A February First: CO2 Levels Pass 400 PPM Milestone

With only one day left in the month, it’s basically official: February’s average carbon dioxide level will be above 400 parts per million, a marker of how much of the greenhouse gas is accumulating in the atmosphere thanks to human emissions.

Last year, the monthly average didn’t go above the 400 parts per million (ppm) mark until April, which was the first month in human history with carbon dioxide (CO2) levels that high. Levels stayed that high for a full three months, and they are likely to stay that high for many more this year.

by Andrea Thompson, Climate Central

Full Story: http://news.discovery.com/earth/global-warming/a-february-first-co2-levels-pass-400-ppm-milestone-150227.htm