60-to-50 million years ago (60-50 Ma) Earth’s surface temperatures averaged 10-to-15 degrees Celsius higher than present. Reduced temperature disparities between equatorial and high latitudes meant Tropical Regions were mildly warmer than now; while Polar Regions were qualitatively hotter. Azolla ferns graced lakes near the North Pole. Alligators slid into steamy swamps across Alaskan everglades. Zephyrs fluttered palm leaves aside searing Swedish shores.