“New CO2 Milestone: 3 Months Above 400 PPM”
April fell first. It lasted through May. Now June will be the third month in a row with average carbon dioxide levels above 400 parts per million.
Atmospheric concentrations of the greenhouse gas, which helps drive global warming, haven’t been this high in somewhere between 800,000 and 15 million years.
The rate of increase of the CO2 level is more worrying than the record outright volume.