Reuters/Stanford Ipsos poll: Only 27% of Americans believe that if global warming is happening, it is caused mostly by things people have been doing

Poll shows growing belief that global warming is occurring - The Hill's E2-Wire

“A large majority (71%) believe that if warming has been happening, it has been caused either partly (45%) or mostly (27%) by things people have been doing. 27% believe warming to be the result of natural causes,” a summary states.