“Your Bowl of Rice Is Hurting the Climate Too” reads a Bloomberg headline from June. “Rice cultivation could be as bad for global warming as 1,200 coal plants, so why aren’t consumers more bothered? Eco-conscious consumers are giving up meat and driving electric cars to do their part for the environment, but what about that bowl of rice?” I was irritated as soon as I read it. It was probably a combination of the whataboutism and the focus on a food that is eaten much more in Asia and Africa than the U.S. and Europe when overall Americans and Europeans have caused a lot more greenhouse gas emissions per capita than Africans and Asians. To top it off, what should I make of the 1200 coal plants number? How much of a climate impact “should” the staple food of billions of humans have?
The article is full of figures. They all sound impressive, but I didn’t really understand how to interpret them. Rice is “just as damaging over the long term as annual carbon dioxide emissions from fossil fuels in Germany, Italy, Spain and the U.K. combined.” (Do Germany, Italy, Spain, and the U.K. all rely on fossil fuels for most of their energy? How do the populations of those four countries compare to the population that relies on rice for a significant proportion of their calories? How should I compare climate impact of the farming of one crop for the entire world to the climate impact from all causes in a few countries?) “Global production of milled rice has increased 230% since 1960.” (How much has the population increased since then?) Rice production emits “twice as much of the harmful gases as wheat.” (Is more rice or wheat consumed?) “Growing rice in flooded conditions causes up to 12% of global emissions of methane, a gas blamed for about one quarter of global warming caused by humans.” (What are the major sources of anthropogenic methane emissions? Methane from rice farming causes 3% of anthropogenic global warming. Is that a lot? Food is one of the least optional sources of greenhouse gas emissions, after all. Plenty of people live without cars, flights, or electricity, but calories are a must.)
I’m not writing this post solely because I wanted to complain about one article that bugged me, as fun as that is. It’s important to think about how we interpret headlines like this one. Many people have had traumatizing experiences with mathematics and don’t feel comfortable reasoning about numbers or statistics, but as a society we are also on the whole deferential to numbers. An article can get away with throwing statistics around without properly contextualizing them because people won’t question them, or don’t know the right questions to ask, or think an argument that refers to a lot of numbers must be a sound one.
Furthermore, humans’ perceptions about what to focus on when it comes to pollution and climate change can be skewed. Recently, some environmental activists have zeroed in on plastic straw waste, causing a reaction from disability activists, who say plastic straws are important accessibility items for some people. The fracas concerns less than a tenth of a percent of the plastic pollution in the ocean. A plastic straw ban is basically symbolic. (A 2018 study estimated that about half of the plastic pollution in the famous Great Pacific Garbage Patch consists of lost or discarded fishing nets.) With a limited mental bandwidth for caring about and taking action on various environmental issues, where should rice fall on that list?
But most of all, I finished reading the article honestly unsure how to understand the impact of rice farming on the environment. I wanted to find the numbers that would help me put the situation in context.
Back to rice.
Reading the article, my first question was what proportion of the world’s calories come from rice. That seems like an important basic fact that would help me understand the other numbers. Ricepedia, a rice information site run by CGIAR, an agriculture research organization, says 19% of “global human per capita energy” comes from rice. About 3.5 billion people get at least 20% of their calories from rice, and about half a billion get most of their calories from rice. Other sources I found had similar numbers, reporting 16–20% for the proportion of the world’s calories that come from rice.
A fifth of the total calories humanity consumes is a lot. Corn (maize) and wheat have similar numbers. Together, the three plants provide more than half of our calories. Of course growing something that sustains so many people will have an impact on the environment. I was somewhat surprised that rice, corn, and wheat were so similar in the proportion of calories they provide. It helped put the fact that rice farming causes twice as much greenhouse gas emission as wheat in perspective.
My next question was how rice’s impact stacks up against impacts from other foods and how that compares to its importance as a source of nutrition. The statistic that rice produces 12% of anthropogenic methane and that the methane produced by rice farming makes put about half of crop-related greenhouse gas emissions come from a white paper prepared by the Environmental Defense Fund (EDF). (The white paper isn’t actually about the methane emissions; it is about a study that shows that attempts to mitigate methane emissions may be increasing the emissions of nitrous oxide, another potent greenhouse gas.)
The EDF bases their estimates on the 5th Assessment Report of the United Nations Intergovernmental Panel on Climate Change (relevant chapter here). According to those numbers (specifically figure 6.8, if you’re following along at home), the main food-related contributors to anthropogenic methane emissions are rice paddies and cow farts. (They don’t quite use that terminology.) Together, those sources account for about 40% of anthropogenic methane emissions, with rice producing about 30% of that amount. If all foods emitted the same amount of methane, rice would only produce 20%, so it produces about 1.5 times as much as it “should” proportionally. But the real story is that the methane emissions of food are very disproportionate, with rice and ruminants almost completely responsible! When all greenhouse gas emissions from food are taken into account, rice emits more greenhouse gases per calorie than wheat or corn but less than fruits, vegetables, legumes, or any animal sources. See this working paper from the World Resources Institute for more granular data. If the EDF is correct that rice emits more nitrous oxide than previously understood, those numbers may underestimate rice’s impact, but it is still dwarfed by the impact of animal-based foods.
I haven’t answered all the questions the article left me with, but I actually feel a lot more equipped to understand the impact of rice on the environment. Some of the numbers from the article still perplex me. I don’t know what to make of the comparison to 1200 coal plants or the assertion about Germany, Italy, Spain, and the U.K. Comparing the climate impact of fossil fuel use in all sectors in four countries to the impact of a food that is eaten all over the world just doesn’t make sense to me. The statistic about rice production increasing since 1960 is a little more meaningful. The world population today is about 2.5 times as much as it was in 1960 (so it has increased 150%). Rice production, though, is about 3.3 times as much, so rice production has grown more than the population by a moderate amount.
Personally, these statistics will probably not change my rice consumption. I don’t eat a lot of rice anyway. It’s a part of my diet, but I get a lot more of my calories from wheat, and I think decreasing my consumption of dairy products would probably be more effective in reducing the greenhouse gas emissions of my diet than reducing the amount of rice I eat would be. More broadly, rice is an important source of nutrition and part of the cultural heritage for billions of people and can be grown in places other crops can’t, so I bristle at any implication that people who rely on rice as a staple should cut down on it or are making irresponsible choices by surviving, and throwing shade at consumers who reduce their meat consumption but not rice seems particularly unhelpful.
That said, the statistics I found about the environmental impact of rice farming did surprise me. I didn’t realize it was such an outlier from other grains in terms of its climate impact, and I am glad that research continues into how to grow rice in less damaging ways. My dive down the rice rabbit hole also highlighted to me how difficult it can be to obtain and interpret information about how our choices affect the environment. Figuring out the full context for the numbers is difficult, and I hope more climate change research organizations will continue to make it easier for everyone to get the information they need to make informed choices.