Guest post: How human behaviour shapes effective climate policies

There is clear evidence that technological change will be insufficient to meet UK and global climate goals on its own, leaving a vital role for consumer and business behaviour change.

Indeed, most measures to reach net-zero emissions by mid-century will require at least some behaviour change by the public.

This includes reducing car use, changing diets to eat less red meat and dairy, cutting waste and buying electric vehicles and heat pumps. 

The scale of change is profound: limiting warming to 1.5C would mean reducing the average European carbon footprint from 7.5 tonnes of carbon dioxide equivalent (tCO2e) to 2.8tCO2e per person by 2030.

Behaviour change is also required to adapt to climate risks, such as flooding, drought and heat stress, our research shows.

This includes emergency and long-term behavioural responses, such as evacuation, buying insurance and installing equipment. 

However, policies to deliver these behaviour changes are currently lacking in the UK.

In 2023, a House of Lords inquiry concluded that the government’s approach to enabling behaviour change for climate and environmental goals was “seriously inadequate”. 

The Skidmore review of net-zero, also published in 2023, similarly concluded that more government action is needed to support behaviour change and advocated a public-engagement strategy to deliver this.

More recently, in a major review for the Climate Change Committee (CCC), my co-authors and I outlined what behavioural science can tell us about how to deliver effective climate policy.

We found that, in general, wider social or practical factors – such as norms, functionality and price – tend to be more influential for encouraging low-carbon behaviours than an individual’s knowledge, values and emotions.

How to change behaviour

There is a sizeable evidence base on how to deliver low-carbon and climate-resilient lifestyles and on changing behaviour in professional contexts. 

Using literature searches and a call for evidence, identifying almost 400 sources in total, we examined evidence for what works to change behaviour within eight main areas: 

• diet 
• consumption 
• aviation
• adaptation
• net-zero skills and careers
• business leaders and the transition to sustainability 
• land use and farming 
• policy acceptability

Numerous behavioural theories and models exist to explain and predict climate mitigation and adaptation actions. 

Psychological theories, such as the theory of planned behaviour (TPB) and the value-belief-norm model (VBN) assume action is primarily driven by internal factors, such as attitudes, values and knowledge. 

Specifically, the TPB states that behaviour results from intentions, which, in turn, are the outcome of attitudes, perceptions of social norms and ability.

The VBN sees behaviour as the outcome of a sequence of values, which informs beliefs and perceived responsibility for environmental problems, which shapes the moral obligation to act, leading to action. 

Since the TPB includes perceived ability, acknowledging external social, physical and economic factors can limit or propel action. Research suggests it does better than the VBN at explaining higher-impact environmental behaviours, such as avoiding driving, than lower-impact behaviours that tend to be more within individuals’ control, such as recycling.

In contrast, sociological theories – such as social practice theory – tend to place more emphasis on the contextual drivers of action, such as physical infrastructure and social conventions.

Social practice theory sees practices – such as showering or cooking – as resulting from the interaction of physical and technological factors, social conventions and skills. These also see action as routine or habitual more often than intentional. 

Integrative models also exist that draw on various theories to explain behaviour. One of the most commonly used is the COM-B model, which identifies capabilities, opportunities and motivations as the key drivers of behaviour.

Our review found that, in general, low-carbon and climate-resilient behaviours are driven by both internal and external factors, including: 

1. Individual knowledge, values and emotions.
2. Social factors, such as norms and group identity.
3. Practical factors, such as functionality, ease and price. 

Of these various drivers, individual factors – such as knowledge – tend to be less influential in changing behaviour than wider social or practical factors. 

Consequently, interventions targeting individual decision-making or motivation, such as information provision, tend to be less effective than interventions targeting the context of action. These interventions, such as regulations, incentives and infrastructure changes, typically make behaviour easy, attractive and normal – or even the default.

One review found that informational approaches, such as labelling or in-home displays, were on average only 3% effective. In contrast, “nudges” that adjust choice environments to make sustainable choices easier, but without coercion, were, on average, 25% effective. 

These nudges could include locating recycling bins closer than regular waste bins or putting energy consumers on green tariffs (instead of fossil fuel tariffs) by default. 

Individual-focused interventions, such as information provision (e.g. campaigns), are known as “downstream” measures, while context-focused interventions, such as nudges, economic measures and regulation, are “upstream” measures. 

Despite evidence of its limited efficacy and tendency to exacerbate inequalities, there is a preference amongst policymakers for downstream over upstream interventions. 

This is, in part, because the former is more easily experimentally tested and costed, but it is also due to power structures in government, political ideology and skills gaps.

Targeted and timely change

Beyond targeting upstream changes, our review also found that interventions are more effective when they are: 

• Targeted – to the specific needs and abilities of different groups. 
• Combined – that is, they include downstream and upstream approaches, as well as addressing the multiple behavioural drivers and barriers. 
• Timed – to when habits are malleable, such as household renovation or relocation, or when business leaders or farmers are making key investment decisions. (In psychology, this is termed “habit discontinuity”.)

Public engagement is also important for effective behaviour change interventions to both foster acceptance and address contextual factors or constraints to efficacy, our research suggests. 

Interventions to change behaviour that are imposed on people without consultation risk being rejected, as seen with the “Gilets Jaunes” in France and London’s Ultra low emission zone (Ulez) expansion protests. Bringing the public into decision-making from the outset to scope a problem and identify solutions is more likely to lead to fairer and more acceptable outcomes. 

Climate assemblies and juries are examples of how this is increasingly being achieved. Engagement can also help communicate the need for and benefits of climate action and therefore promote policy acceptance.

From our research over the years at the Centre for Climate Change and Social Transformations (CAST), we know that different approaches work better depending on the sector.

For example, adaptation behaviour change requires a stronger focus on information provision than mitigation actions, since there is little public awareness of why or how to adapt to climate risks. 

For transport, congestion charging and reallocating road space from cars to less polluting modes – such as pedestrianisation and low-traffic neighbourhoods – are amongst the most effective ways of cutting car use. Additionally, frequent flyer levies enjoy public support so may be a fair and effective way of curbing aviation growth. 

But, in both cases, there is a need for “carrots” as well as “sticks”. Alternatives to driving and flying must also be convenient, affordable and attractive if people are to switch to these lower-carbon modes, our research found. 

For diet change, communicating the various benefits of low-carbon diets and carbon labelling – for health and the environment – has some effect. However, our research suggests lowering the price of vegetarian options and making them more available – including the default option – is far more effective. 

In one simple, but effective, study, researchers doubled the proportion of vegetarian meals available in canteens – from one-in-four, to two-in-four options. This led to increases in vegetarian meal sales of up to 79%. 

But there are still gaps in the evidence base. Little is known, for example, about how to encourage people to adopt climate-resilient behaviours or to reduce flying. More generally, we found little evaluation of real-world interventions. 

Removing barriers

Our review concludes with core recommendations for using behavioural science in climate policy. These include identifying behavioural targets – for example, based on carbon impact and feasibility – engaging with the public and combining, timing and tailoring interventions.

While there are evidence gaps, our research shows that much is already known about how to foster low-carbon, climate-resilient behaviour change. 

Moreover, the public wants to play their part in tackling climate change. Public concern about climate change has not been reduced by Covid-19 or the cost-of-living crisis – and most people in the UK and around the world agree that individual behaviour change is needed. 

We found that the government now needs to use these insights from behavioural science to remove the barriers to behaviour change. This, in turn, will help accelerate the net-zero transition and adapt to climate risks.