The economists and activists who hope to stop global warming know that small measures won’t cut it. Which is why “conscious consumption” — taking individual actions to reduce your carbon footprint — often looks like a distraction: Purchasing hybrid cars, embracing plant-based diets and installing solar panels may even be counterproductive, to the extent that these actions divert attention from the major policy changes needed to parry the climate threat.
In his influential book “The Uninhabitable Earth,” for example, the journalist David Wallace-Wells describes conscious consumption as a cop-out, “arising from that basic promise extended by neoliberalism: that consumer choices can be a substitute for political action.” Joshua Goldstein, a professor emeritus of international relations at American University, has likewise argued that while he drives an electric car and has solar panels on his roof, he’s under no illusion that these moves have broader consequences: “For consumers in the industrialized world to signal virtue with their individual actions is irrelevant,” he has said.
The problem, such critics argue, is that global warming has deep systemic causes that are little affected by individual steps alone. Unless we undertake massive public investment in renewable-energy infrastructure and adopt stiff taxes on carbon — moves that require major governmental action — we’ll have virtually no hope of averting the cataclysmic suffering that continued warming portends.
I used to share their skepticism. But my study of “behavioral contagion” — social scientists’ term for how ideas and behaviors can spread through populations like infectious diseases — has changed my view. The environmental impact of seemingly insignificant voluntary actions is far greater than most people realize, for two related reasons. First, they have the power to shift how the people around us behave. Second, and more important, they change who we are, making us much more likely to support the large-scale policies needed for progress. Conscious consumption alone certainly can’t stop the warming threat, but it’s an essential step on our path forward.
Economists are generally skeptical of self-sacrificing behavior because of what’s known as the free-rider problem. Since costly individual acts of self-restraint have only negligible environmental impact, economists predict that rational, self-interested individuals won’t take them. For instance, if someone buys a Toyota Prius hybrid — which costs several thousand dollars more than a comparable vehicle with an internal-combustion engine — and no one else does, there’s no discernible effect on overall emissions. She has spent the extra money for no reason. Alternatively, if everyone else buys a Prius but she doesn’t, she reaps the environmental benefits for free. Many solutions to environmental problems follow this logic and would therefore seem to require that we make decisions collectively, not individually.
Economists have other reasons for rejecting conscious consumption. Although the Prius emits about 50 percent less CO2 than similar non-hybrid cars, even greater reductions in CO2 could be achieved by buying a cheaper vehicle and using the savings to purchase carbon offsets — sponsoring carbon-absorbing reforestation, for instance. It may feel better to drive the Prius, but cold economic logic seems to favor offsets.
But these traditional arguments start to break down once you bring social contagion into the picture. That’s because the direct effect of owning a Prius is only a small part of its total impact.
Human nature is more complex than assumed in the simple models once favored by most economists. Our judgment about whether a house is adequate, for example, depends not only on its absolute features but also on how it compares with surrounding houses. We also value our reputations. It’s when we consider the effects of our behavior on our peers, and vice versa, that the consequences of individual decisions to reduce carbon use start to grow in importance. We know, for example, that decisions about car purchases are influenced by the actions of neighbors. In a 2008 study, economists from UCLA and Helsinki examined Finnish records of more than 210,000 vehicle purchases (new and used) from 1999 through 2001. They found that people were 12 percent more likely to purchase a car on a given day if one of their 10 nearest neighbors had purchased one during the preceding 10 days.
And the purchase of low-emissions vehicles carries special cachet, at least in some populations. In a 2015 study, three American economists estimated that almost $600 of the value of the distinctively shaped Prius could be attributed to “environmental status signaling” — the amount people were willing to spend to demonstrate their eco-consciousness. (The researchers calculated that figure in part by comparing the Prius’s price to that of the Honda Civic hybrid, which has similar environmental advantages but looks exactly like the standard Civic, except for a subtle badge. The Civic sends a very weak “signal” to onlookers.)
Together, these studies suggest that peer influence and reputational concerns have helped to drive the growing popularity of hybrids: Carmakers sold more than 400,000 of them in the United States last year, compared with 9,000 in 2000. (Low oil prices have caused a dip since the 2013 peak of nearly 500,000, which demonstrates that social contagion is not the only factor shaping sales — and that a carbon tax is still important.)
Buying carbon offsets might still have greater impact in the short run, but you can’t see them, so their purchase is less likely to be contagious. (Only about a tenth of Americans have purchased an offset even once.) The widespread embrace of hybrids over the past two decades has almost surely resulted in larger CO2 reductions than a campaign promoting standard cars plus carbon offsets would have. What’s more, hybrids are a pivotal step on the path to plug-in electric cars, an important destination in the climate battle.
Food consumption is also strongly subject to behavioral contagion, as is obvious from the popularity of fads like the Atkins, ketogenic, Mediterranean, paleo, South Beach and other diets. Because food production accounts for one-quarter of greenhouse gas emissions worldwide, encouraging the adoption of vegetarian or meat-light diets is especially important. Fortunately, research shows strong evidence of contagion in this area, too — producing both good effects and bad. A study of more than 1,500 military families conducted between 2013 and 2017 found that members of those families sent to new locations where the obesity rate was one percentage point higher than in their prior posts were 5 percent more likely to become obese during their new assignments. Cutting down on meat not only reduces emissions directly but also influences the food choices of others.
Solar-panel installation is perhaps the most extensively documented example of behavioral contagion in the environmental domain. Google’s Project Sunroof website allows you to calculate how much money you could save by installing solar panels; it also lets you see aerial photos of your neighborhood, with red dots marking houses with solar panels. Even casual perusal makes clear that houses with red dots tend to be clustered together.
One study, by professors at New York University and Yale, examined solar-power contagion in California, looking at more than 85,000 panel installations across the state between January 2001 and December 2011. Using data supplied by utility companies, matched against demographic information about purchasers, they found significant effects of peer influence at both the Zip code and (especially) street levels. In the average-size Zip code, of 4,960 people, the scholars found that each new installation raised the daily probability of another installation by 0.78 percentage points. That may sound like a small effect, but the upshot is that each new installation stimulated a second one within four months, on average — and the rate accelerated. Bigger installations also inspired larger peer effects. Contagion rates would gradually diminish, of course, as the number of candidate houses for new installations shrunk. But since social networks don’t include only those living close by, the influence of these installations would also extend well beyond neighborhood boundaries.
Such ripple effects alone help to counter critics’ skepticism about conscious consumption. But the second, more important, reason individual decisions matter is that they also deepen citizens’ sense of identity as climate advocates.
Contrary to the presumptions of orthodox economic theory, our preferences aren’t a fixed part of our identities. They’re under constant construction and revision. As the historian Will Durant summarized Aristotle’s view of the process: “We are what we repeatedly do. Excellence, then, is not an act but a habit.” Aristotle’s aim was to explain why someone might refrain from cheating even when no one is looking — which is similar to asking why someone might engage in conscious consumption: Why sacrifice when the individual act has no direct benefit to you? When rules are strictly enforced, many behave honestly simply because they fear being punished. But following the rules eventually becomes a part of our identity that governs our choices, even when there’s no one around to punish our dishonesty.
Over time, taking small steps to lower your carbon footprint forges the general habit of behaving in a climate-friendly way. And the development of that perspective is a crucial step toward greater political engagement on the issue. Conscious consumption is neither “irrelevant” nor merely a way to advertise our virtue. It creates cascading changes in social behavior, as well as deeper changes in how we view the world. Conscious consumption serves ultimately as a way to build citizens who favor strong climate legislation, who write checks to politicians willing to take up the cause and who knock on doors to help those politicians get elected.
Keeping global warming at bay will indeed require a massive social movement — one that defeats climate obstructionists resoundingly at the polls — just as critics of conscious consumption have long insisted. But those critics fail to see how small, individual choices can set in motion the mighty revolution they envision.