一亿年前，极地平均35度C

Extreme global warming of Cretaceous period punctuated with significant global cooling -- ScienceDaily
https://www.sciencedaily.com/releases/2015/05/150528083818.htm

Scientists have reconstructed the climatic development of the Arctic Ocean during the Cretaceous period, 145 to 66 million years ago. At that time the poles were devoid of ice and average temperatures of up to 35 degrees Celsius prevailed in the oceans. Yet new research shows there was a severe cold snap during the geological age known for its extreme greenhouse climate.