Table 2.
The social cost ($USD) per animal unit month (AUM) of methane (CH4), nitrous oxide (N2O), and carbon (CO2e) arising from the enteric fermentation and manure deposition of cattle on rangelands
| N2O and CH4 | GWP-20 | GWP-100 | IPCC default | |
|---|---|---|---|---|
| Methane emission—fermentation | $28.68 | $40.57 | $16.04 | $7.66 |
| Methane emission—manure deposition | $2.62 | $0.88 | $0.35 | $0.29 |
| Subtotal social cost CH4 emission/AUM | $31.30 | $41.45 | $16.39 | $7.95 |
| N2O emission—manure | $4.20 | $3.19 | $3.55 | $3.55 |
| Total social cost/AUM | $35.50 | $44.64 | $19.93 | $11.49 |
The N2O–CH4 costs are based upon the social cost of N2O and CH4 while GWP-20, GWP-100, and IPCC defaults are based upon the social cost of carbon (CO2e). Data are based upon values determined at a 3% discount rate which is $1500/metric ton for CH4, $18,000/metric ton for N20, and $51 per metric ton for CO2e (Interagency Working Group on Social Cost of Greenhouse Gases, United States Government 2021). Calculations of the social costs reported in this text use the N2O and CH4 costs