Shared plot

Radiative forcing ΔF = a·ln(C/C₀) in W/m² as a function of CO₂ concentration C (ppm), referenced to pre-industrial C₀ = 280 ppm. Drag the coefficient a (IPCC uses ≈5.35); the markers are fixed at the ≈5.35 values, so the curve meets them at the default. The logarithmic relationship means each successive doubling adds the same forcing (~3.7 W/m²).