Location
MC 6460
Candidate
Amrita Punnavajhala | Applied Mathematics, University of Waterloo
Title
Introducing heterogeneity into coupled social-climate models
Abstract
Anthropogenic climate change is possibly the greatest global problem we face today. However efforts to mitigate climate change are insufficient to keep warming within the safe limit of 1.5 degrees Celsius, despite the increasing availability and affordability of clean energy. Resistance to mitigation arises from social and geopolitical factors. However the role of social dynamics in mitigation is not well understood as these have been treated as extrinsic to most existing models of climate change. Recently coupled social-climate models have modeled two-way feedback between social systems and climate change and found social parameters to be comparable to geophysical parameters in their influence of climate change outcomes. However, most of these models assume society to be homogeneous or contain stylized representations of heterogeneity. In this thesis, we construct a coupled social-climate model representing five world regions, parameterized with empirical survey and socioeconomic data, and use evolutionary game theory to model the evolution of mitigation support in each region. We find that social learning and norms can cause mitigation support to collapse or spread, and that opinions in one region are affected by opinions in other parts of the world, purely through feedback from the global warming. Social processes influence the peak temperature anomaly by several degrees Celsius. We next look at the roles of social and climate change impact heterogeneity in shaping social-climate outcomes by including location-specific warming and vulnerability to impacts in our model. We find that heterogeneity, on the whole, leads to worse global warming outcomes, with heterogeneity in impacts increasing the peak temperature by 0.2 degrees Celsius. We also identify bistable social-climate outcomes, and find that a drop in vulnerability to impacts in one region can tip the social-climate system into a slow-mitigation, high-temperature outcome. Finally, we couple our model of social-climate dynamics to a game theoretical representation of government decision-making on climate change mitigation. We find that if governments factor in support for mitigation evolving over time, it could lead to more or fewer regions choosing to mitigate at Nash equilibria, depending on mitigation targets considered. Social processes alone cannot create conditions for a coordination game as long as regions are coupled through temperature impacts alone. This thesis presents a framework for representing heterogeneity in coupled social-climate models, identifies states that do not arise in homogenous settings and, therefore, provides insight into ways to overcome social barriers to mitigation.