text: The third advantage is beneficial implicattions for carbon emissions and the environment. In the fourth passage, Michael Sivak says," What most intrigues me is that rates of car ownership per household started to come down two to three years before downturn. I think that means more fundamental is going on." The article says, " if the pattern persists-and many sociologists believe it will-it will have beneficial implications for carbon emissions and the environment, since transportation is the second largest source of America's emission."