Accepted for/Published in: Journal of Medical Internet Research
Date Submitted: Aug 14, 2025
Date Accepted: Oct 28, 2025
(closed for review but you can still tweet)
Warning: This is an author submission that is not peer-reviewed or edited. Preprints - unless they show as "accepted" - should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
Exploring Reddit for public discourse and information needs surrounding extreme heat in Canada: Mixed Methods Study
ABSTRACT
Background:
As Canada’s climate changes, extreme heat events have become more frequent, a trend that is expected to continue. Extreme heat can lead to several negative health outcomes, which disproportionately impact vulnerable populations. Evidence-based, equitable interventions are needed to inform and protect the public from the health effects. Effective communication can aid this effort to improve health outcomes by emphasizing the connection between health risks and climate change and empowering people to act. Machine learning has applications in understanding current attitudes, beliefs, experiences, and behaviours within the target audience for public health messaging. Machine learning analyses of social media data have elucidated user perceptions of heat events in the literature; however, research is limited with respect to social media user perceptions, beliefs, and behaviours related to extreme heat, particularly in the Canadian context. Analyzing Canadian social media discourse related to extreme heat will help to address this research gap and inform future research and communications to reduce the risks of extreme heat.
Objective:
The purpose of this research is to better understand Canadian discourse and emotions related to extreme heat by examining social media (Reddit). Our objectives include: 1) Identifying common discussion topics, concerns, and questions related to extreme heat among Canadian Reddit users; 2) Analyzing sentiment and emotional responses to extreme heat discussions; 3) Investigating the relationship between topics, sentiment, and engagement for posts.
Methods:
We collected data using the Reddit API, retrieving posts from 30 Canada-specific subreddits between February 12, 2023, and February 11, 2024, based on a predefined set of heat- and climate-related keywords. Posts and comments were structured as hierarchical tree models, with text consolidated into documents for analysis. Topic modelling, sentiment analysis, and emotion analysis were conducted; engagement was assessed using net upvote scores to gauge community approval.
Results:
The analysis of 607 Reddit posts from over 15,000 users revealed that discussions about extreme heat were most frequently centred around the keyword "heat," which appeared in 82.5% of posts and 81.1% of comments. Topic analysis identified key themes related to heating and cooling costs, weather records, air conditioning, and taxation, while sentiment and emotion analyses showed varying levels of positivity and negativity across subreddits.
Conclusions:
Our findings present an initial snapshot into Canadian perspectives and information needs about extreme heat in Canada. Discussions on Reddit about extreme heat in Canada are dominated by concerns over heating and cooling costs, weather patterns, and personal adaptation strategies, reflecting both practical and policy-related challenges. Additionally, sentiment and emotion analyses suggest significant regional differences in public perception, which may be useful for informing health and risk messaging initiatives to better protect Canadians from the adverse health effects of climate change.
Citation
