Hillary Clinton highlights her plans to combat global warming. Donald J. Trump dismisses the science as a hoax.
A Gallup poll in March found that 65 percent of Americans believed that climate change was caused by human activity, an increase of 10 points from a year earlier. The poll found that 38 percent of Republicans believed the same thing, an increase of four points from a year earlier. The poll also found that 76 percent of Americans ages 18 to 29 accepted that human activity is behind climate change.