Environmental Leader: Most Americans Get a Failing Grade in Climate Change Facts While 63 percent of Americans believe that global warming is happening, many do not understand why, according to a Yale project study on climate change communication. The study finds that eight percent of Americans have knowledge equivalent to an A or B grade, while 40 percent would receive a C or D, and 52 percent would get an F. The study, “Americans` Knowledge of Climate Change” (PDF), also finds gaps in knowledge …