In Iowa, even without admitting that climate change is real, farmers are acting as if it is, spending millions of dollars to alter their practices. They are adding tile drainage to their fields to cope with increased floods, buying bigger machinery to move more quickly because their planting window has become shorter, planting a month earlier than they did 50 years ago, and sowing twice as many corn plants per acre to exploit the additional moisture, says Gene Takle, professor of meteorology at Iowa State University in Ames. "Iowa's floods are in your face—and in your basement—evidence that the climate has changed, and the farmers are adapting," he says.
Local officials have seen the connection, too. After the huge floods of 2008, the Iowa town of Cedar Falls passed an ordinance requiring that anyone who lives in the 500-year flood plain must have flood insurance—up from the previous 200-year flood requirement. State Sen. Robert Hogg wants to make the policy statewide. He also is pushing to restore wetlands that can help soak up floodwaters before they devastate cities. "Wetland restoration costs money, but it's cheaper than rebuilding Cedar Rapids," he says. "I like to say that dealing with climate change is not going to require the greatest sacrifices, but it is going to require the greatest foresight Americans have ever had."
Right now, that foresight is more myopia, many scientists worry. So when and how will people finally understand that far more is needed? It may require more flooded basements, more searing heat waves, more water shortages or crop failures, more devastating hurricanes or other examples of the increases in extreme weather that climate change will bring. "I don't want to root for bad things to happen, but that's what it will take," says one government scientist who asked not to be identified. Or as Nashville resident Rich Hays says about his own experience with the May 2010 deluge: "The flood was definitely a wake-up call. The question is: How many wake-up calls do we need?"
Reporting for this story was funded by the Pew Center on Global Climate Change.