The Earth was hotter than it is today.
The history of earth’s climate is characterized by change. Times of glaciation on the earth have been followed by warm intervals and the duration in years of both cold and warm intervals has varied by several orders of magnitude.
By the middle of the Cretaceous period about 100 million years ago, the mean- temperature on the planet's surface was between 6 and 12 degrees higher than it is today. The annual mean temperature in the Arctic was about 10 degrees, which is about 20 degrees warmer than today. In the tropical regions, the surface water temperature was approx. 5 to 10 degrees higher than the present.