With the U.S. Senate’s rejection of legislation last week that would have limited the EPA’s power to regulate carbon dioxide emissions, climate change is once again grabbing national attention. If you listen to the organic-only food movement’s true believers, you’d think 19th-century food production is a panacea for rising greenhouse gas emissions. But emerging research is challenging organic farming’s “climate friendly” image.

A new analysis in the Proceedings of the National Academy of Sciences finds that the intensification of farming brought about by the Green Revolution massively slowed global warming. The use of high-yield hybrid crops, pesticides, and fertilizers enabled farmers to produce more food without having to tear down forests for more cropland. Overall, this forest-saving bottom line helped keep 600 billion tons of carbon dioxide out of the atmosphere—equivalent to one-third of all emissions between 1850 and 2005. (Read that again. The numbers are right.)

And at The New York Times, Texas State University professor James McWilliams blogs about the findings of California plant pathologist Steve Savage. Described by McWilliams as someone with a “deep admiration” for organic farming, Savage nevertheless discovered that organic methods can have serious costs:

[Savage] came to the stark conclusion that, regarding GHG emissions and organic agriculture, “gain in soil carbon on an organic farm comes at the substantial carbon cost of methane and nitrous oxide emissions.”

Savage works from two defining premises. The first is that the methods typically used by organic growers to fertilize row crops—namely planting cover crops and applying manure or compost—can, under certain circumstances, create “substantial” levels of nitrous oxide and methane emissions. How substantial? That brings us to Savage’s other critical premise: 83 percent of the U.S.’ agricultural production today is in row crops (corn, wheat, hay, and soy) grown on a large scale. It is on the basis of these premises that Savage calculates what would happen to GHG emissions if all these staples were produced organically. His answer, which he claims to have checked out with hundreds of scientists, is eye-opening to the extreme: organic methods lead to a “carbon footprint” that’s fourteen times higher than if conventional methods were employed.

In other words, organic production’s reduction of atmospheric carbon dioxide comes at a cost of more methane and nitrous oxide, which are more potent greenhouse gases than CO2. We don’t take positions on climate change, but together these two analyses put a dent in the assumption that organic is a superior system for the environment.

And the environmental costs don’t stop with emissions. The late, great Norman Borlaug, the father of the Green Revolution, once noted that organic farming could only sustain about 4 billion people globally. Why? In part because to create organic nitrogen (as opposed to the widely used synthetically produced nitrogen), we’d need another 5 or 6 billion head of cattle to produce manure. University of Manitoba agronomist Vaclav Smil puts the figure in the U.S. alone at an additional 1 billion livestock (for manure) and 2 billion acres of forage crops (for the livestock). That’s the size of the entire lower 48 states—and he’s not counting the other 4 or 5 billion head of livestock required for the rest of the world to go organic.

What would the anti-livestock-farming Humane Society of the United States say? (Why doesn’t someone ask them?)

Assuming we’re not likely to get 2 billion volunteers to starve to death, steering the world toward organic food production is just not practical. And thanks to this latest research, there’s more literature showing that it’s not very “green” either.