Background atmospheric CO₂ mixing ratios from individual flask air samples for Amsterdam Island. Only measurements satisfying the data selection criteria from background measurements are plotted. Consecutive background measurements are joined by lines. Background measurements interrupted by non-background measurements are not joined by lines.

Monthly atmospheric CO2 mixing ratios at Amsterdam Island expressed in parts per million (ppm) 
and reported in the Scripps Institution of Oceanography X93 manometric mole fraction scale.  
Annual values were calculated by CDIAC for years with complete records. Missing values are denoted by -99.99.



Year	Jan	Feb	Mar	April	May	June	July	Aug	Sept	Oct 	Nov	Dec	Ann




1982	-99.99	-99.99	338.95	338.96	338.93	339.24	339.71	339.95	339.94	339.94	339.99	339.96	-99.99
1983	340.07	340.32	340.53	340.66	340.66	340.98	341.44	341.75	341.82	341.83	341.97	341.93	341.16
1984	342.14	342.51	342.16	341.54	341.46	341.98	342.85	343.08	342.84	342.73	342.92	343.32	342.46
1985	343.40	343.31	343.59	343.70	343.62	343.79	344.13	344.56	344.75	344.85	344.89	344.85	344.12
1986	344.97	345.17	345.16	344.75	344.74	345.21	345.63	345.94	345.97	346.14	346.45	346.48	345.55
1987	346.68	346.71	346.67	346.93	347.12	347.35	347.84	348.52	349.04	349.15	349.21	349.32	347.88
1988	349.17	348.95	348.76	348.70	348.98	349.49	349.95	350.03	349.98	349.97	349.93	349.89	349.48
1989	349.97	350.17	350.19	350.01	349.87	350.26	350.76	351.00	351.15	350.94	350.96	351.22	350.54
1990	351.78	352.29	351.79	351.40	352.00	352.74	353.09	353.29	353.29	353.49	353.67	-99.99	-99.99