Research Project Asks: What’s the Climate Impact of Your Grocery List?

One of the least discussed, but potentially most devastating, effects of climate change is what it is doing to food systems. As Lew Ziska, associate professor of environmental health sciences, has demonstrated through his research and summarized in his 2022 book Greenhouse Planet, hotter temperatures supercharge the proliferation of weeds and sap the nutritional value of crops.

At the same time, our food choices are helping to drive climate change; the livestock sector alone constitutes nearly 15 percent of human greenhouse gas emissions. Lowering agricultural emissions by decreasing livestock consumption will both improve population health outcomes and reduce climate change. To this end, Ziska, Donald Edmondson, Associate Professor of Behavioral Medicine at Columbia University Irving Medical Center, and Sining Zhou, ‘20 MPH, senior project designer at GoodRx and associate research scientist at Columbia Mailman, are developing a method to inform consumers about the climate impact of their food choices.

The three researchers started by conducting a meta-analysis of existing food lifecycle assessment methodologies to create a reference metric. Going forward, they will apply this metric in the development of a mobile app to guide consumer food choices by presenting “carbon foodprints” that reflect food choices and guide grocery shopping and eating choices. Their effort is one of eight Columbia Mailman Centennial Grand Challenges projects that bring together an interdisciplinary team to address the key public health needs of today and the coming decades.

In the following Q&A, Ziska discusses the ongoing project and its implications.

What are the origins of your project?

Ziska: It came about at a meeting a long time ago, when I was talking about what to do to help inform consumers about the amount of carbon that’s associated with the food that they purchase. I had just purchased a new car, which came with a bill of sale that told me the carbon footprint of the car I purchased. I thought, wouldn’t it be nice to have that for the food that you purchase? And to get a sense of that, so that people who are concerned about their carbon contribution can look at it.

People are more and more concerned about what’s happening in the environment. There are many choices we can all make to reduce the impact of climate change. A big one is the food we eat. We’re building this app to give them an accurate picture of their “carbon foodprints” (we say “foodprints,” not footprints). If I change my source of meat from beef to chicken, I save 1,000 pounds of CO2. In addition to that, I lower my cholesterol. What’s not to like about that?

How do you think this will impact consumer choices? Corporate choices?

Ziska: We hope that the average consumer will take away that they’re not helpless when it comes to climate change. That if they have this information, they can make personal choices that will have a major impact in terms of their carbon contribution. They can make a difference at the individual level by becoming informed and knowing a little bit more about their food choices.

This is less science than it is hope: corporate behavior is modeled on what consumers purchase. If consumers purchase options are less carbon intensive, then that will shift what they produce. Fingers crossed; it will make a big difference!

Where are you in the project now?

Ziska: We’ve been focusing on putting the software together so we can read UPC codes of any food in the market. We’re also looking at how the app can support behavioral changes for consumers.

What has collaborating with Donald Edmonson and Sining Zhou been like?

Ziska: Collaborating is really wonderful. In chemistry, we learned about things that make the reaction go faster. What’s happened here is that this kind of collaboration is a catalyst to make things go faster. There’s a catalyst of having different viewpoints and different disciplines. These are the things that really define the Dean’s Grand Challenges. Not just words on the paper, but actual outcomes that will make a difference.