The climate silence is complete: Climate change got not a single mention in any of the three presidential debates nor in the vice presidential debate this year. That hasn’t happened for 24 years.

In the final debate on Monday night, focused on foreign policy, moderator Bob Schieffer didn’t ask anything about energy or climate, but he posed a couple of open-ended questions that would have given easy entrée to either candidate had they any inclination to bring up the topic: “What is America’s role in the world?” and “What do you believe is the greatest future threat to the national security of this country?”

In a debate about global challenges and global threats, Romney and Obama both chose to say nothing at all about the climate crisis, the most global of all challenges and threats.