The most audacious claim - among many - in Saturday night's Democratic presidential debate was made by Sen. Bernie Sanders. Climate change is the cause of terrorism, he said.
He doubled down on the claim on Sunday: "The reason is pretty obvious: If we are going to see an increase in drought and flood and extreme weather disturbances as a result of climate change, what that means is that people all over the world are going to be fighting over limited natural resources," he said on a Sunday morning talk show.
That's ridiculous on its face. But let's look at his claim more closely, just in case we're missing something.
First, as his second quote shows, Sanders is essentially saying that terrorism is an outgrowth of resource wars.
Resource wars are real, of course, and they happen from time to time. Clearly, a driving force of the Japanese attack on the United States in 1941 was about resources necessary for Japan's military - rubber, oil and iron ore. And Germany did invade Russia largely for its wheat and its land.
Still, those attacks wouldn't have happened if not for those nations' military aspirations. World War II was a war about ideologies. Japan wanted to dominate the Greater East Asia Co-Prosperity Sphere; Germany wanted to conquer Europe.
But what's happening in Syria isn't a resource war. Paris wasn't attacked because it's too hot, or too dry, or crops failed, or species died off.
For one thing, Syria has always had cycles of drought. That's nothing new; much of the region is desert.
As the Intergovernmental Panel on Climate Change itself admits, "there is not enough evidence at present to suggest more than low confidence in a global-scale observed trend in drought or dryness since the middle of the 20th century due to lack of direct observations, geographical inconsistencies in the trends, and dependencies of inferred trends on the index choice."
If the eternally panic-stricken IPCC won't make that connection, then Sanders shouldn't either.
But there's no drought in Syria at present; there's something far worse. There's an ideological war taking place. And ISIS isn't fighting to capture water resources or land for farming. They're fighting to install a theocratic dictatorship. ISIS's opponents are not being killed because they're competitors for scarce resources. They're being killed for not believing the right things.
Second, the math in Sanders' statement just doesn't work. It requires a series of events that simply haven't happened.
As Jeff Kueter of the George C. Marshall Institute notes, "Man's activities have to warm the Earth, that warming has to produce demonstrable environmental side effects, those side effects have to overwhelm human tolerance and adaptive or responsive efforts, and then, and only then, are the conditions for conflict sowed."
Sanders' claim that climate change causes terrorism is one of those things that looks plausible, until the facts are examined more closely - like peak oil, or a population bomb, or Al Gore's claim that the arctic ice caps would be gone by 2013.
But the pesky facts keep getting in the way.