The Faint Young Sun Paradox: A Simplified Thermodynamic Approach

Table 1

Possible scenarios of ancient surface temperatures under maximum power output regime. Input data: 𝜌, 𝛾, 𝑅 (one case). 𝑆/𝑆₀ is calculated according to Gough equation for a given age. The fifth column corresponds to our calculated temperatures. For the first row data 𝑅=0.95 was considered. The sixth column shows the surface temperatures estimated from 𝑆(𝑡) values reported in Table 11 of [25].

Albedo 𝜌	Greenhouse coefficient 𝛾	Solar constant 𝑆/𝑆0 (normalized)	Time BP (Gyr)	Surface temperature, 𝑇1 (K)	Surface temperature, 𝑇1 (K)
0.17	0.06	0.7-0.8	4.5–3.6	273.7–283.04	280.1–283.01
0.25	0.15	0.72	4.47	273.7	280.33
0.30	0.20	0.74	4.04	273.1	279.74
0.35	0.30	0.72	4.47	273.8	280.01
0.40	0.35	0.73	4.25	273.1	280.03