CO2 since 1800

The 2018 figure is the average of seasonally-adjusted figures for June and July, 2018 (which is a good projection for the annual average). Previous years are annual averages.

We also have a similar graph for methane (CH4),
and a combined graph with both CO2 and CH4.

Direct measurements of CO2 at Mauna Loa Observatory, in Hawaii began in March, 1958. This is the annual average data we’ve graphed: (1959–2017)
For monthly data see:

1850-1958 data is from (ice cores).

1800-1850 CO2 data is from (Law Dome ice cores, 75 year smoothed).