Greenhouse gas
Carbon dioxide in the atomsphere
320
325
330
335
340
345
350
355
360
365
370
375
380
385
390
395
400
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
2014
2016
Co2 ppm: 400.5
Co2 ppm: 400.5
When measuring gases like carbon dioxide, oxygen, or methane, the term concentration is used to describe the amount of gas by volume in the air.