Next Saturday, the autumn equinox will mark the beginning of fall in the Northern Hemisphere. For some, though, the real start of fall is when the leaves change color. But scientists say climate change is affecting both the timing and intensity of fall foliage. John Yang speaks with Bill Keeton, a professor of forest ecology at the University of Vermont, to learn more. PBS NewsHour is supported by - https://www.pbs.org/newshour/about/funders