Bill Nye brought science into kids’ lives and made us laugh. He inspires memes, has his own bow tie line and has appeared on numerous television shows, including, earlier this month, alongside Arnold Schwarzenegger, National Geographic Channel’s Explorer series. He’s even been a guest on Dancing With the Stars. But under the stardust is a serious scientist who started life as a humble mechanical engineer at Boeing and is now on a mission to combat scientific ignorance and fight against climate change. His new book, Unstoppable: Harnessing Science To Change The World, mixes science and his trademark humor to rally a new “Greatest Generation”—ours—to solve a global climate change crisis that he believes is more threatening to our survival than World War Two.