Core sediments retrieved by three icebreaker and drill ships revise what is known about the Arctic since about 55 million years ago. For a few million years, the North Pole felt downright Floridian thanks to the presence of greenhouse gases released by some unknown geologic process. The warmth as recorded by the core data is 10 degrees Celsius higher than climate models had predicted. They suggest that heat–trapping gases may exert a more potent climatic influence than previously thought.

North Pole's mean annual temperature: 20 degrees C

Temperature 55 million years ago: 23 degrees C

Concentration of atmospheric carbon dioxide today, in parts per million: 380

Concentration 55 million years ago: 2,000

Rise in average global temperature as a result: 5 degrees C

When “icehouse” conditions began: 45 million years ago