On a recent 14.5-hour flight from Los Angeles to Sydney, I had time to read the columnist Charles Krauthammer's collection of essays, "Things that Matter." It made for a disturbing flight.

I have enjoyed Krauthammer's writing over the years, but there was something in his book that I found deeply troubling: his description of himself as an "agnostic" on climate change. He "believes instinctively that it can't be very good to pump lots of carbon dioxide into the atmosphere," and yet he "is equally convinced that those who presume to know exactly where that leads are talking through their hats."

The word that I found most galling was "agnostic" — not only because Krauthammer is a trained scientist, but also because the word was used repeatedly by former Australian Prime Minister John Howard when he addressed a group of climate change deniers in London in late 2103. "Part of the problem with this debate," Howard told the assembled skeptics, "is that to some of the zealots involved their cause has become a substitute religion."