Extreme weather is sweeping across the United States, from scorching heat in the Southwest to uncontrollable wildfires in California, to deadly flooding in Appalachia. In West Virginia, at least 23 people have died in once-in-a-thousand-year flooding, and a number of people remain missing across the state. Meanwhile, wildfires are raging up and down the state of California. At least two people have died, and hundreds of homes have been destroyed. May was the 13th straight month to smash global temperature records, amid increasing human-fueled global warming. We speak with Michael Mann, a professor of atmospheric science at Penn State University. Mann was in Phoenix last weekend to testify before the Democratic National Platform Draft Committee meeting.