"We've had decades and decades, and maybe even centuries, of periods of time when there's been a tremendous rise in temperature and then a tremendous fall in temperature. And all you've got to do is look at the Little Ice Age of the mid-last millennia as an example. And so we've got to single out what's natural and what's man made before you can make policy."
--Sen. Charles Grassley (R-Iowa)
Two-thirds of Iowa, the nation's largest corn producer, is suffering extreme or exceptional drought, part of a crisis across the Midwest farm belt that, according to the U.S. Department of Agriculture, has reduced corn yield per acre to its lowest level since 1995. Is global warming to blame? That will be clearer if such droughts become more frequent. But it's a very bad idea to bet the farm against the possibility.Jim Watson / AFP / Getty Images