Climate-denying rumor propagation in a coupled socio-climate model: Impact on average global temperature

also provide deeper insights on various factors that helps in understanding how to mitigate the effects of rumors. But most of these models focus on individual rumor dynamics. There are very few models that address propagation of rumors in groups [49]. Individual rumor propa- gation occurs when an individual spreads rumors by sharing them with other individuals whereas, in group propagation, an individual propagates the rumor to an entire group of indi- viduals, such as via social media. Various aspects of group and individual rumor propagation have the power to affect individuals’ attitudes toward climate change. Most of the population has only a superficial knowledge of climate change [50]. Perhaps as a result, rumors about cli- mate change–especially climate misinformation–are common and there are empirical studies and statistical models that deal with myths and fake news regarding climate change [51, 52]. Several coupled models deal with climate change and various aspects of human behavior, integrating features such as imitation dynamics and social norms [27, 37]. However, previous coupled social-climate models have not included rumor propagation, despite the fact that rumours which deny climate change are a major reason for individuals and groups not acknowledging the urgency of the climate emergency, and thus not taking effective mitigation strategies [53, 54]. Here, a coupled socio-climate model is developed where rumor propagation spreads through a mathematical approximation of a social network. Our objective is to dem-

onstrate a simple yet novel way of modeling interactions between rumor spread as an conta- gious processes and long-term climate dynamics to gain insights into potential social-climate dynamics. A simple Earth system model is used to capture temporal dynamics of the global temperature anomaly, and our rumor propagation model is correspondingly simple. Although social-climate systems are complex, starting with a simple model can be useful to illustrate concepts, discover new dynamical regimes, and suggest a framework for future, more sophisti- cated social-climate models. 2 Methods A mathematical model linking climate-denying rumor propagation (including group dynam- ics) in heterogeneous networks with climate dynamics is proposed. The coupled rumor-cli- mate change model is proposed by adding the climate dynamics into an existing rumor propagation model [49] in social networks by relating the human responses to rumors based on the range of climate change they experience. In this extension, the rumors are assumed to be false information about climate change. The model is developed by coupling the rumor- spreading model with an Earth System Model (ESM) to analyze the dynamics of the coupled system, in which the rumor propagation about climate change begins in 2021. The model con- siders a heterogeneous rumor model since real-life networks, including social networking sites, are heterogeneous in nature. This is done by incorporating emissions (mainly CO2, an important greenhouse gas) and temperature into the model. The rumor model has two com-

ponents: individual propagation and group propagation. The model helps us interpret how the parameters involved in rumor propagation influence emission levels and temperature change and how changes in temperature levels influence human attitude towards the rumors about climate change. The rumor-climate change dynamics are formulated such that when individu- als understand that the rumors are false, they try to mitigate climate change (S1 Fig). Similarly, individuals who experience climate change, through changes in temperature, believe that the rumors are not true. 2.1 Rumor propagation model An existing rumor propagation model involving group propagation in heterogeneous net- works is used [49]. Each node represents either an individual or a group in the social network, PLOS ONE Climate-denying rumor propagation in a coupled socio-climate model: Impact on average global temperature PLOS ONE | https://doi.org/10.1371/journal.pone.0317338 January 16, 2025 3 / 18