Radiative-Forcing

Climate-feedback diagnostic (Seinfeld & Pandis 2006 Ch. 23 §23.4 Eqs. 23.1-23.4 and Eq. 23.7 p. 1045) — the linear-response relation between a top-of-atmosphere radiative forcing perturbation ΔF and the equilibrium surface temperature change ΔT_s through the feedback-amplified climate sensitivity λ. Six observed-only algebraic equations on six state variables (ΔT_s the feedback-amplified equilibrium response, ΔT_0 the no-feedback Planck response, λ_0 the no-feedback sensitivity factor, ΔF_e the efficacy-weighted effective forcing, ΔF_r the forcing equivalent of realized warming, ΔT_unrealized the warming commitment) driven by five input parameters (ΔF the forcing perturbation, λ the feedback-amplified sensitivity, λ_CO2 the CO₂-doubling sensitivity reference, E_i the efficacy of the forcing agent, ΔT_r the realized warming to date) and two reference constants (ΔF_2xCO2 the CO₂-doubling radiative forcing, ΔT0_2xCO2 the no-feedback temperature change for CO₂ doubling). No time derivatives, no PDE, no coupling. Migrated from GasChem.jl@8c12c048 src/climate_forcing.jl:32 (`ClimateFeedback` @component). The component extends the no-feedback Planck response of the sibling `ClimateSensitivity` model (components/gaschem/radiation/climate_sensitivity.esm, S&P §4.2 Eqs. 4.8-4.10) by introducing the feedback-amplified sensitivity factor λ and the warming-commitment relation ΔT_unrealized = (ΔF - ΔF_r)·λ that captures the lag between achieved (ΔT_r) and equilibrium (ΔT_s) warming under a non-zero forcing perturbation. At Earth's nominal 2×CO₂ forcing ΔF = 3.7 W/m² and λ = 0.8 K·m²/W (IPCC AR4 central estimate), the component reproduces the textbook canonical ΔT_s ≈ 2.96 K equilibrium warming (S&P Page 1040), λ_0 ≈ 0.338 K·m²/W no-feedback Planck response, and ΔT_unrealized ≈ 0.49 K warming commitment for the present-day p. 1045 scenario (λ = 0.7, ΔF = 1.7, ΔT_r = 0.7).

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).

Global Warming Potential (GWP) for atmospheric trace species with first-order exponential-decay perturbation lifetimes (Seinfeld & Pandis 2006 Ch. 23, Eqs. 23.5-23.6 and Problem 23.3, p. 1050). The GWP is defined as the ratio of the time-integrated radiative forcing from a pulse emission of 1 kg of species A to that of 1 kg of CO₂ over a specified time horizon t_f. For species whose atmospheric perturbation decays exponentially as exp(-t/τ_A), the time-integrated forcing reduces to the closed-form expression τ_A · (1 - exp(-t_f/τ_A)), so the GWP becomes GWP = a_A · τ_A · (1 - exp(-t_f/τ_A)) / [a_CO2 · τ_CO2 · (1 - exp(-t_f/τ_CO2))]. The component is observed-only: five algebraic equations on five state variables (decay_integral_A, decay_integral_CO2, AGWP_A, AGWP_CO2, GWP) driven by three input parameters (τ_A the species lifetime, a_A the radiative efficiency relative to CO₂, t_f the time horizon) and two CO₂-reference constants (τ_CO2 the effective CO₂ lifetime, a_CO2 the reference radiative efficiency). No time derivatives, no PDE, no coupling. Migrated from GasChem.jl@280ee50f src/climate_forcing.jl:182 (`GlobalWarmingPotential` @component). The GWP framework is the IPCC standard for comparing the climate impact of different greenhouse gases on a common (CO₂-equivalent) scale and underlies the conversion between mass emissions of CH₄, N₂O, halocarbons, and other well-mixed GHGs to their CO₂-equivalent emissions for policy and inventory accounting. Canonical GWP₁₀₀ values (IPCC AR4 Table 23.1, S&P p. 1042): CH₄ ≈ 23, N₂O ≈ 296, SF₆ ≈ 22800 — the framework's three-order-of-magnitude span anchors the design choice of representing GWP as a derived ratio rather than a hardcoded table.