By Laurence Lewis   Daily Kos

The end of April has arrived, and with it, the record for the first month in human history with an average carbon dioxide level in Earth’s atmosphere above 400 parts per million has been set.
With a little more than 24 hours left in the month, the average for April can’t slip below 400 ppm. “Every day in April has been over 400 ppm,” said Pieter Tans, a climate scientist with the National Oceanic and Atmospheric Administration.