Biggest Climate News of the Year: CO2 Levels Hit 400 PPM It’s official. ย Carbon dioxide (CO2) levels around the world have passed the 400 parts per million (PPM) mark. The last time greenhouse gases were this high was roughly 4 million years ago. For millions of years earth’s natural balancing act was able to regulate the amount of CO2 in the atmosphere. However, things starting sliding south with the Industrial Revolution. […] Industry News Robin Azer | September 30, 2016 0 Comments