The research team set out to study Lake El’gygytgyn, “Lake E” for short, which was formed 3.6 million years ago when a meteorite hit earth. Because it has not been eroded by continental ice sheets, which is rare in the Arctic, it has an undisturbed sediment record that the team wanted to examine. The sediment samples examined were collected in 2009 from Lake E, and enabled the scientists to look back in time 2.2 to 3.6 million years ago.
The research team discovered that “[e]vidence from Lake El’gygytgyn, NE Arctic Russia, shows that 3.6-3.4 million years ago, summer temperatures were ~8°C warmer than today when pCO2 was ~400 ppm,” the article summary explains. Essentially, the summer temperatures were about 14 degrees warmer than current temperatures in the Arctic, significant because of the relatively small difference.