Amelia Fortgang remembers her grandmother taking her to a peace march when she was just 3 years old. The pair held aloft a sign her grandmother made reading, “War causes global warming.” Amelia’s other grandmother was an elementary school art teacher. Decades ago, she planted a redwood tree with her students. “The students asked her what the point of planting it was when it wouldn’t grow quickly enough for them to enjoy,” Amelia said. “She told them that they were planting it for future generations.” Fifty years later, Amelia is that future generation. When she went to the same elementary...