If a hypothetical future Earth has increased the amount of radiation emitted to 604 W/m, calculate the hypothetical global surface temperature in degrees Kelvin and then in Celsius

For amount of radiation from a hot body there is Stefan's Boltzman's law which is given below.

E = e σ T⁴

E is amount emitted, e is emissivity, σ is stefan's constant = 5.67 X 10⁻⁸ W / m². for earth e =.85 approx

E =.85 x 5.67 X 10⁻⁸ x T⁴

604 =.85 x 5.67 X 10⁻⁸ x T⁴

604 = 4.82 x 10⁻⁸ T⁴

T⁴ = 125.31 x 10⁸

T = 3.3457 x 10²

= 334.57K

Temperature in Celsius = 334.57 - 273

= 61.57 Celsius.