Earth Day, when people around the world come together to support the protection of the environment, is commemorating its 50th anniversary this year. The covid-19 pandemic will mean celebrations are muted, but it is worth looking back at its achievements and seeing if it can still make a difference in today’s world.

I was there at the beginning. In 1970, I was a 17-year-old intern, part of a roughly 80-person team running Earth Day from its headquarters in Washington DC. The event was described as a national day of environmental teach-ins. Earth Day founder Gaylord Nelson turned much …