Answer to Question 1Without any greenhouse gases, the Earth's average temperature would be between -22C and -36C.
These temperatures are too cold for liquid water to exist on the surface, and life would not be as
abundant as it is today
Answer to Question 2The major greenhouse gases are water vapor (60-70), carbon dioxide (15-20), halocarbons (7-
10), methane (5-7), and nitrous oxide (1-3). Water vapor contributes the most (60-70) to
the greenhouse effect