Consumers’ estimates of emissions are systematically inaccurate across lifecycle stages
Across eight studies, the research demonstrates that consumers systematically misestimate food-product emissions by underestimating high-impact lifecycle stages and relying heavily on numerical anchors, leading to suboptimal purchasing decisions that prioritize packaging reductions over more impactful agricultural improvements.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Imagine you are trying to guess how much "carbon pollution" a single apple creates from the moment it grows on a tree until you eat it. Scientists call this the product's "lifecycle." It's a bit like a relay race where the pollution baton is passed through different stages: growing the food (agriculture), turning it into a product (processing), wrapping it (packaging), moving it to the store (transportation), and finally, you eating it. We know that some runners in this race are much faster (or in this case, much dirtier) than others. For most food, the "agriculture" runner is a giant, carrying the vast majority of the pollution, while the "packaging" runner is tiny, carrying just a tiny bit.
Now, imagine you are a brand trying to sell a greener apple. You might say, "We cut our packaging pollution by 20%!" That sounds great, right? But here is the tricky part: if you don't know that packaging is only a tiny slice of the total pollution pie, you might think that 20% cut is a huge win. If you knew that agriculture is actually the massive 70% slice, you might realize that cutting agriculture pollution by 20% would save way more pollution than cutting packaging by the same amount. The big question is: Do regular shoppers actually know which stage of the apple's life is the dirtiest, or do they just guess?
This paper, written by Tim Döring and Katherine Burson, dives into that guessing game. They wanted to see if people can accurately estimate how much pollution comes from each stage of a food product's life. They ran eight different studies with over 3,600 people, asking them to guess the pollution shares for things like milk, bread, and cookies. The researchers found something surprising and a little bit silly: people are terrible at this. Instead of seeing the huge gap between the dirty agriculture stage and the clean packaging stage, everyone's guesses were suspiciously similar. It's as if everyone looked at the pollution relay race and thought, "Well, every runner probably carried about the same amount of dirt."
The researchers discovered that people's brains are being tricked by the way the question is asked. When you ask someone to split 100% of the pollution among six stages, their brains tend to just hand out an equal share to everyone (about 16% each), like a kid dividing a pizza into six equal slices without looking at the toppings. This is called an "anchor" effect. Even when the researchers gave people a specific number to start with—like "imagine 100 light bulbs worth of pollution"—people still stuck close to that number, regardless of whether the stage was actually huge or tiny.
The most fun part of the discovery is what happens when you change the game. In one experiment, the researchers asked people to estimate the pollution for "production" as one big chunk. In another group, they asked the same people to estimate "production" but split it into three tiny sub-steps. The result? The group that saw the three steps added up their guesses to be almost three times higher than the group that saw it as one step! It's like if you asked someone how much a whole pizza costs, they say $10. But if you ask them how much the crust costs, the sauce costs, and the cheese costs separately, they might say $4 for the crust, $4 for the sauce, and $4 for the cheese, totaling $12. The total pizza didn't change, but the way the question was broken apart made the price look different.
This isn't just a math error; it changes how people shop. In a final test, people had to choose between two grocery stores. One store promised to cut pollution in agriculture by 20%, and the other promised to cut pollution in packaging by 20%. Even though cutting agriculture pollution would save way more carbon in the real world, the people who thought packaging was a bigger source of pollution (because they guessed it was) chose the packaging store. The authors ran a simulation suggesting that if everyone made this same mistake, it could mean millions of tons of extra carbon pollution every year.
So, the paper suggests that while we are getting better at talking about green products, our brains are still stuck in "equal share" mode. We aren't seeing the giant pollution giants (like farming) and the tiny pollution sprites (like packaging) for what they really are. Instead, we are just guessing, and our guesses are often pulled toward whatever number or rule the question gives us. This means that when companies say "20% less packaging," we might cheer too loudly, not realizing that a "20% less farming" claim would actually be the real hero of the story. The authors aren't saying we can't fix this, but they are pointing out that we need to show people the real sizes of these pollution stages, not just the percentages, or we'll keep making the wrong choices.
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