Assume the simple 1-layer greenhouse model of the atmosphere outlined in class. Today, the average
albedo of the earth is ~ 30%; the fraction of terrestrial radiation absorbed by the greenhouse layer is
~77% and the average surface temperature of the earth is ~ 288 K. Consider the following past
scenario, ~ 3.8 billion years ago. At that time, the energy output of the sun (i.e., the solar constant) was
weaker than today by 30%, but higher CO2 levels likely provided a stronger greenhouse. Assume the
greenhouse layer captured 95% of terrestrial radiation, and assume the albedo is the same as today.
Incorporating these changes, predict quantitatively if liquid water would have been present on earth
(calculate the average surface temperature to predict this).