Greenhouse Effect Calculator

Calculator Inputs

Solar constant, S

W/m² (Earth ~1361).

Planetary albedo, α

Unitless, 0–1 (Earth ~0.30).

Atmospheric emissivity, ε

0 = transparent, 1 = blackbody.

CO2 concentration, C

ppm (example: 420).

Reference CO2, C0

ppm (example: 280).

Sensitivity, λ

K per (W/m²) (example: 0.80).

Enable CO2 forcing calculation

Add CO2 warming to surface temperature output

Reset Formula used How to use Example data

Solar input and effective temperature

ASR = S (1 − α) / 4

Te = (ASR / σ)^1/4

ASR is absorbed shortwave radiation at the top of atmosphere. σ is the Stefan–Boltzmann constant.

One-layer grey atmosphere greenhouse

Ts = [ (ASR/σ) / (1 − ε/2) ]^1/4

Ta = Ts / 2^1/4

ε is the atmospheric longwave emissivity. This idealized model assumes a single isothermal layer emitting equally upward and downward.

CO2 forcing and linear response

ΔF = 5.35 ln(C / C0)

ΔT = λ ΔF

C and C0 are CO2 concentrations in ppm. λ is a user-chosen temperature response parameter in K per (W/m²).

Example uses Earth-like defaults (S=1361, α=0.30, ε=0.78, C=420 ppm, C0=280 ppm, λ=0.80).

Case	Te (K)	Ts (K)	Ts − Te (K)	ΔF (W/m²)	ΔT (K)	Combined Ts (K)
Default parameters	254.578	288.064	33.486	2.169	1.735	289.799

Interpretation: This model is highly simplified; it is best for sensitivity exploration, not detailed prediction.