AT THE 2010 Shanghai World Expo, audience members strapped themselves into moving seats to watch a 360-degree screen. The scene on display was a quixotic vision of the city in 2030.

Not long ago, while crashing with my parents for a few days, I had the opportunity to sift through a wicker box stuffed with memorabilia from my youth: cards, letters, notes scribbled furtively in class.

An optimistic environmentalist may sound like an oxymoron (or perhaps just a moron).

After my daughter was born, whenever I heard about parents who refused vaccines, I’d feel a flare of hostility. Not because I couldn’t relate to them—as an easily spooked new mom, I could relate all too well. No mother is thrilled to see a needle jabbed into her child.

If a single book has haunted the environmental movement, it’s The Population Bomb, by Stanford biologist Paul Ehrlich.