Greenhouse-Gases

Greenhouse-gas radiative forcing budget for the well-mixed industrial-era GHGs plus tropospheric ozone (Seinfeld & Pandis 2006 Ch. 23 §23.3, p. 1038-1042, IPCC TAR 2001 baseline reproduced in S&P Figure 23.6 / Table 23.4). The component aggregates the five canonical anthropogenic radiative-forcing channels — CO₂, CH₄, N₂O, tropospheric O₃, and the halocarbon family — and exposes per-channel and total radiative forcing as observable outputs. Each channel is parameterized as a dimensionless scaling factor f_X applied to a fixed IPCC TAR reference forcing ΔF_X_ref: ΔF_X = f_X · ΔF_X_ref. The total ΔF_total = Σ ΔF_X is the headline anthropogenic radiative-forcing diagnostic. Observed-only algebraic component: six equations on six state variables (ΔF_CO2, ΔF_CH4, ΔF_N2O, ΔF_O3, ΔF_halo, ΔF_total) driven by five scaling-factor parameters (f_CO2, f_CH4, f_N2O, f_O3, f_halo) and five reference-forcing constants (ΔF_CO2_ref = 1.46, ΔF_CH4_ref = 0.48, ΔF_N2O_ref = 0.15, ΔF_O3_trop_ref = 0.4, ΔF_halo_ref = 0.34, all in W/m^2). No time derivatives, no PDE, no coupling. Migrated from GasChem.jl@8c12c048 src/climate_forcing.jl:104 (`GHGForcing` @component). The scaling-factor design lets a downstream consumer adjust each individual channel without forking the component — useful for (i) reproducing the IPCC AR4/AR5/AR6 revisions to the industrial-era forcing values (e.g., AR5 CO₂ ≈ 1.82 W/m² vs TAR 1.46), (ii) sensitivity studies that probe each channel's contribution to the total, and (iii) attribution scenarios that zero out individual channels (f_X = 0 ⇒ ΔF_X = 0). At the defaults (all f_X = 1), ΔF_total = 1.46 + 0.48 + 0.15 + 0.4 + 0.34 = 2.83 W/m² which matches the upstream IPCC TAR 2001 industrial-era forcing total (S&P p. 1039, sum of the five well-mixed-GHG + O3 channels excluding aerosols).