Background atmospheric CO₂ mixing ratios from individual flask air samples for Alert, Northwest Territories, Canada. Only measurements satisfying the data selection criteria fro 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 Alert, Northwest Territories, Canada 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




1985	-99.99	-99.99	-99.99	-99.99	-99.99	350.01	343.77	337.71	338.98	342.77	345.54	348.83	-99.99
1986	351.20	351.97	352.58	352.95	353.10	351.24	345.55	340.18	339.78	344.28	347.82	349.57	348.35
1987	350.88	352.22	353.34	353.86	354.06	352.71	347.76	341.60	341.68	346.29	350.17	352.46	349.75
1988	354.27	355.46	356.47	357.28	357.22	355.17	349.91	344.56	345.38	350.20	353.85	355.71	352.96
1989	357.63	359.19	360.00	359.46	358.95	357.55	351.81	345.73	346.46	350.64	355.46	358.93	355.15
1990	359.46	359.65	360.48	360.67	360.21	357.18	350.87	346.18	346.63	351.25	355.74	358.13	355.54
1991	360.32	361.28	361.37	361.63	361.41	359.75	353.80	347.67	348.11	352.61	357.18	361.13	357.19
1992	362.58	362.59	363.14	362.85	362.69	361.31	353.96	346.90	347.51	352.06	356.23	359.77	357.63
1993	361.15	361.56	362.56	363.22	363.28	360.47	353.34	348.22	348.78	353.16	356.97	359.99	357.73