Dan Galpern is bicycling 4,705 miles, through 19 states and two Canadian provinces, to accomplish one goal — pressure the White House to use its full executive authority in order to address climate change. During more than 11 years as a legal and policy advisor to James E. Hansen, former director of NASA’s Goddard Institute of Space Studies, Galpern witnessed little coherence in federal climate change approaches, as the government failed to assume leadership on mitigation efforts. “No legal liability to date has been attached to prior carbon pollution, and there should be,” he says, adding fossil fuel producers have not only profited by ...