Dubner and Levitt have written some counterintuitive points about global warming. You may have heard that buying locally grown produce is better for the environment because the closer your food, the smaller the carbon footprint. But according to Dubner, buying locally sourced food doesn't necessarily cut down on greenhouse gases.
"If you do the numbers, you find that food that's imported from halfway across the world has a much smaller carbon footprint than locally grown food, because ... big farms are more efficient," he said. "Something like 85 percent of the energy that goes into producing food is in the production phase, not the transportation phase."
In fact, Dubner says we spend too much time worrying over what comes out of the back of our cars, and not enough on what comes out the back of some farm animals.
"If you really are worried about greenhouse gases, you should be worried about something like methane, which is about 25 times more powerful than carbon dioxide as a greenhouse gas. And if you're really worried about methane, then you should really worry about, let's say, cows."
Cows and other ruminants, he says, release methane every time they exhale or pass gas. "So, if you drive a Prius to the grocery store and then you buy some hamburger meat, you're canceling it out 25 times over. You wanna eat more kangaroos," Dubner said.
Why kangaroos? Because they don't emit methane. (It's worth noting that while methane is more damaging as a greenhouse gas than carbon dioxide, there is less of it in the atmosphere. Methane's overall climate impact is nearly half that of carbon dioxide.)
CLICK HERE to read an excerpt from "SuperFreakonomics."