A symbolic turning point for U.S. climate policy, and by extension the world, happened when President Ronald Reagan removed the solar panels that his predecessor, Jimmy Carter, had installed at the White House, signaling a return to business as usual — i.e., burning more fossil fuels and hastening a growing climate crisis.

After the death of Pope Francis, the Roman Catholic Church’s choice of successor could be a similar sliding-doors moment. When much of the world, including its biggest economy, is retreating from climate activism and embracing a cynical climate "realism,” the Vatican has a chance to stand out by electing another vocal environmentalist to lead nearly 1.4 billion Catholics.

And as with Carter and Reagan, solar panels are involved again.