27) Over long periods of time, Earth’s atmosphere ________.
A) naturally increases and decreases in temperature
B) stays at a precise, consistent temperature
C) has continued to show an increase in average temperature
D) has continued to show a decrease in average temperature
28) The UN Intergovernmental Panel on Climate Change reported that current global warming is
caused by ________.
A) natural historic trends
B) sun spots
C) rising ocean temperatures
D) human activity
29) What do scientists consider the most alarming issue related to increasing global air
temperatures over the past century?
A) the fact that temperatures did not fall
B) the small amount of temperature increase
C) the relative speed of temperature increase
D) the impacts of warming on developed nations
30) Few people today dispute that ________.
A) Earth’s temperature is rising
B) Earth’s ecosystems are disappearing
C) Earth’s temperature is stable
D) human activity is causing global warming
31) In the greenhouse effect, ________ are affected by gases in Earth’s atmosphere.
A) water temperatures
B) air and water temperatures
C) air, land, and water temperatures
D) water and land temperatures