The G-20 meeting in Pittsburgh is considering ways to reduce subsidies that articifically keep down the price of fossil fuels, thus contributing to greenhouse gas emissions. But what the G-20 nations will probably not talk about are the even more expensive set of subsidies that contribute to climate change in less obvious ways: farm subsidies.
I can think of two immediate examples: First, ethanol subsidies, which cost the U.S. $3 billion in 2007, lead to increased corn production. Deroy Murdock has written about the effects on emissions:
According to a study in the August 1 Atmospheric Chemistry and Physics, scientists discovered that “the use of several agricultural crops for biofuel production and climate protection can readily lead to an enhanced greenhouse warming by N2O emissions.” Nobel Prize-winning chemist Paul Crutzen and his three American, Austrian, and Scottish co-authors explain that nitrogen-rich fertilizers used in ethanol-driven corn production yield nitrous oxide, a greenhouse gas. Hence, “the relatively large emission of N2O exacerbates the already huge challenge of getting global warming under control.”
But doesn't more ethanol help the climate because it's a cleaner fuel than gasoline? That's true, but, as Richard Posner has argued, simply slapping a higher tax on CO2 emissions would achieve the same goal at lower cost and without the increase in N2O emissions.
Second, the U.S. spends $4 billion a year on dairy subsidies. That means more cows out on the farm, which means a whole lot more methane in our air. Apparently, just one cow produces almost four tons of methane gas a year, which contributes to the greenhouse effect. See the MSNBC video below for more. (HT: the Tax Foundation.)