During that ancient time, known as the mid-Pliocene epoch, temperatures were higher by about 2 to 4 degrees Celsius (3.6 to 7.2 degrees Fahrenheit) and sea levels were higher by roughly 20 meters (almost 66 feet) than today, explained Kevin D. Burke, lead author of the study and a researcher and Ph.D. candidate at the Nelson Institute for Environmental Studies at the University of Wisconsin-Madison.