I’m excited to share this guest post from Elizabeth Dunn and Jiaying Zhao, authors of the book, Leave the Lights On: How Joyful Decisions Can Save Our Species.
Leave the Lights On is a bold invitation to reimagine climate action not as a burden, but as an opportunity to build a brighter future—without guilt, without gloom, and without giving up the things that make life worth living. With warmth, clarity, and a refreshingly optimistic voice, Zhao and Dunn reframe what it means to “do your part.” Because sustainability doesn’t lie in doing everything, it lies in doing something, joyfully.
Elizabeth Dunn is Professor of Psychology at the University of British Columbia, where she conducts original research on happiness. Her work has been featured in The New York Times, The Wall Street Journal, The Washington Post, Los Angeles Times, The Atlantic, TIME, Rolling Stone, and Harvard Business Review; and on numerous podcasts and television shows, including Hidden Brain, NPR’s Short Wave, The Happiness Lab, Ten Percent Happier with Dan Harris, Morning Joe, and CBS Mornings. Dunn spoke on the TED mainstage in 2019, and her talk was selected as one of the top ten TED talks of the year. She is an avid skier and surfer, and she survived a shark attack.
Jiaying Zhao (JZ) is Professor of Psychology and Sustainability at the University of British Columbia, where she founded and directs the Behavioral Sustainability Lab. JZ designs innovative and impactful behavioral solutions to boost climate action. She has worked with NASA, NOAA, and the US and Canadian Forest Service to develop pathways to net zero. JZ has appeared on numerous podcasts and in documentary films, including Why Is This Happening? with Chris Hayes and Close the Divide. Her research has been featured in The New York Times, The Washington Post, The Atlantic, TIME, The Economist, Scientific American, CNN, and NBC. In 2023, JZ gave a TED talk on climate strategies rooted in happiness, which was selected as one of the top “TED Talks to be a better you” in 2024. JZ is a zealous foodie who eats one epic meal per day.
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One of the most common decisions we make, each and every day, is what to put in our mouths. Daily decisions like what we eat can have important implications for both climate change and our own happiness. Our new book LEAVE THE LIGHTS ON reveals how tweaking these everyday decisions can nudge us toward a tipping point of mass action (without tipping us into burnout.)
As professors, we’ve encountered lots of students who are depressed about climate change. So, we’ve designed a Happy Climate workshop for students who want to learn how to make better decisions, in order to live happier, lower-carbon lives. We start by sharing some key facts about the carbon emissions in a variety of foods. Then, in small groups, the students work together to select changes they want to make in their own lives to cut carbon and get happier. (If you’d like to run a workshop like this for your own students, community group, family, or friends, you can access all our workshop materials for free at happyclimate.org.)
During one of these workshops, a student told us that he was planning to give up cheese, now that he recognized its surprisingly high carbon impact. While telling us this, his face crumpled with sadness, as he envisioned his cheese-less future. Being a happiness researcher, Liz could not condone this plan.
Fortunately, cutting back on carbon doesn’t have to mean permanently abandoning cheese, corned beef, and other carbon-intensive foods. Just having these high-carbon foods a little less often can make a substantial difference. For example, eating beef once a week, rather than every day, would cut your carbon emissions by more than three tons this year.
And there’s more good news: Having high-carbon foods less often might actually enhance your capacity to enjoy them. Liz explored this idea in a study involving chocolate. Although chocolate is a plant-based product, it carries a surprisingly high carbon impact because most chocolate-growing operations entail massive deforestation.
To investigate whether reducing chocolate consumption could enhance the pleasure of eating it, Liz teamed up with psychologist Jordi Quoidbach. True to his Belgian heritage, Jordi loves chocolate—and he’s a master of maximizing pleasure. So, he conducted a little experiment, inviting students to come to Liz’s lab and taste some chocolate. He measured how much they savored the chocolate—not only by asking them but also by instructing a research assistant to surreptitiously observe how much enjoyment they displayed. Then he gave some of the students, chosen at random, a big bag of chocolate bars. He told them to eat as many as they comfortably could over the next seven days. Meanwhile, he politely asked another group of students to refrain from eating any chocolate for one week. The remaining students were assigned to the control group and didn’t receive any special chocolate-related instructions. He brought everyone back to the lab one week later. At their second visit, the students ate some more chocolate and completed measures of savoring, just like in the previous visit.
The first thing that popped out of the data was that the students savored the experience of eating chocolate in the lab less the second week than they had the first week. This simple finding captures what is perhaps the most depressing discovery to emerge from happiness research: The more we repeat a positive experience, the less we tend to appreciate it. Psychologists refer to this process as hedonic adaptation. And it has been observed in all kinds of places, with all kinds of people, across a vast range of positive experiences, from receiving money to getting married.
When it comes to food, though, there is a way to short-circuit hedonic adaptation. Jordi discovered that people who had been asked to forgo chocolate for one week exhibited a preserved capacity to savor it. And at the end of the week, they got a bigger happiness boost from eating chocolate compared with the students who had received the bag of candy or had simply continued with their regular consumption habits.
So, eating high-carbon foods less often may increase our capacity to enjoy them. That said, you could eat meat every day for the rest of your life, while still cutting carbon and enhancing pleasure. The key here is to consider portion size. At Ruth’s Chris Steak House in Dallas, the first option on the steak menu is a 16-ounce New York strip—a meal that will cost you 100 pounds of carbon (which is equivalent to driving 112 miles). But you could cut your carbon impact in half by choosing the 8-ounce steak from the same cut, which goes by the name “petite filet,” subtly implying it’s for children or maybe French people.
At first glance, choosing the smaller steak might seem like a sacrifice. But research suggests that people underestimate the pleasure of smaller portions. For example, in one study, French children were offered tasty snacks, such as brownies, that ranged from the manufacturer’s rather modest suggested serving size up to a supersize snack that was more than twice as large. Petite filets aside, it turned out that even French children expected to enjoy the larger snacks more. But unless they were very hungry, their actual enjoyment was unrelated to the size of their snack.
How could this be? After all, it seems like more bites of a delicious food should add up to greater pleasure. The culprit here is a basic principle of physiology known as sensory-specific satiety. According to this principle, the pleasure of eating a specific food peaks with the first bites, and then begins to decline. Early studies documented this principle in monkeys, whose neurons fired less enthusiastically when they were fed more of the same food—but responded with renewed strength when they were given a different food. If you’ve ever declared that you’re full and then moved on to eat dessert with gusto, you’ve experienced sensory-specific satiety. As well as explaining the “dessert stomach,” sensory-specific satiety underpins food writer Michael Pollan’s argument that “the banquet is in the first bite.”
Even small changes in our eating habits can make a real impact on both climate change and our own happiness. But there are many other opportunities to tweak our decisions in positive ways. In our book Leave the Lights On, we show how people can make smarter, happier decisions about everything from how to spend money and where to go on vacation to whether to have children and what kind of job to take. If you make a positive change in your life to cut carbon and get happier, we would love to hear about it in the comments!