Question 2
In terms of long-term temperature increases in the atmosphere, which of the following is TRUE?
A) Average global temperature has risen 5C in the 20th century.
B) No changes have been observed in the 21st century.
C) The greenhouse effect has never been shown to be real.
D) Increases in greenhouse gases have been observed.
E) It appears that we can readily curb the carbon dioxide problem.
