As record heat hits cities across the U.S. and Europe, experts are warning about the growing risks of heat waves. “Start Here” host Brad Mielke breaks down his conversation with Jeff Goodell, the author of “The Heat Will Kill You First: Life and Death on a Scorched Planet” on why it’s so dangerous. SUBSCRIBE to ABC News on YouTube: bit.ly/2vZb6yP Latest updates: abcnews.go.com Watch FULL EPISODES on Hulu: abcn.ws/3bzvQQn #news #starthere #climatechange #abcnews