DJ at Asymptotic Life crunched the numbers and found that beef has a high carbon footprint, but (surprising to me) rice more than an order of magnitude higher.
Two foods stood out from the pack as far worse than the others: Per pound eaten, rice creates 276 pounds of CO2 , and beef 11.5 pounds of CO2 per pound. Compare that with cheese (1.64 pounds), chicken (0.5 pounds), or soy (0.04 pounds).
Rice?
(From the comments) Because the soil is kept underwater, rice cultivation emits methane, which is 20 times more potent as a greenhouse gas than CO2. I’ve ranked it by its CO2 equivalence.
He says we can reduce our carbon footprint by eating less beef, which is certainly true. But the question remains, what of the literally billions of people for whom rice is an everyday food essential.
I wonder, can rice be grown less destructively?
Um, how many miles per gallon do you think a Stealth Bomber gets? How much CO2 do you think comes off the Beijing Expressway every morning?
Rice is not the problem here.
Actually, I do believe that there is a way to grow rice sans flooded fields and as I recall, the yeilds were comparable if not better. Can’t remember the reference but I spose some time on the Google could muster it up…
BTW, I came up with that number (276 pounds of CO2-equivalence per pound of rice) by dividing the EPA estimate of U.S. rice-related emissions by the USDA figures on tons of U.S. rice production. I do not assume that the same would be true in a family rice plot worked by hand and fertilized with manure (where most of the world’s rice is grown), and I have no data to work with for comparison.
As for relevance, the average American eats 20 pounds of rice per year, producing (indirectly) over 2-1/2 tons of CO2-equivalence. That’s 1/10 of our per capita greenhouse emissions. That’s not the biggest source, but it’s definitely a significant one.
America should stop growing rice in this manner. In most of the rice growing contries, 80% of it is grown using rainfall,field operation is done using manual labour with no Co2 emission other than people breathing out. very little chemical fertilizers are used. The production is about 3 tons of grain and 10tons of straw & roots which are mostly cabohydrates, product of photosynthesis and all the carbon in carbohydrate is fixed from atmosphere, thus reducing Co2 in the atmosphere.
The people growing rice using high inputs should delearn and relearn how to grow rice more efficiently.
Non flooded/intermittantly flooded rice (system of Rice Intensification) can reduce the Methane emissions and increase the yield significantly, and feed the americans also.
The problem is, the straw and roots, which if composted would decompose into the same CO2 it absorbed from the atmosphere when it grew, when covered with water decomposes into methane instead. Same for the buffalo manure that’s often used as fertilizer. Methane is 21 times more potent as a greenhouse gas than CO2.
To misquote an old TV commercial, “It’s the water.”
How to grow rice without paddies (and with 30% more yield!) HERE:
http://www.sciencedaily.com/releases/2007/10/071014202450.htm
A lot more information re: growing rice without paddies:
http://ciifad.cornell.edu/sri/countries/india/indiaarchives.html
Picture comparing rice plant grown w/ SRI methodology to one grown with traditional paddies.
http://www.news.cornell.edu/stories/Oct06/CIIFAD.Alcan.Prize.html
Dear Sue,
Thank you for calling attention to the System of Rice Intensification as a means for reducing the GHG impact of rice production. The estimate of irrigated rice’s generation of CO2 equivalence surely derives from the large amounts of methane produced by continuously flooded rice paddies, since methane is a much more potent GHG than CO2. We are assessing whether there could be some offsetting increase in nitrous oxide when rice paddies are not kept flooded, since NO2 is as much more potent than CH4 as CH4 is compared to CO2. The effects in any case will vary across agroecosystems, depending on soil structure, physical characteristics like drainage, amounts (if any) of inorganic N added to the field which aerobic microorganisms will convert into NO2. These are complex questions. But we have reason to believe that changing the management of rice paddies from continuous flooding to only alternate wetting and drying, with mostly aerobic soil conditions, will reduce the ‘carbon footprint’ of rice production — with higher yields, often much higher yields, and the environmental benefit of reduced water requirements and reduced agrochemical applications. Higher yields will themselves reduce the GHG effect per kg of rice. I hope that anyone interested in this subject will make the effort to learn more about SRI.
In my post “Consider Your Diet,” I incorrectly stated that rice prodices 276 pounds of CO2 per pound of rice grown. I am unable to substantiate that figure.
In fact, estimates of CO2 equivalency for methane emitted from rice production range from 0.6 (much lower than beef) to 35 pounds (much higher than beef) per pound. This does not include the N2O emissions. And it’s a ridiculously large range, though scientific research by IRRI does indicate that rice-related methane emissions can vary by more than 100-fold depending on soil, temperature, and cultivation methods.
I am still trying to get at the truth of the matter, and have contacted several experts. When I have a better answer, I will provide an update.