What happened to the environmental movement?

Adam Rome’s genial new book, “The Genius of Earth Day: How a 1970 Teach-in Unexpectedly Made the First Green Generation” (Hill & Wang), brings to life another era. We’re as distant from Earth Day as the Battle of Gettysburg was from James Monroe’s reëlection, and Rome evokes a United States that feels, politically, like a foreign country. There were a number of liberal Republicans. Most active members of environmental groups were hunters and fishermen. The Sierra Club was an actual club that required new members to be proposed by old ones. The Environmental Defense Fund was two years old. Things like bottle recycling and organic food were exotic.