatures were 3-5 degrees C (37-41 degrees F) higher than today....”
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Whoa hoss — a difference of 5 degrees C is equivalent to a difference of 9 degrees F.
He is absolutely correct. 3 degrees C =5 degrees F (add 32F) and voila 37 degrees F.
I will leave the 9+32 degrees F for you to calculate.