New Yorker: This past Thursday, the daily average atmospheric concentration of carbon dioxide, as measured by the Mauna Loa observatory in Hawaii, passed four hundred parts per million. In some way it was a meaningless milestone. We know that CO2 is increasing; we knew this moment would come; we know that four hundred is no more different from three hundred and ninety-nine than it is from four hundred and one.
Still, the number should shake us, if not shock us. We`ve got more carbon dioxide in the atmosphere...