ScienceDaily (Oct. 14, 2010) — Sixty-three percent of Americans believe that global warming is happening, but many do not understand why, according to a national study conducted by researchers at Yale University. The report titled "Americans' Knowledge of Climate Change" found that only 57 percent know what the greenhouse effect is, only 45 percent of Americans understand that carbon dioxide traps heat from the Earth's surface, and just 50 percent understand that global warming is caused mostly by human activities. Large majorities incorrectly think that the hole in the ozone layer and aerosol spray cans cause global warming. Meanwhile, 75 percent of Americans have never heard of the related problems of ocean acidification or coral bleaching.
http://www.sciencedaily.com/releases/2010/10/101014121119.htm