Such as this CO2 measurement, made from a dedicated instrument for the last ~8 years: https://ocov2.jpl.nasa.gov/science/ https://ocov2.jpl.nasa.gov/science/ I

Such as this CO2 measurement, made from a dedicated instrument for the last ~8 years: https://ocov2.jpl.nasa.gov/science/ https://ocov2.jpl.nasa.gov/science/ It uses broadly the same technique as in OP -- spectroscopy to detect the absorption of sunlight from the presence of that particular chemical species. Because the above instrument was designed for the purpose, it's much more accurate and able to distinguish small variations in CO2, not "just" large plumes.