2010
2013
2015
2018
1.62
3.1
2.9
.9
123 million tons
286 billion tons
4.4 trillion
246 billion tons
2 inches
10 inches
14 inches
8 inches
Nitrogen oxide
Water vapor
Carbon dixode
Methane
All of the above
1 million tons
7 million tons
13 million tons
2 billion tons
400 parts per million
100 parts per million
900 parts per million
10 parts per million
100%
78%
95%
83%
1 to 2
3 to 5
2.5 to 10
5.3 to 11.2