Anthropogenic climate change is a global concern. However, that climate change concerns all of us does not mean that it would concern all of us equally. Income is the primary correlate of carbon footprint whether analysed on a national or individual level. The richest half of the world’s countries (in GDP) emit 86% of global CO2 emissions. The difference is even starker when analysed on an individual level: income level is also the strongest correlate with citizen CO2 footprint (2016 data from the Global Carbon Project). The effect of attempts to decrease carbon footprint in wealthy countries by producing climate-friendly consumer goods, energy, and transport options have had limited effect – in part because these only transform a small part of citizens’ total consumption behaviour, and in part because reductions are needed, primarily, in the amount of consumption by high-income citizens rather than in the specific goods being consumed.

Additionally, there are regional patterns in the effects of the climate change, which together with the fact that low-income countries and individuals have less means to prepare or adapt to the effects of climate change entail that the harms resulting from anthropogenic climate change are also not equally distributed. As a result, the climate crisis is a global justice concern.

Climate action is needed, and a wealth of climate policies have been implemented and proposed. No single policy, but rather a range of complementary global and local policies, are needed to sufficiently address the climate crisis. In this blog post, I raise some preliminary thoughts on behavioural climate policy, specifically. There is a tension between the localized character of nudges and the broad, global impacts sought. In light of the global impacts sought, it seems to me that efficiency and scalability become primary considerations for climate nudges.

Behavioural public policy beyond paternalism

Behavioural public policy is the application of non-coercive interventions informed by the behavioural sciences (e.g., psychology and behavioural economics) to steer citizen behaviour. For example, nudges steer citizen behaviour by altering the environment in which citizens make choices, rather than via economic incentives or rules and regulations, without foreclosing any of the alternatives available to citizens. A classic example of a nudge, laying out food in cafeterias with vegetarian options first, causes customers to load their plates with vegetables and to eat less meat. The most efficient nudges, however, are default nudges – policies based on making sure that what happens if you do nothing is beneficent or otherwise desirable. For example, instead of citizens needing to enrol in pension savings plans or sign up as organ donors, they can be enrolled by default, and can opt out from the scheme at any time. The terms ‘behavioural climate policy’ and ‘climate nudge’, in what follows, refer to the application of behavioural public policy and of nudges to climate policy.

In Nudge: Improving Decisions About Health, Wealth and Happiness (Penguin 2008), Sunstein and Thaler sell nudging as founded on “libertarian paternalism”, which in their view entails non-coercive paternalistic measures. For the paternalist analysis of nudges, the benefits of nudges chiefly fall on the persons being nudged. Consequentially, much of the ethical discussion around nudging has concerned debates surrounding the permissibility of paternalist policy, whether nudges indeed are non-coercive, and the issue of how to address local justice in nudge development: if the benefits of a nudge fall on the people being nudged, a nudge that is most effective in a middle-class population will fail to benefit those who are worse off.

While the paternalist analysis is well suited for nudges that target health behaviours or pension savings plans, it is a poor fit for nudges for which the benefits do not primarily fall on the person being nudged. As a result, only some nudges lend themselves to Thaler and Sunstein’s libertarian paternalist characterization. For example, for the organ donation default nudge, the nudge is very unlikely to benefit the donor in any sense. Although we are collectively better off with a larger pool of donors, the prospected benefit for each individual citizen is very slim (the value of receiving an organ multiplied with the odds of that being the case). Likewise for climate nudges. For successful climate nudges, the altered behaviour falls on a local population, whereas the benefits of decreased emissions are a common good. Although the collective benefit, if successful, is significant, the benefit for individual citizens is very small. As a result, the local justice considerations for climate nudges are not analogous to those of health or savings nudges.

Since the primary aim of climate nudges is a common good, assessing the local justice considerations of climate nudges should focus on their externalities, that is, the various side effects the nudge has. For example, nudges promoting a climate-friendly diet or bicycling to work also tend to promote health, whereas nudges for switching to green energy incur no benefit for the person being nudged. In considering these, as well as any potential costs of nudges, the impact on the target population, particularly on the less well off, ought to be given due consideration.

Climate nudges: too localized for the common good?

Climate nudges purport to be one tool among many for resolving a global crisis. However, the modus operandi of nudges, namely that they work by altering citizens’ choice architecture – i.e., their ecological decision-making – makes nudging a highly localized choice of policy. First, nudges are always implemented locally: it is always a given local population whose behaviour is in practice impacted by the policy. Second, nudge development needs to be responsive to features of the local built and social environment in order to be effective. Nudges that work well in small towns may not work in metropolises, and GDP-related features such as resources available have an impact on which nudges are feasible in a given context.

In the literature on the ethics of nudging, often, the relevant ethical contrast is drawn between the presence of a nudge and the presence of no nudge (i.e., when the choice architecture has not been purposefully altered to steer citizen choices).

However, when we shift our focus to the global scale of the climate crisis, this is not the only relevant contrast. While the implementation of nudges is typically very cost-effective, the development of effective and ethically sustainable nudges is a process requiring expert labour and other cost-intensive resources. In the case of a global crisis, such as the climate crisis, we ought to also consider the contrast between developing nudges and using those development resources for other strategies.

In terms of climate justice, the ‘polluter pays’ principle as well as global equity suggest that wealthy countries should bear the largest burden in climate change mitigation. From a global justice perspective, nudging local populations in wealthy countries is well justified, if it is an efficient use of resources. If not, then wealthy countries should seek to shoulder their burden in climate change mitigation by more efficient means. Climate nudges can be an example of acting locally while thinking globally, but if efficiency is not duly considered, they can end up a technocratic form of greenwashing.

Almost all nudges, given that they’re deployed locally, have relatively small effects on the climate crisis – even if the effect size is large, which it often is not. As a result, scalability should be the first concern in developing climate nudges. The developed intervention should be one that can potentially be adopted far and wide, rather than only in its location of development. (A plausible exception is metropolitan areas, where the nudge, even if local, may already concern tens of millions of people.) One source of optimism here is that over half of the world’s population live in medium-sized towns and cities (i.e. neither rural nor metropolitan). The most scalable nudges, then, would target the many similarities in transport, energy use, and other consumption choices between medium-sized towns and cities in wealthy countries.

Should climate nudges be deployed in countries that are not among the worst polluters? Prima facie, it seems that climate nudges are permissible whenever there are climate-friendlier alternatives that citizens are not taking that do not incur unjust externalities. In many low-GDP countries, many of the nudges that work well in wealthy countries may be unnecessary (as people already eat less meat or commute by bicycle or foot), there might not be a realistic climate friendlier alternative (e.g., green energy is not available or is prohibitively costly for a large portion of the population), or the externalities incurred are not justified. There is also a real risk of causing harm out of ignorance or self-importance. To quote Teju Cole, “The white savior supports brutal policies in the morning, founds charities in the afternoon, and receives awards in the evening.” However, while nudge development in low-GDP countries requires epistemic humility and sensitivity to the local realities, dismissing the prospects of altering large-scale citizen choices in low-GDP countries out of hand would risk being dismissive of the political agency of citizens in these countries. These worries underscore the need to involve local political actors, stakeholders, and experts in nudge development.

To conclude these tentative thoughts, climate nudges ought to be contrasted not just with the no-nudge alternative, but also with other alternative strategies and policy measures. Attention needs to be paid to externalities, as well as to efficiency. Given that for nudges efficiency comes with scalability, in my current view the scalability of interventions should be a priority in behavioural climate policy.

I am a Senior Researcher in ethics in the Nudging for Climate research consortium, at the University of Turku, Finland. My chief philosophical interests are agency and self-control, psychiatry, neuroethics, and behavioural policy.