New Scientist: Atmospheric scientist Ralph Keeling explains the importance of measuring a CO2 concentration of 400 parts per million at the observatory his father set up
The Mauna Loa Observatory in Hawaii has reportedly recorded a carbon dioxide concentration there of 400 parts per million for the first time. How significant is that?
It's a psychological milestone. Every year in the last few decades, CO2 concentrations have been going up by about 2 ppm per year. Those changes go unnoticed but people pay...