This research analyses the active support of people living in Spain for three potential policies for combating climate change:

1. Prohibition of the use of polluting light-duty vehicles from 2029,

2. a discount of 10% on water bills for those households that reduce their water consumption, and

3. a tax on carbon, implemented through eight alternative designs.

Climate change has become a major concern worldwide. The evidence compiled by the National Aeronautics and Space Administration (NASA) of the United States reveals that global warming is currently advancing approximately ten times faster than the average rate of warming that occurred following the last ice age.

Because of its economic structure and biodiversity, Spain is especially vulnerable to the effects of climate change. Increases in temperature can cause a very significant reduction in water resources, acceleration of the desertification of a large part of the territory and a reduction in the productivity of the fishing and agrarian sectors. Furthermore, the foreseeable increase in sea levels arising from these environmental factors could compromise some of the most popular tourist destinations on the Peninsula, such as Marbella or Barcelona. Therefore, with this scenario in sight, taking action on measures oriented towards adapting the country to the consequences of climate change should be a priority at all levels.

Despite this, the success of any strategic plan in the face of a social challenge of this size is dependent, ultimately, on the support it is given by citizens. Some 78% of Spaniards believe that human action has an important influence on climate change, and around 90% believe that this phenomenon means a change in our societies is required. Despite this, support for specific climate change policies that aim to modify individual behaviour is significantly lower.

For example, only 59% of Spaniards have reduced their water and energy consumption over the last year. In order to expand this base of citizens who are committed to sustainability – and, therefore, willing to make changes in their behaviour or, alternatively, give support to actions, even if doing so may affect them personally – it is essential to understand what factors influence citizen support for climate change policies. Only in this way will it be possible to improve the design of these actions and increase their possibilities of success.

This study consists of two parts. The first analyses the five factors that, foreseeably, affect the degree of support from citizens for actions and policies designed to combat the effects of climate change. These factors are as follows:

1. The perceived effectiveness of the policy or action;

2. the self-perceived individual responsibility for acting against climate change;

3. a person’s self-perceived capacity to change his or her behaviour;

4. resistance to change, and

5. the distance with which people perceive climate change.

The study focuses on active support (for example, voting in a referendum in favour of the implementation of a certain environmental measure) for two policies that could be applied on a nationwide scale:

• A measure relating to cars: the banning in Spain, by 2029, of cars that emit CO2, and

• a political action focusing on the consumption of water: applying discount of up to 10% on water bills for households that reduce their consumption by at least 10% in comparison with the previous year.

The data were analysed using a statistical model that enables estimation of the specific causal effects for each of the five factors of interest (in other words, isolating the effect of each factor, so that it cannot be confused with the effects of other factors). Furthermore, the model takes into account the fact that the effects may be different for different classes of people; in particular, those who are directly affected by the introduction of the measure (in other words, in our case, those who have a vehicle affected by the ban, or consume a quantity of water above real needs, which could enable consumption to be reduced) in comparison with those who are not.

Firstly, it is important to mention that the level of support for each one of the policies analysed is quite different: while only a third of those surveyed give active support to the measure of banning cars that emit CO2 by 2029, in the case of the water measure the support rate is multiplied by two, reaching two thirds. One initial conclusion, therefore, is that the support of citizens for measures against climate change depends significantly on the type of measure proposed, independently of whether they directly affect the person asked or not.

Apart from this first consideration of the impact of the type of measure on the support that citizens would lend, analysis of the five factors highlights some interesting elements regarding designing effective public policies.

Specifically, the data show that:

• The strongest positive effect on citizen support for the measures occurs when people consider them to be effective.

In fact, the most important factor is people’s perception of the measure’s effectiveness: the higher its perceived effectiveness, the higher the active support that it receives.

Although this effect is even higher when citizens do not feel directly affected by the measure, the analysis suggests that, even in cases where the measure brings with it an important change in habits, the effectiveness logic is maintained: the more probable it is, according to citizens’ perceptions, that the measure will effectively achieve the goals it pursues (for example, reducing CO2 emissions or water consumption), the higher the support for the initiative.

• It is more likely that measures will receive support from people who feel responsible for taking action against climate change.

Thus, the more responsible a person feels and the more compelled to take action against climate change, the greater the support that person gives to policies geared towards fighting it. This effect is small in the two measures analysed, whether people are affected directly by the measure or not.

• People’s self-perceived capacity to change their own behaviour has a positive effect, but only on the level of the support they give to the measure relating to cars.

As we would expect, people who feel more capable of changing their habits – with the aim of complying with the demands derived from a specific policy measure – accredit a higher degree of support for the measure although, in this case, only for the measure relating to banning cars that emit CO2 by 2029. This effect is not detected for the measure relating to water.

One possible explanation for this divergence could be that the measure relating to water aims to adjust a behaviour (in this case, the pattern of water consumption of Spaniards) to a future situation (scarcity of water resources as a consequence of climate change). These policies of adjustment or adaptation are viewed, generally, to be the responsibility of government authorities, which should adapt the country’s infrastructures to the new situation, a process in which citizens would be involved only passively. The result of this view is that it minimises the role that personal effectiveness plays in people’s opinion when it comes to deciding whether or not to give support to the initiative.

• The level of resistance of individuals to making changes in their lives is a factor that also affects their support to the measure relating to cars.

Contrarily, people’s resistance to any kind of change has no effect on the degree of support that they show for the measure relating to water. This result could be explained by the fact that adaptation policies, as we have seen in the previous section, are associated in general with weaker efforts on an individual scale. In addition, the measure analysed in this case is based on the use of incentives; thus, a “prize” (discount on the water bill), compensates the individual effort that is represented by reducing its consumption.

In contrast, with regard to the measure relating to cars, the people who are most resistant to any kind of change are slightly more likely to give it support. This surprising result could be explained because people perceive a certain compensation between the current demand of a small change (not using the polluting car), against the future demand of greater changes, deriving from the severe impacts of climate change in Spain.

• The distance with which citizens perceive the effects of climate change has varying effects on the degree of support for the measures.

In contrast with what we could expect, the distance with which people perceive the effects of climate change does not have a direct effect on the degree of support for the measure relating to polluting vehicles, and only a slightly negative effect on the measure relating to water consumption (in other words, people who do not believe in the pernicious effects of climate change or that, despite accepting them, think they will not be affected personally by them, give slightly lower support to the water measure).

The distance with which people perceive the negative effects of climate change affects two further factors: the perceived effectiveness of the measures and the perceived degree of individual responsibility for taking action against climate change. Thus, the more distant the effects of climate change are seen to be, the lower the perceived effectiveness of the measures and the lower, too, the feeling of individual responsibility.

In short, although the direct effect of the distance with which the negative effects of climate change are perceived is negligible or low, there are two indirect effects that intervene in the equation: the perceived effectiveness of the measure and personal responsibility with regard to climate change. Thus, the global causative effect of this factor in the degree of support for the measures is considerable and its importance cannot be denied.

The second part of this study analyses to what point Spaniards would be willing to give support to a policy which would tax emissions of CO2.

For this, a hypothetical scenario was proposed to respondents in which a referendum was called to put the decision regarding whether to implement a tax related to emission of this gas in the hands of citizens.

For this purpose, an experiment was conducted to check to what point the way in which the question was written conditioned the answer (for example, in one case the term tax was used and, in the other, the word price). Also put to the test was whether allocating monies collected through this tax to diverse uses had, in each case, an equally diverse effect on the perception of the fair nature of the tax, of its effectiveness, and on the level of support for the measure from the person being surveyed.

Thus, four scenarios were proposed, one in which no information was given on the uses allocated to the monies collected, one that stated that the funds collected with the measure would be allocated to starting up and maintaining environmental conservation programmes, another in which these funds would additionally serve to offset the taxes paid by families with fewer resources, and a final one in which the funds obtained would help reduce other taxes.

The results obtained indicate that the Spanish would give support to a possible tax on CO2 emissions on two conditions: firstly, that the measure would have a social character, in other words, it would affect citizens differently according to their socioeconomic level, and secondly, that it would be combined with the possibility of reducing other taxes of a general nature. In contrast to research carried out in other countries, the fact that the funds served to implement environmental policies did not have any effect in any sense.

Also, the study did not obtain evidence on whether calling the charge “price” or “tax” would have any different effect on the level of citizen support for the measure.

In summary, this study indicates that while the word used to name the CO2 tax has no impact on citizens’ favourable or unfavourable opinion, defining the destination of the funds raised does have a positive impact, and more so if the funds raised are used to reduce other taxes.

The results show that the most important factor for explaining support for the policies studied is whether citizens perceive that they are effective. We can consider as secondary the other factors, in other words, the perception on own responsibility for taking action against climate change, the perceived capacity to change own behaviour, resistance to any kind of change, and the distance with which people view climate change. The effect that they may have, in any event, varies according to the policy studied.

Thus then, the results obtained in the second part of the research, relating to the introduction of a tax on CO2 , suggest that the use given to the funds collected through such a tax is an important factor in citizen support, to the point that we must take it into account in any debate about this kind of measure.

Therefore, people who are at the forefront of the design and execution of public policies should, first and foremost, focus on successfully communicating the expected effectiveness of any measures proposed. And as people have diverse reasons for giving their support to a measure – reasons that depend, furthermore, on whether they see themselves as affected by the measure or not – public administrators should define their target audience with precision and design strategies to activate the support of everyone, i.e. individuals directly affected and those unaffected alike.

Finally, in order to better invest the resources available and gain maximum support from the general public, governmental authorities should adapt this strategy to the specific characteristics of every measure that it is necessary to implement.

El País (2019): "El 59% de los españoles pide medidas “muy urgentes” contra el calentamiento", El País, 8 December 2019.

IPPC (2018): Global warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty ​​​.

MORENO RODRÍGUEZ, J.M. (coord.) (2005): Evaluación preliminar de los impactos en España por efecto del cambio climático (Madrid: Ministerio de Medio Ambiente).

NASA (2019): Climate change: how do we know?