evidence: Why Doesn’t Everyone Believe Humans Are Causing Climate Change? [...] Yet back home, President Obama still faces an electorate that doesn’t believe climate change is caused by humans. Only 40% of Americans attribute global warming to human activity, according to a recent Pew Research Center poll . This, despite decades of scientific evidence and the fact that Americans generally trust climate scientists . [...] Kahan’s ideas are based on his own surveys of the American public. In one recent study of 1,769 participants recruited through the public opinion firm YouGov, he assessed people’s "ordinary climate science intelligence" with a series of climate change knowledge questions. He also collected demographic data, including political orientation. Kahan found no correlation between one’s understanding of climate science and his or her acceptance of human-caused climate change. Some people who knew quite a bit on the topic still didn’t accept the premise of anthropogenic climate change, and vice versa. He also found that, as expected, conservatives are less likely to accept that humans are changing the climate.