Three days before CNN hosted the fifth Republican presidential debate, leaders from every country in the world struck a historic climate change agreement in Paris to reduce fossil fuel emissions and face up to one of the greatest threats facing our country and our planet. The Paris agreement was a front page story in newspapers throughout the U.S. and around the globe. So considering that the Pentagon says climate change “could impact national security” and experts have identified a relationship between global warming and the rise of ISIS, the issue clearly belonged in the December 15 CNN debate, which co-moderator Wolf Blitzer described as a “discussion about the security of this nation.”

CNN's own Michael Smerconish pointed to the significance of the Paris climate agreement in the cable outlet's debate preview coverage the night beforehand, yet CNN failed to ask a single question about the agreement or climate change more broadly during the debate itself. While GOP candidates may have their own political reasons for avoiding the issue -- and a couple of them dismissively brought climate change up on their own -- CNN is a news organization with a responsibility to press the candidates for our nation's highest office on the most important issues facing the country and the world, particularly when there are major new developments to address.

CNN did not immediately respond to a request for comment on why the network did not deem the Paris climate agreement worthy of a question (or three) during the debate. So for now, we're only left to wonder how such an inexcusable omission could occur.