Democratic incumbent Sen. Mark Udall’s (Colo.) wife called for a carbon tax while appearing in a new anti-oil video produced by Leonardo DiCaprio. “People are ready for conversation,” says Maggie Fox, Udall’s wife and former president of Al Gore’s Climate Reality Project, in the Green World Rising video, entitled, “Carbon.” “They’re ready to understand that carbon pollution is causing this challenge and that there is a simple solution: put a price on carbon pollution,” she says. DiCaprio is releasing a series of environmentalist videos on climate change, the first focusing on gathering support for a cap and trade system. A...