Atmospheric Carbon Dioxide Record from Mauna Loa

The Mauna Loa atmospheric CO2 measurements constitute the longest continuous record of atmospheric CO2 concentrations available in the world. The Mauna Loa site is considered one of the most favorable locations for measuring undisturbed air because possible local influences of vegetation or human activities on atmospheric CO2 concentrations are minimal and any influences from volcanic vents may be excluded from the records. The methods and equipment used to obtain these measurements have remained essentially unchanged during the 51-year monitoring program. Because of the favorable site location, continuous monitoring, and careful selection and scrutiny of the data, the Mauna Loa record is considered to be a precise record and a reliable indicator of the regional trend in the concentrations of atmospheric CO2 in the middle layers of the troposphere. On the basis of flask samples collected at Mauna Loa, and analyzed by SIO, the annual average of the fitted concentrations of CO2 rose from 315.98 ppmv in 1959 to 385.34 ppmv in 2008. This represents an average annual growth rate of 1.4 ppmv per year in the in situ values at Mauna Loa.