Monthly average carbon dioxide (CO2) levels have reached above 420 parts per million (ppm) for the first time on record.
https://www.independent.co.uk/climate-change/news/carbon-dioxide-record-co2-b2072614.html# decimal monthly de-season #days st.dev unc. of
# date average alized of days mon mean
1958 3 1958.2027 315.70 314.43 -1 -9.99 -0.99
1972 5 1972.3716 330.07 327.14 -1 -9.99 -0.99
1986 5 1986.3750 350.52 347.42 18 0.31 0.14
2002 4 2002.2917 375.19 372.54 29 0.55 0.19
2009 5 2009.3750 390.36 387.24 30 0.51 0.18
2013 5 2013.3750 400.02 396.64 28 0.37 0.13
2016 3 2016.2083 405.06 403.54 28 0.81 0.29
2018 4 2018.2917 410.45 407.65 21 0.90 0.38
2021 1 2021.0417 415.52 415.16 29 0.44 0.16
2020 4 2020.2917 416.45 413.70 28 0.66 0.24
2020 5 2020.3750 417.31 413.82 27 0.61 0.23
2021 6 2021.4583 418.94 416.51 28 0.65 0.23 (so after 419 was hit)
2021 4 2021.2917 419.05 416.30 24 1.12 0.44
2022 4 2022.2917 420.23 417.48 28 0.91 0.33
https://gml.noaa.gov/webdata/ccgg/trends/co2/co2_mm_mlo.txt