This dataset shows global atmospheric CO₂ trends (marine surface, monthly average).As mentioned by the source, "the uncertainty in the global monthly mean is estimated using a monte carlo technique that computes 200 globally averaged time series, each time using a slightly different set of measurement records from the NOAA GML cooperative air sampling network. The reported uncertainty is the mean of the standard deviations for each monthly mean using this technique. CO₂ expressed as a mole fraction in dry air, micromol/ mol, abbreviated as ppm."Data originally from NOAA - Global Monitoring Laboratory.