A First: 400 ppm Happened Last Week; Wilder Weather on Its Way
Lee Van Ham
Wednesday, May 15 400 (ppm) parts per million carbon dioxide in the atmosphere hasn’t happened in at least 3 million years. That was back during the geological era known as Pliocene, long before Homo sapiens had evolved on the planet. Earth was a number of degrees warmer during the Pliocene than it is at this moment; sea levels may have been as much as 80 feet higher. But on May 9 (2013), scientists in the Mauna Loa Laboratory in Hawaii, the benchmark-establishing lab, measured 400 ppm according to the Los Angeles Times.




