Pliocene epoch featured greenhouse gas levels similar to today's but with higher average temperatures
The Arctic wasn’t always frozen tundra. About 3.6 million years ago, the far north was blanketed in boreal forests, and summers were 8 degrees Celsius warmer than they are today, geologists report May 9 in Science.
Researchers pieced together that picture from sediments buried beneath Lake El’gygytgyn (pronounced EL-gih-git-gin), about 100 kilometers north of the Arctic Circle in northeastern Russia (SN: 11/20/10, p. 13). The sediments preserve the most complete history of Arctic climate on land over the last 3.6 million years.