Viable solutions to the climate crisis depend on human behavior as much as they do on technological innovation and robust economic policy. After all, citizens around the world must adopt those new technologies, be willing to accept that robust policy, and embrace rapid changes in lifestyles and consumption habits.

But rapid change is difficult. In the industrialized world we are now accustomed to profligate consumption of materials and energy, and our institutions and economies are fashioned around this reality. Even though this course of history wasn’t inevitable, the forces of chance, economics, innovation, and social progress have played their part. Their legacy: billions of consumers with high expectations for affordability, convenience, security, and enjoyment, and a choice environment in which those expectations are best met by unsustainable choices.

This is not to exclusively blame the current climate emergency on consumers’ demand for consumption, or on producers’ enthusiasm to supply it. Even with the best of intentions from both sides, it will take time to break into a new pathway and enable consumers to make truly sustainable choices. To understand the root of this behavioral “lock in,” we must look at the interplay between three factors: our individual psychology, our social environment, and the material world. Each presents not only unique barriers to rapid change but also distinct opportunities.

Diagnosis: Psychological, Social, and Material Factors Driving Behavioral “Lock In”

Many quirks of our psychology cause our actions, choices, values, and opinions to be self-reinforcing, digging us into a particular pathway resistant to change. To name a few, this includes status quo bias and loss aversion (causing us to prefer the known or the incumbent over the unknown or the new); confirmation bias and motivated reasoning (causing us to strengthen existing opinions through a self-serving and biased interpretation of new information); the sunk-cost fallacy (causing us to continue pursuing our chosen pathway beyond all reason because of the effort and cost already expended); and habit (automated routines in response to familiar situations, which tend to strengthen over time).

And so while we are capable of changing our minds and our behavior, our brains don’t make it easy. It is not trivial, for example, to convince someone that their planet-harming behaviors are immoral: we have a powerful desire to see ourselves in a positive light, and the weapons of denial, self-persuasion, and rationalization are at our disposal to resist such attacks on our conscience. Even if we want to change, old habits die hard. For instance, it can be difficult for experienced drivers to change their driving style to be more fuel efficient—and far easier for learners for whom driving is not yet in the “autopilot” portion of their cognition.

But we must look beyond the workings of the brain for a full understanding of behavior. Individual brains are also embedded within a social and physical context. The essence of this interplay is that we don’t make choices wholly independently and rationally, but respond to social and physical cues in our environment through largely automatic cognitive shortcuts. These heuristics have evolved to help us navigate a complex world with minimal mental effort, but they also mean our choices and actions are profoundly shaped by our surroundings.

For instance, we tend to do what most other people do (conformity), in part because their actions are a useful source of information (social proof—e.g., if everyone else is starting to buy electric cars, we might surmise they’re worth looking into). Social norms thus tend to reinforce themselves, because the more people who do something, the stronger the influence on others to follow suit. A positive feedback loop, this creates a pathway of increasing momentum, whether that’s good or bad: just as electric car purchases can grow exponentially as they become normalized, so can panic buying during a national emergency.

Many of these heuristics that shape our decisions also reflect cues in our physical environment. For example, unless there are strong reasons not to, we normally follow the path of least resistance (taking options that are close, convenient, or available); choose middling options from within a range; stick with defaults (failing to make an active choice, accepting the default selection); and opt for choices that are prevalent or more salient.

In sum, every time we make a choice we are not faced with a blank canvass. We are far more likely to choose the option that we chose before, that is easy or available, that is familiar, that has become normal, that our culture views as high-status or desirable, and so on. These factors can’t be reinvented overnight, nor are they typically under the control of individuals. The ease, availability, desirability, familiarity, and normality of, say, different transport choices is dictated by decades of infrastructure, urban planning, institution design, economic policy, technological development, social norms, personal habits, and culture. This means individual efforts to swim against this current often require great effort and personal sacrifice, and thus are often thwarted by further psychological barriers including conflicting motivations (the cheap option is rarely the sustainable option); limited willpower and short-term decision-making (immediate gratification or convenience rarely aligns with aspirations to be sustainable); and collective action problems (we’re reluctant to make individual compromises if others aren’t also doing their bit, leading to a tragedy of the commons).

In other words, our past choices, individual and collective, establish the psychological, social, and material context against which new choices are made, and thus have a gravitational pull that takes a force of will to escape.

All of these factors explain why many of us are capable of caring deeply about the planet, having good intentions, and feeling like the world is out of step with our green values—yet we mostly still conform to the unsustainable norms of our society.

The conclusion, for a policymaker or influencer, is that to change behavior at the scale needed to mitigate environmental decline, we must leverage all three of these factors—psychological, social, and material. Psychologically, we can prompt, support, and incentivize the right choices, and address (or harness) cognitive biases to allow good intentions to flourish into actions. But that’s rarely enough, and it is often more effective to tweak the social and material reality around us to make those good choices easier, more normal, and the default options. Such changes can be big (new infrastructure or economic policy) or small (tweaking the framing of options or removing small hassles). Done effectively, at scale and with foresight, these actions might begin to carve a new path of least resistance toward sustainable outcomes across society. These in turn may become self-reinforcing and entrenched in all the ways described above, locking us into more sustainable choices.

Let’s take a closer look at some of the specific behavioral barriers, and consider potential solutions.

Defaults

The challenge: Knowingly or not, we make hundreds, if not thousands, of decisions every day, and for the most part we fail to make an active decision and so stick with the default outcome. There are good reasons for this: we lack the cognitive bandwidth to engage with every moment of choice or possible divergence; default options are often perceived as an implicit recommendation or norm; and if we’ve been doing something for a while with no adverse effects, it’s a safe bet to continue. The problem is, for many of us, the default way to get to work is to drive; the default settings on thermostats and washing machines are rarely the most efficient; the default energy tariff is usually the most expensive one, not the greenest; and the default food choice at catered events is rarely the most sustainable. If such defaults remain unquestioned or unchanged, they reinforce incumbent practices of unsustainable behavior, and present a barrier to behavior change.

The solution: We can equally use defaults to our advantage and to lock in sustainable choices. For example, a study in Germany found defaulting customers into a green electricity tariff increased the number of customers on that tariff tenfold (Ebeling and Lotz 2015). Since few of us regularly switch our energy tariff, such changes have lasting effects, particularly if the volume of consumers switching leads to changes in policy and supply-side infrastructure that further entrench a new, sustainable status quo.

To give another example, in the United Kingdom defaulting employees into private pension schemes has led to 9 million new savers (DWP 2017)—so why not take the next step, and default those savings into an environmental, social, and governance investment? After all, there is a default investment option, which the vast majority of pension savers never change. Such a move would push trillions into the green economy, also catalyzing more sustainable outcomes across society.

Inertia: Habit, Status Quo Bias, Loss Aversion, and Procrastination

The challenge: There are many reasons to stick with what we know.

Behavioral economists have shown that losses hurt more than gains please us (loss aversion) (Tversky and Kahneman 1991). This systematically biases us toward the status quo, since when faced with a change, we overemphasize what we’ll lose relative to what we’ll gain. This is further exacerbated by our tendency to be risk-averse and uncertainty-averse, meaning that the status quo, even if imperfect, is often preferable to an alternative which brings some unknowns. For instance, why risk switching to a green energy supplier if the current supplier has been okay? Or why switch to an electric car with unknown range if there’s no real need to?

Such biases also influence public consent to policy. For example, studies on clean air zones, plastic-bag levies, and smoking bans often reveal public disapproval before implementation but greater support after, when the benefits have been felt and the downsides found to be less onerous than anticipated.¹

We also have a tendency to procrastinate. This is partly because trivial points of effort (friction costs) have a disproportionate impact and undermine our good intentions. For example, we’re less likely to start cycling to work if our bike has had a flat tire since last summer, despite our good intentions and the relative ease of fixing it. These upfront frictions are felt particularly strongly, relative to the long-term consequences, due to our tendency to steeply discount the future (present bias) (Laibson 1997). And so, even if cycling to work could save us a lot of money in the long run, the upfront effort of spending five minutes pumping up the tire may still deter us. Similar barriers exist to the adoption of attic insulation, which require us to clear out our old junk and memories (DECC 2013)—many of us therefore never get around to making these energy efficiency improvements despite good intentions and knowledge of the long-term economic benefits.

And it’s not just these conscious decisions that are subject to inertia. A lot of our behavior is habitual and automatic. The way we use water when showering or brushing our teeth, the way we travel to work, and what we do with leftover food are all so routine that we have automatic responses to these situations. In this case, we must disrupt those routines before we can expect to instill new behaviors.

Solutions: All of the above factors lead to behavioral inertia. But there are a number of ways to crack these patterns and routines, overcome procrastination, status quo bias, or present bias and perhaps establish new lasting habits. Consider these possible strategies:

• Front-loading benefits or incentives to leverage our present bias. By bringing the benefits into the present, and pushing costs or effort into the future, we can increase the motivation to act. For instance, this could include interest-free loans for homeowners to install insulation now, gaining warmth and lower bills immediately but paying later. The same could be done for electric cars, which otherwise tend to be more costly upfront (discouraging purchase) despite being cheaper over the long run.
• Precommitments. A different approach to addressing our present bias is to ask people to precommit to future good acts they may not do in the present. For example, just as committing to running a marathon next year is much easier than running a marathon today, preordering healthy or sustainable food is easier than choosing it in the moment (and thus preordering increases the portion of people choosing healthy options) (Miller et al. 2016). Such precommitments, large and small, can help lock us into better choices in future.
• Removing frictions to make the behavior easy. We tend to follow the path of least resistance, and so removing small barriers to the more desirable choices can be a powerful force for change. Conversely, adding in small frictions can discourage the unsustainable status quo. For instance, studies have shown that removing the plastic trays from a canteen can significantly reduce food waste by making it slightly more difficult to take too much food the first time around (Thiagarajah and Getty 2013).
• Identifying or creating timely moments. We are much more likely to change our behavior when habits and routines are either not yet established or momentarily disrupted. For example, we are more likely to make energy efficiency improvements to our house when we have just moved in (when redecoration is happening anyway and the attic isn’t yet full of junk). A study in Portland, Oregon, similarly found that new residents were four times more likely to adopt a cycle-sharing scheme compared to those who already lived in the area (Kirkman 2019). These one-time decisions often having lasting impacts, and so identifying these timely moments, when we are most open to being nudged into a new trajectory, is key.

Consistency Effects: Motivated Reasoning, Confirmation Bias, and Escalation of Commitment

The challenge: It is intuitive to assume that our attitudes and beliefs drive our behaviors. In part they do, but the opposite is also true: we take certain actions for a variety of reasons (perhaps automatically, or because they are convenient or profitable), and then subsequently adopt attitudes and beliefs which “explain” that behavior in a positive light. This is driven by a powerful need for a consistent but ego-enhancing narrative of our own lives and the world around us. For example, we may start cycling to work because we live in a city and can’t afford a car. But cycling to work causes (or at least enables) us to adopt a stronger proenvironmental identity and value system—one more reason to feel virtuous.

We achieve this bait-and-switch through a range of psychological tricks including motivated reasoning (using reason to justify the convenient or flattering conclusion, not the logical one), moral licensing (using one good act, such as recycling, to excuse ourselves another, such as flying on vacation), and confirmation bias (a tendency to seek out and recall information that confirms our prior views or justifies our decisions over information that discredits them).

These phenomena can lead to a form of behavioral lock-in because of the tendency to justify and thus double-down on past decisions and actions. When we act against our green values by continuing to fly on vacation or eat unsustainable diets, our ability to rationalize and justify that behavior not only shields our conscience from guilt and cognitive dissonance but also renders us less likely to change our behavior going forward. This logic applies to a wide range of environmentally unsustainable behaviors (Druckman and McGrath 2019), but it has also been studied in the consumption of animal products (Graça et al. 2016) and the purchase of fashion produced in sweatshops (Paharia  et al. 2013)—all cases where consumers’ behavior diverges profoundly from their purported values.

Solutions: The key driver of the tendency to rationalize our actions, and thus lock in patterns of behavior, is to avoid feelings of guilt, inconsistency, or cognitive dissonance. Changing hearts and minds therefore requires more tact, through strategies like the following:

• Harness pride rather than guilt. Guilt is commonly used in environmental campaigns and can motivate behavior change where change is easy. But intuitively, if we’re admonished for choices and habits that we’d rather not give up, our natural response is to defend ourselves and justify our actions, and in doing so perpetuate them (Diekmann and Preisendörfer 2003). It therefore stands to reason, and research has shown, that messages of pride at what is being done and what more can be done can be more effective at motivating behavior change (Schneider et al. 2017).
• Framing. We can also achieve some benefits by carefully framing the issue so that it aligns with an individual’s self-interest or existing worldview to avoid this tension altogether. Put simply, why try to fundamentally change someone’s values if we can promote sustainable choices through their existing values? A fabricated example illustrates this point: while those on the political left in the United States may base their support for local renewable energy generation on environmental grounds, those with different values may be inclined toward arguments of economic growth or energy independence. The environment need not be mentioned at all.

Research on moral foundations theory further suggests that the political Left tends to emphasize morals of harm and fairness (which is the usual basis of environmental “justice” arguments), whereas those on the right also build their morality on a sense of sanctity and purity (which is related to the powerful emotion of disgust) (Haidt 2012). Notions of cleanliness and purity might therefore be more effectively harnessed to promote the protection of oceans and waterways from pollution, for example, when targeting certain political groups.

Social Contagion

The challenge: We are deeply social creatures and tend to adopt the behaviors of those around us, particularly those “like us” with whom we share a social identity. This is in part a process of peer pressure (normative social influence) and partly the aforementioned process of social proof (informational social influence) by which we use the behavior of others as a source of valuable information—it implies what is safe, what is sensible, or advantageous. This is why solar panels have proved to be contagious (Plumer 2015)—if other houses around you have chosen to buy them, we infer our neighbors might be on to something.

Clearly, social contagion can be a force for rapid change, good or bad, though this is rarely predictable. However, it can also lock society into certain pathways and norms, because the pressure to conform can be strong, and our perception of what is possible or acceptable can become narrowed by pervasive norms.

The solution: Our social nature is also part of the solution. For example, we can promote sustainable behaviors simply by emphasizing existing or emergent norms where they exist. We often have incorrect perceptions of what is “normal,” and so being told, for example, that “many other people are reducing their meat consumption,” or “most other hotel guests reuse their towel,” significantly increases the number who choose to follow suit, typically more so than with conventional proenvironmental messaging (Sparkman and Walton 2017; Baca-Motes et al. 2012). Similarly, studies have shown that telling people they use more energy than their neighbors leads to reduced energy consumption (Alcott 2011).

The power of conformity is particularly important in addressing potential tragedies of the commons, such as fishery depletion, deforestation, or greenhouse gas emissions. Here we require cooperation—if all parties do the right thing (e.g., stick to quotas) everyone will be better off, yet it is in any one individual’s interest to cheat or take more than his or her share. In these cases economic tools such as fines, regulation, or resource privatization can be highly effective, since they align personal self-interest with the protection of the resource in question. However, it can also be effective to promote cooperation and collective action through social norms and reciprocity. Simply put, we are more likely to act in the collective good if we know others are also doing so (due to our tendency to reciprocate) and if there is increased observability and accountability of our actions to the wider group (due to our tendency to succumb to peer pressure). Communicating the high prevalence of good behavior (i.e., highlighting that transgression is not the norm, or acceptable) and building systems of observability (e.g., by introducing reporting standards or league tables of environmental performance) can therefore be effective interventions: a form of regulation by reputation.

The Next Frontier for Behavioral Science: Tapping into Market Forces to Unlock Bigger Changes

Many of the above strategies seek to promote individual behavior change, through a range of tools that target the psychological, social, and physical determinants of our actions. While this is critical, we must also seek bigger levers we can pull to more fundamentally alter markets, and thus lock society into more sustainable outcomes. These include carbon taxes and regulation. However, where governments are unable or unwilling to act so robustly, modest behaviorally informed interventions can also lead to bigger systemic change.

For example, consider a carbon tax on high-emissions food such as red meat and dairy. A conventional Pigouvian tax on these products (such as introducing a higher rate of sales tax) would increase the cost of these products and therefore cause a proportion of consumers to reduce their consumption. While successful on its own terms, this approach may be regressive, impacting low-income households the most, and will only impact the fraction of consumers who respond to the price increase. Consider instead a tax that kicks in only above a certain CO₂-per-portion threshold, with that CO₂ threshold deliberately set so that suppliers can avoid the tax by modestly reformulating their products (e.g., seeking more efficient production methods, or by blending in different ingredients). The threat of a fraction of consumers’ switching to another brand to save money would incentivize product reformulation among competitive producers wishing to maintain market share. The consequence is that prices do not increase because the tax is never collected; consumers do not need to change their behavior (they buy the same products, often unaware they have been reformulated); and all consumers of those products reduce their carbon footprint, even the most inert ones who wouldn’t have changed their behavior in response to the tax. Continued reductions over time in the carbon threshold at which the tax applies could continue to incentivize environmental improvements throughout the producers’ supply chain.

The power of this approach is that we are not trying to get consumers to make different choices within the existing choice set but are instead nudging producers to create a different choice set for consumers, which has a greater impact across the sector. This is achieved by first nudging a small number of consumers (with the tax), explicitly to realign market incentives in order to nudge producers. This “double nudge” is the exact design of the United Kingdom’s recently introduced levy on high-sugar drinks, which drove mass reformulation and led to a 26 percent reduction in sugar intake without reducing sales.

Ultimately, focusing solely on consumers, and encouraging them to change their choices without altering the choice environment around them, will bring some benefits but will not lock society into sustainability-by-default. We must also nudge markets and systems in these and other ways if we wish to steer the forces of economics and innovation toward more sustainable outcomes, and keep them there.

References

Allcott, H. 2011. “Social Norms and Energy Conservation.” Journal of Public Economics 95 (9–10): 1082–95.

Baca-Motes, K., A. Brown, A. Gneezy, E.A. Keenan, and L.D. Nelson. 2012. “Commitment and Behavior Change: Evidence from the Field.” Journal of Consumer Research 39 (5): 1070–84.

DECC (Department of Energy and Climate Change). 2013. “Removing the Hassle Factor Associated with Loft Insulation: Results of a Behavioural Trial.” London: DECC. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/236858/DECC_loft_clearance_trial_report_final.pdf.

Diekmann, A., and P. Preisendörfer. 2003. “Green and Greenback: The Behavioral Effects of Environmental Attitudes in Low-Cost and High-Cost Situations.” Rationality and Society 15 (4): 441–72.

Druckman, J.N., and M.C. McGrath. 2019. “The Evidence for Motivated Reasoning in Climate Change Preference Formation.” Nature Climate Change 9 (2): 111–19.

DWP (Department for Work and Pensions). 2017. Automatic Enrolment Review 2017: Maintaining the Momentum. London: DWP.

Dolan, P., M. Hallsworth, D. Halpern, D. King, and I. Vlaev. 2010. MINDSPACE: Influencing Behaviour for Public Policy. London: Institute for Government.

Ebeling, F., and S. Lotz. 2015. “Domestic Uptake of Green Energy Promoted by Opt-Out Tariffs.” Nature Climate Change 5 (9): 868–71.

Graça, J., M.M. Calheiros, and A. Oliveira. 2016. “Situating Moral Disengagement: Motivated Reasoning in Meat Consumption and Substitution.” Personality and Individual Differences 90: 353–64.

Haidt, J. 2012. The Righteous Mind: Why Good People Are Divided by Politics and Religion. London: Allen Lane.

Kirkman, E. 2019. “Free Riding or Discounted Riding? How the Framing of a Bike Share Offer Impacts Offer-Redemption.” Journal of Behavioral Public Administration 2 (2). doi.org/10.30636/jbpa.22.83.

Laibson, D. 1997. “Golden Eggs and Hyperbolic Discounting.” Quarterly Journal of Economics 112 (2): 443–78.

Miller, G.F., S. Gupta, J.D. Kropp, K.A. Grogan, and A. Mathews. 2016. “The Effects of Pre-ordering and Behavioral Nudges on National School Lunch Program Participants’ Food Item Selection.” Journal of Economic Psychology 55: 4–16.

Paharia, N., K.D. Vohs, and R. Deshpandé. 2013. “Sweatshop Labor Is Wrong unless The Shoes Are Cute: Cognition Can Both Help and Hurt Moral Motivated Reasoning.” Organizational Behavior and Human Decision Processes 121 (1): 81–88.

Plumer, B. 2015. “Solar Power Is Contagious: Installing Panels Often Means Your Neighbors Will Too.” Vox, April 1. https://www.vox.com/2014/10/24/7059995/solar-power-is-contagious-neighbor-effects-panels-installation.

Schneider, C R., L. Zaval, E.U. Weber, and E.M. Markowitz. 2017. “The Influence of Anticipated Pride and Guilt on Pro-environmental Decision Making.” PLOS One 12 (11): e0188781.

Sparkman, G., and G.M. Walton. 2017. “Dynamic Norms Promote Sustainable Behavior, even if It Is Counternormative.” Psychological Science 28 (11): 1663–74.

Thiagarajah, K., and V.M. Getty. 2013. “Impact on Plate Waste of Switching from a Tray to a Trayless Delivery System in a University Dining Hall and Employee Response to the Switch.” Journal of the Academy of Nutrition and Dietetics 113 (1): 141–45.

Tversky, A., and D. Kahneman. 1991. “Loss Aversion in Riskless Choice: A Reference-Dependent Model.” Quarterly Journal of Economics 106 (4): 1039–61.

¹ For a discussion of this, and a nice example on congestion charges, see Dolan et al. (2010).