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We Don’t Have Time founder Ingmar Rentzhog explains why dialogue and understanding are key to climate action.
2 May 2025
A critical vision of life after climate action looks like vegans riding bikes, city centres without cars and people giving up air travel.
But a paper published in Nature Sustainability finds that climate policies targeting lifestyle changes (such as urban car bans) may actually weaken people’s green values, thereby undermining support for other needed environmental policies.
Katrin Schmelz, a behavioural economist and psychologist who also holds an Associate Professorship at the Technical University of Denmark, began gathering data while at the University of Konstanz in Germany.
Along with SFI Professor and economist Sam Bowles, she surveyed more than 3,000 Germans representative of the country’s demographics, asking about climate policies and, for comparison, Covid-19 policies.
The survey yielded evidence that well-intended but poorly designed mandates can make even ‘green’ citizens less green.
‘Policies don’t just spur a target behaviour. We find that they can change people’s underlying values: leading to unintended negative effects, but also possibly cultivating green values.’
KATRIN SCHMELZ
Lead author, SFI Complexity Postdoctoral Fellow
Restrictions that promote carbon-neutral behaviour, such as urban car bans, may trigger strong negative reactions – even among people who would voluntarily choose sustainable lifestyles.
This erosion of existing values is a clear example of what’s known in psychology and economics as the ‘crowding-out effect’.
‘These crowding-out effects are big enough that policymakers should worry.’
SAM BOWLES
SFI Professor and economist
A person’s aversion to control ‘crowds out’ their pre-existing motivation to follow a green lifestyle – for example, riding their bike, walking and taking public transport or being more mindful when heating or cooling their home.
Another key finding, which surprised the authors, was a 52% greater negative response to climate mandates than to Covid-19 mandates.
‘We saw incredible hostility in the US and other countries towards controls during the Covid-19 pandemic, hindering the implementation of much-needed public policies. It looks like the climate case could be much worse. The science and technology to provide a low-carbon way of life is nearly solved. What’s lagging behind is a social–behavioural science of effective and politically viable climate policies.’
SAM BOWLES
SFI Professor and economist
The research Schmelz and Bowles have begun is already seeing applications. Last April, policy experts and researchers from various disciplines met at SFI to discuss preliminary findings from the study and brainstorm how to design policy that can encourage green values.
There is reason for optimism, the study shows. Mandate resistance was less for people who felt that policies were effective, didn’t restrict their freedom of choice and were not intrusive on their privacy or their body.
‘We found three conditions that minimise opposition to mandates, and may even cultivate, rather than crowd out, green values.
‘People are more open to policies that they think are effective (in reducing CO2 emissions), and that they don’t perceive as privacy-intrusive. People also respond much more positively if they don’t feel that a policy restricts their freedom – so in Germany, there is less opposition to limitations on short-haul flights compared to other policies, and this may be because the European train network provides an adequate alternative (which may not be the case in the USA, for example).’
KATRIN SCHMELZ
Lead author, SFI Complexity Postdoctoral Fellow
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