Do Municipal Climate Protection Activities Interfere with Individual Engagement

Last registered on November 25, 2020


Trial Information

General Information

Do Municipal Climate Protection Activities Interfere with Individual Engagement
Initial registration date
November 23, 2020

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
November 25, 2020, 10:36 AM EST

First published corresponds to when the trial was first made public on the Registry after being reviewed.



Primary Investigator

ZEW – Leibniz Centre for European Economic Research

Other Primary Investigator(s)

PI Affiliation
ZEW - Leibniz Centre for European Economic Research

Additional Trial Information

On going
Start date
End date
Secondary IDs
The Paris Agreement aims at limiting the global average temperature increase to well below 2°C above preindustrial levels. A key component of the agreement are “nationally determined contributions” (NDC). For this, non-state actors such as civil society groups, economic actors, and subnational and local actors (e.g. Municipalities) play a decisive role. They can either directly reduce greenhouse gas emissions by additional voluntary activities, or indirectly by influencing the climate protection activities of individual actors. However, a successful integration of non-state actors must happen within the larger framework of the global climate regime. Literature (Johnson, Schroeder, and Toly 2015; Ostrom 2010; Romero-Lankao and Hardoy 201; Janicke and Quitzow, 2017) has already stressed the importance of a “polycentric” or multi‐level climate governance as an enabler for a transformation climate governance. As the role of non-state actors within reaching the climate goals has received little attention within research, our research focuses on the lowest rungs of the multi‐level climate governance ladder and analyses feedback loops between local non-state actors, here municipalities, and individual climate protection activities. With a framed-field experiment we aim to analyze the relationship between individual commitment to climate protection and the commitment of other fellow citizens, and the interaction between individual commitment and municipal engagement. Special attention is paid on potential crowding in or crowding out effects.
External Link(s)

Registration Citation

Bartels, Lara and Martin Kesternich. 2020. "Do Municipal Climate Protection Activities Interfere with Individual Engagement." AEA RCT Registry. November 25.
Experimental Details


The aim of the experiment is to investigate the relationships between non-state and individual actors. More precisely, the interaction between individual climate protection contributions and municipal engagement will be investigated on two levels: i. the relationship between individual commitment to climate protection and the commitment of other fellow citizens, and ii. the interaction between individual commitment and municipal engagement. Special attention is paid on potential crowding in or crowding out effects.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
As primary outcome measures, we analyze the willingness to contribute to a local forest carbon sink / sequestration project in form of a donation decision. We will investigate both extensive margin (i.e. share of donors) and intensive margin (i.e. amount of money donated) effects and investigate the impact of giving a reference values of fellow citizens, of the fellow municipality, and none.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
The procedure of the experiment is as follows: Participants were invited to answer a survey thematically unrelated to the experiment on the topic of the General Data Protection Regulation (GDPR). The LimeSurvey software was used to implement the online questionnaire and to generate personalized token to access the survey. The links were distributed to the participants via e-mail and direct mail. In the invitation email, participants were informed about the general content of the survey (General Data Protection Regulation GDPR), their fixed payment of 15 € for complete participation, and that payments were disbursed using PayPal.
After completing the online survey, participants were, for the first time, confronted with the opportunity to donate their fixed payment earned in the survey (15€) to support additional tree planting within an existing tree planting project. Before being able to make a donation, participants of all treatments received the same information about the need to protect our climate, the Parisian climate goals, and the role of trees as carbon sinks.
Unknown to the potential donors, subjects were then randomly allocated to one out of the three treatments, which vary a given reference value. In the first treatment T1, the basic treatment, the donation decision is framed in a neutral manner without giving any reference values. The mean willingness to donate of T1 are then used as reference value for the second treatment T2. Thus, T2 provides a reference value on the mean climate protection activities of other fellow citizens. Similarly, a reference value for municipal climate protection commitment is provided in T3.
The first intervention – our baseline treatment –took place from 19th to 4th November 2020, there no reference values were introduced. Based on the baseline treatment, we identify the reference values based on the mean donation for our second treatment – the Citizen Treatment. The third treatment – the City Treatment – gives a reference value based on a city initiative. The second and third treatment are run in parallel from the 16th to 1st December.
Experimental Design Details
The selected reforestation project is part of the Bundesgartenschau (Federal Horticultural Show) in 2023. The City of Mannheim has been selected to host the Bundesgartenschau in 2023. The Bundesgartenschau is a German exhibition on horticulture which also included topics such as landscape architecture. In its current form, it traces back to 1951 and takes place every two years in various German cities, and every ten years as the International Horticultural Exhibition. In 2019, the Federal Horticultural Show took place in Heilbronn and attracted a total of around 2.3 million visitors on the 173 open days (Statista, 2019). As part of the preparations for the upcoming event, the City of Mannheim plans to unseal urban areas and create an additional local carbon sink by permanently planting about 500 trees. Participants were informed that they were able to donate to the planting of additional trees within the BuGa2023. With the collected donations, additional trees will be planted on the BuGa2023 site in addition to those already planned.
Randomization Method
Participants will on the one hand be randomly selected from an existing database for experimental studies using a computer based random number generator mechanism. On the other hand, new participants are recruited by randomly distributed direct mail. By recruiting new participants to the existing database, it is kept active and diverse for future interventions.
Randomization Unit
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
The treatments are not clustered.
Sample size: planned number of observations
In total, we plan to collect 450 donation observations.
Sample size (or number of clusters) by treatment arms
Participants are randomly allocated to the treatments, with an equal weighting of the treatments. Each treatment is planned to have 150 observations.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
IRB Approval Date
IRB Approval Number


Post Trial Information

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials