Presently, the annual average of CO2 is about 400 ppm, and the concentration is increasing by about ____ ppm per year.
a. 2
b. 5
c. 8
d. 12
e. 15
Question 2
Everything else being equal, the more CO2 in the atmosphere, the ____.
a. cooler the surface air
b. warmer the surface air
c. more cloud cover of Earth
d. greater the amount of precipitation
e. the more likely ice will form in polar regions