NASA climate scientist James Hansen and 30 other demonstrators were arrested in West Virginia while protesting the practice of mountaintop-removal coal mining, which Hansen says President Obama must ban as the U.S. weans itself off fossil fuels. Hansen; actress Darryl Hannah; Michael Brune, executive director of the Rainforest Action Network; and Ken Hechler, a 94-year-old former congressman, were among those arrested as they blocked traffic on a highway in front of a Massey Energy coal plant in Sundial, West Virginia. “We have to phase out greenhouse gas emissions over the next 20 years,” said Hansen. “Where should you start? Well mountaintop removal is producing only seven percent of the nation’s coal and it’s a destructive practice.” The mining technique, which involves blasting the tops off Appalachian mountains to get at coal seams below, has buried more than 800 miles of streams in mining debris and has severely damaged or destroyed an area of forest nearly as large as Delaware. Protesters have recently carried out acts of civil disobedience against companies involved in mountaintop removal, including chaining themselves to mining equipment.