![](https://247wallst.com/wp-content/uploads/2022/08/imageForEntry11-puu.jpg)
Source: bagi1998 / iStock via Getty Images
1998
> Carbon dioxide (CO2): 365.69 ppm
> Methane (CH4): 1,762.43 ppm
> Nitrous oxide (N2O): 314.20 ppm
![](https://247wallst.com/wp-content/uploads/2022/08/imageForEntry12-Crh.jpg)
Source: jpa1999 / iStock via Getty Images
1999
> Carbon dioxide (CO2): 367.81 ppm
> Methane (CH4): 1,772.33 ppm
> Nitrous oxide (N2O): 315.15 ppm
![](https://247wallst.com/wp-content/uploads/2018/08/gettyimages-664819-e1534527355667.jpg)
Source: Joe Raedle / Newsmakers / Getty Images
2000
> Carbon dioxide (CO2): 368.92 ppm
> Methane (CH4): 1,774.07 ppm
> Nitrous oxide (N2O): 316.14 ppm
![](https://247wallst.com/wp-content/uploads/2022/08/imageForEntry14-07c.jpg)
Source: Jupiterimages / Stockbyte via Getty Images
2001
> Carbon dioxide (CO2): 370.38 ppm
> Methane (CH4): 1,772.95 ppm
> Nitrous oxide (N2O): 316.89 ppm
2002
> Carbon dioxide (CO2): 372.49 ppm
> Methane (CH4): 1,773.14 ppm
> Nitrous oxide (N2O): 317.47 ppm