Mobilizing Climate Change Legislation in Brazil

Last registered on June 22, 2026
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Pre-Trial

Trial Information

General Information

Title
Mobilizing Climate Change Legislation in Brazil
RCT ID
AEARCTR-0018580
Initial registration date
June 15, 2026

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
June 22, 2026, 6:39 AM EDT

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

Locations

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Primary Investigator

Name
Frederico Finan
Affiliation
UC-Berkeley
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Other Primary Investigator(s)

PI Name
Amanda de Albuquerque
PI Affiliation
Rede A Ponte
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PI Name
Ernesto Dal Bó
PI Affiliation
UC Berkeley
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PI Name
Clarissa Gandour
PI Affiliation
FGV
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Additional Trial Information

Status
On going
Start date
2026-01-12
End date
2026-12-14
Keywords
Agriculture, Environment & Energy, Governance
Additional Keywords
JEL code(s)
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
This project tests strategies to accelerate municipal climate legislation in Brazil. Through a two-stage, cross-randomized field experiment across 2,500 municipalities, researchers will evaluate how message framing and citizen mobilization influence legislators’ willingness to introduce and approve a ready-to-pass bill about adaptation to climate change.
External Link(s)

Registration Citation

Citation
Dal Bó, Ernesto et al. 2026. "Mobilizing Climate Change Legislation in Brazil." AEA RCT Registry. June 22. https://doi.org/10.1257/rct.18580-1.0
Sponsors & Partners

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Experimental Details

Interventions

Intervention(s)
In our first wave of outreach, legislators in treatment municipalities will receive geotargeted online outreach announcing a bill with one of two different framings, with visuals and text tailored to the assigned framing. Legislators’ online accounts will be tagged in the captions to increase visibility and peer recognition. The content of the bill itself remains constant across groups, only the narrative framing differs.

A second wave of outreach will be launched for citizens within targeted municipalities. Within each treatment group from Stage 1, half of the municipalities (500 framing A + 500 framing B) will be randomly assigned to receive a new, targeted online campaign directed at citizens. The messages will use neutral, factual language and encourage citizens to learn about the initiative and, if they wish, contact their local legislators to advocate for the bill’s introduction and approval. Messages will be geo-targeted to residents within each municipality, ensuring precision and minimizing spillovers.
Intervention Start Date
2026-03-02
Intervention End Date
2026-06-30

Primary Outcomes

Primary Outcomes (end points)
- Legislator engagement: open and response rates to messages; number of legislators completing an online interest form.
- Public engagement: impressions, clicks, and interactions with online messages.
- Legislative action: number of bills introduced and approved; voting behavior on climate-related legislation.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
Our study utilizes a cross-randomization design, allowing us to learn how to optimize the targeting of the audience and which messages lead to greater policy action. We propose a factorial design with 5 treatment groups, randomized at the municipality level, which will allow us to learn about the interaction between message framing and targeting.
Experimental Design Details
Not available
Randomization Method
Randomization done via computer
Randomization Unit
municipality
Was the treatment clustered?
Yes

Experiment Characteristics

Sample size: planned number of clusters
2500 municipalities
Sample size: planned number of observations
2500 municipalities
Sample size (or number of clusters) by treatment arms
500 municipalities control, 500 municipalities framing A with citizen mobilization, 500 municipalities framing A without citizen mobilization, 500 municipalities framing B with citizen mobilization, 500 municipalities framing B without citizen mobilization
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Supporting Documents and Materials
IRB

Institutional Review Boards (IRBs)

IRB Name
Heartland IRB
IRB Approval Date
2025-09-23
IRB Approval Number
092325-1250
Analysis Plan