Last week, we presented “Seven graphs that should make the Obama campaign very nervous.” In short: Drought means higher food staple prices, which means higher food-and-many-other-things prices, just in time for Election Day. The post was what folks in the trade call “kinda-scientific.”

Well, someone went ahead and went straight “scientific” on the issue. Namely, Larry Bartels of Princeton University. In a post at The Monkey Cage, he explains that there actually is a direct correlation between drought and reduced support for the incumbent president.

Several years ago, Christopher Achen and I examined the impact of droughts and floods in presidential elections throughout the 20th century. We found a surprisingly strong and clear tendency for voters to punish the president’s party when their states were too wet or too dry. In the 2000 election (the most recent in our data), we estimated that Al Gore got about 2.8 million fewer votes than he would have under ideal climatic conditions.

Do voters really expect President Obama to make it rain? Probably not. But that won’t prevent them from punishing him if it doesn’t. When conditions are hellish, policy discussions are likely to be less edifying than expressions of frustration.

You might think that civilization has matured beyond the point at which people look to the sun for leadership. Nope. The sun might turn out to be Obama’s toughest opponent. Vote Ra, 2012!

Not pictured: the vice presidential candidate. (Image courtesy of ynotpic.)