The effect of climate news on climate policy support

Last registered on February 08, 2024


Trial Information

General Information

The effect of climate news on climate policy support
Initial registration date
January 25, 2024

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
January 31, 2024, 11:45 AM EST

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

Last updated
February 08, 2024, 5:25 AM EST

Last updated is the most recent time when changes to the trial's registration were published.



Primary Investigator

University of Hamburg

Other Primary Investigator(s)

PI Affiliation
Univesity of Hamburg
PI Affiliation
Univesity of Hamburg
PI Affiliation
Univesity of Hamburg
PI Affiliation
Univesity of Hamburg

Additional Trial Information

Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
How does scientific news about natural and social dimensions of climate science affect support for climate policy in the general population? We study this fundamental question with a large-scale survey experiment that exposes 8000 members from the general population in Germany to good and bad news about climate science, next to control treatments that contain no information or information but no good or bad news. Specifically, we consider news on the magnitude of equilibrium climate sensitivity, on the effectiveness of climate policy instruments, and on the plausibility of reaching the Paris temperature targets. We also examine the emotions evoked by different kinds of news and the effect of those emotions on support for climate policy.
External Link(s)

Registration Citation

Damania, Mrunali et al. 2024. "The effect of climate news on climate policy support." AEA RCT Registry. February 08.
Experimental Details


We run online surveys in Germany. We recruit participants through a professional survey company (Bilendi). To be eligible subjects must be adults (age 18+). The sample will use quotas for age brackets, gender and eduction (with and without a highschool diploma 'Abitur') to match the distribution in the general population.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Pre-treatment attitudes towards climate change and trust in climate scientists (we distinguish between those researching the natural phenomenon of climate change and those researching climate policy).
Post-treatment hypothetical support for specific climate policies (ban of combustion engine cares, level of domestic carbon price in 2025, and year by which Germany should be carbon neutral). Participants are informed that summary statistics of these questions will be forwarded to the committee of the Federal Parliament (Bundestag) responsible for climate policy.
Post-treatment consequential choices (donation to WWF and vote for the purchase of permanent retirement of emission rights)
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
To identify channels of transmission, we measure the extent to which participants perceive information as good or bad news and the emotions invoked when reading the information.
We are also interested in the heterogeneity of the background characteristics of respondents and will thus look at outcomes by sub-groups as defined by income, age, gender, political affiliation, education level and employment status.
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
All subjects answers questions about demographics and prior beliefs and attitudes towards climate change, climate policy and climate science.
In the treatment groups, subjects receive a "good” or “bad” news from climate science on (i) climate sensitivity, (ii) effectiveness of climate policies or (iii) plausibility of temperature targets.
Those subjects receiving information also indicate whether they perceive the news as "positive" or "negative", how they feel when they read the news and they are asked to write down briefly how they would explain the news to a friend.
There are two control groups. One control group does not receive any additional information, the other receive some climate information without reference to the future and without a clear positive or negative connotation.
All subjects then answer questions about their support for specific climate policies (ban on new cars running on gasoline or diesel, the preferred level of the domestic carbon price in Germany in 2025, and the preferred date of carbon neutrality in Germany) as well as questions about their family composition, income and political attutudes.
Respondents make two decisions that have real consequences.
First, they are informed that they have been automatically enrolled in a lottery to win 10 euors. The probability of winning is one in ten. Before they know whether they have won or not, they need to commit to donating none of it, part of it, or all of it to the climate campaign of the WWF (World Wide Fund for Nature). We use the amount respondents wish to donate as (real) measure of support for action to mitigate climate change.
Second, subjects within each treatment vote on whether they will collectively contribute to reducing greenhouse gas emissions by 10 tons of CO2. The reduction in emissions is achieved through the purchase and permanent retirement of emission rights worth 10 tons of CO2 from the European Union Emissions Trading System. The purchase and retirement of emission rights is carried out by the non-profit organization ForTomorrow. If the majority of participants vote in favor of the purchase and retirement of emission allowances, the proposal is implemented. In this case, all participants in the survey receive a copy of the certificate confirming that 10 emission allowances have been definitively retired. However, if the majority of participants vote against the purchase and retirement of emission allowances, no emission allowances are retired and all participants are credited with additional panel points worth 1 euro.
Experimental Design Details

Hp1: Providing ``bad (good) news'' about climate change/policy strengthens (weakens) support for ambitious climate policies.

Hp2: Participants with a higher trust in the respective branch of climate science (elicited ex ante) respond more to treatments.

Hp3: The clearer participants attribute information to the good/bad news categories, and the stronger their emotional response, the stronger are treatment effects.
Randomization Method
The randomization into treatments is done by the survey company.
The randomization of winners of the lottery (one of the primary outcome variables) is done by the researchers after completion of data collection.
Randomization Unit
We randomize individual participants in two control and six treatment groups. All groups have the same a priori probability.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
1 country, Germany
Sample size: planned number of observations
8,000 individuals
Sample size (or number of clusters) by treatment arms
1,000 individuals for each experimental condition (two control and six treatment conditions)
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials

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Institutional Review Boards (IRBs)

IRB Name
Ethics committee for the Faculty of Business, Economics and Social Sciences at Universität Hamburg
IRB Approval Date
IRB Approval Number


Post Trial Information

Study Withdrawal

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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