Earth System Research Laboratory Carbon Cycle and Greenhouse Gases Group Continuous Insitu Measurements of CH4 at Global Background Sites, 1973-Present

NOAA/ESRL/GML operates four staffed atmospheric baseline observatories from which numerous measurements of greenhouse gases are conducted. These baseline observatories, also known as global background sites, are located in Barrow, Alaska; Mauna Loa, Hawaii; American Samoa; and South Pole, Antarctica. The measured data are baseline levels, trends, and causes of variability of atmospheric gases that have the potential to affect global climate. These observatories were established in order to provide a sampling of the most remote air on the planet so that the true "background atmosphere" could be monitored. GML first began continuous in-situ measurements of CO2 at these observatories in 1973, and added CH4 and CO measurements in the 1980's. The ongoing data set is contingent upon the baseline observatories that are still in use going forward.