Here’s some CO2-free food for thought.

One single loaf of bread contributes as much to global warming as one pound of carbon dioxide, according to a new study published Wednesday in Nature Plants.

Food production and consumption is the cause of approximately one-third of total greenhouse gas emissions. This factoid led a research team at University of Sheffield to delve into the supply chain process of bread.

“We found in every loaf there is embodied global warming,” Liam Goucher, lead author of the study, said in a statement. He added that consumers are likely aware of the environmental impacts of a product’s plastic wrapping, but not of the product itself.

The scientists analyzed a single loaf of bread’s CO2 contributions, including growing and harvesting the wheat, milling the grain, producing the flour to baking the bread and finally, packaging the loaf.

Once the ingredients for a 1.8 lb. loaf of bread are grown and harvested and the finished product is baked and wrapped, the atmosphere will have received 0.4 pounds of CO2 from baking, .06 lbs from milling and a whopping 0.56 lbs from the fertilizer used to harvest the wheat.

Wheat is fertilized with ammonium nitrate, which releases N20, nitrous oxide, into the atmosphere. N20 is a greenhouse gas that some experts say is 300 worse than C02 in terms of trapping heat. Global agriculture uses more than 110 million tons of fertilizers a year.

Cutting back on fertilizer might help, but that means slashing wheat production, which means less food. And the study notes that currently, there aren’t any incentives in place to encourage cutbacks.

“Whose responsibility is it to bring about the implementation of these interventions: the fertilizer manufacturer, the farmer, the retailer or the consumer?” Richard Bruce, a co-author of the paper, said in the statement. “These findings raise a very important issue.”

The world added 38.2 billion tons of carbon dioxide to the atmosphere in 2011, according to a study published in Nature Climate Change. That number was a three percent increase from 2010.