English: This graph shows the annual percentage growth rates in radiative forcing for six major types of long-lived trace gases in Earth's atmosphere. Growth is based on direct measurement of these gases by NOAA since 1979.
The major gas types are:
- CO2: Carbon Dioxide
- CH4: Methane
- N20: Nitrous Oxide
- CFCs: Chlorofluorocarbons (mainly CFC-11 and CFC12. Also included under this grouping are CCl4, CH3CCl3, and Halons which are also ozone-depleting chemical and contributed 5% of the group's forcing in 2020)
- HCFCs: Hydrochlorofluorocarbons (HCFC-22, HCFC-141b, and HCFC-142b)
- HFCs: Hydrofluorocarbons (HFC-134a, HFC-23, HFC-125, HFC-143a, HFC-32, HFC-152a, HFC-227ea, and HFC-365mfc. Also included is SF6 which contributed 13% of the group's forcing in 2020)
- Total: includes all of the above groups
Thousands of halogenated gases have been manufactured for refrigeration and other industrial purposes, and many others are possible. These groupings fairly capture the influence of the major ones as of year 2020. Like SF6, gases such as CF4, C2F6, NF3, and SO2F2 fall outside these grouping and are also being monitored by NOAA and others.
Growth rates are directly calculated from annual forcing data published by NOAA, using the following formula:
Percent GrowthN = 100 x ( RFN - RFN-1 ) / RFN-1, where N=year.
Radiate forcing (RF) data are inferred from direct measurements of the atmospheric concentration of individual gases, as gathered from multiple sites around the globe.
Reference:
- Butler, J.H. and S.A. Montzka (2013-08-01) THE NOAA ANNUAL GREENHOUSE GAS INDEX (AGGI) - Updated Spring 2021[1], NOAA/ESRL Global Monitoring Laboratory