Annual Carbon Dioxide Minimum is Now Above 400 ppm

Ice core records show that until the Industrial Revolution atmospheric CO2 levels remained fairly steady at around 280 ppm (parts per million). By 1961, CO2 data collected at a monitoring station at the summit of Hawaii volcano showed that atmospheric CO2 levels were rising steadily by about 2 ppm per year. In 2005 the station read more Annual Carbon Dioxide Minimum is Now Above 400 ppm