Mauna Loa Observatory
[3] MLO has been part of the National Oceanic and Atmospheric Administration (NOAA) Global Monitoring Laboratory (GML)'s Baseline Observatory network since 1972.
The observatory's location, far from continental sources of emissions and above the marine inversion layer, makes it an ideal site for atmospheric monitoring.
[4] The observatory's reading of a historic high in its daily recording of carbon dioxide emissions—400 parts per million, in 2015—was referenced by Pope Francis in his apostolic exhortation on the climate crisis, Laudate Deum.
The Mauna Loa Solar Observatory and National Science Foundation's Global Oscillations Network Group station share this site.
The northern trailhead to the summit of Mauna Loa is located below the observatory site and is managed by Hawaiʻi Volcanoes National Park.
2 concentrations as measured at MLO