Which substance is of great concern to scientists studying human-generated greenhouse gases, and is thought to increase such that the earth's climate will be irrevocably changed by 2020?
A)chlorofluorocarbons
B)carbon dioxide
C)methane
D)nitrous oxide
E)ozone

Question

Quizplus · Accepted Answer

Carbon dioxide is the most prevalent greenhouse gas emitted by human activities, such as burning fossil fuels. The concentration of carbon dioxide in the atmosphere has already increased significantly and is expected to continue to rise, causing further warming of the earth's climate. While the timeline of irrevocable change is uncertain, scientists agree that urgent action is needed to address the issue of carbon emissions.

Which Substance Is of Great Concern to Scientists Studying Human-Generated