“The record from the Vostok core shows that CO2 levels and temperatures have varied in tandem. Current CO2 levels are unprecedented in the last 420,000 years. Credit: J.R. Petit et al, Nature, vol. 399 (1999).” — Elizabeth Kolbert Copy Share Image
“at 378 parts per million, current CO2 levels are unprecedented in recent geological history. (The previous high, of 299 parts per million, was reached around 325,000 years ago). It is believed that the last time carbon dioxide levels were comparable… — Elizabeth Kolbert Copy Share Image
