Convert SOC change and greenhouse gas fluxes to CO2 equivalents

Converts soil organic carbon (SOC) stock change and CH4/N2O fluxes to CO2-equivalent emissions using 100-year GWP values.

Usage

to_co2e(delta_soc = 0, ch4 = 0, n2o = 0, gwp = c("AR6", "AR5", "AR4"))

Arguments

delta_soc: Numeric. Change in soil organic carbon as mass of elemental carbon (C). Positive values indicate soil carbon gain; negative values indicate loss.
ch4: Numeric. Methane emissions as mass of CH4.
n2o: Numeric. Nitrous oxide emissions as mass of N2O.
gwp: Character. IPCC report containing GWP100 values used: "AR6", "AR5", or "AR4".

Value

Numeric. Total CO2-equivalent emissions as mass of CO2e, expressed on the same spatial and temporal basis as the inputs.

Details

Inputs may use any mass units, but must be converted to consistent units and expressed on the same spatial and temporal basis before summing. Equations:

CO2e_SOC = -ΔSOC * (44 / 12)

CO2e_i = m_i * GWP100_i

GWP values:

- Default GWP100 values are from AR6 (IPCC, 2021). - For CARB inventories, use "AR4" for comparability with current CARB inventories (CARB, 2025).

References

IPCC (2021). Climate Change 2021: The Physical Science Basis (WG1 AR6). Cambridge University Press. https://doi.org/10.1017/9781009157896

IPCC (2006). 2006 Guidelines for National Greenhouse Gas Inventories. IGES, Japan.

IPCC (2019). 2019 Refinement to the 2006 IPCC Guidelines. IPCC, Switzerland.

Greenhouse Gas Protocol (2024). Global Warming Potential Values. WRI/WBCSD. https://ghgprotocol.org/global-warming-potential-values

California Air Resources Board (CARB), 2025. Greenhouse Gas Global Warming Potentials. https://ww2.arb.ca.gov/ghg-gwps

Examples

to_co2e(delta_soc = 1)
#> [1] -3.666667
to_co2e(ch4 = 1)
#> [1] 29.8
to_co2e(n2o = 1)
#> [1] 273
# return total over all sources
to_co2e(delta_soc = 1, ch4 = 0.1, n2o = 0.01)
#> [1] 2.043333