Resumen de Preu de l'carboni i interaccions socials: implicacions per al disseny de polítiques climàtiques
Mitigating climate change is one of the greatest challenges of our time. Our economies should attain net zero emissions by the middle of the century to avoid catastrophic damages.
Following the Paris Agreement in 2015, the European Union and many national governments have pledged to reach carbon neutrality by 2050. However, current commitments fall short of the mitigation objective.This underpins the urgency of implementing effective policies to decrease greenhouse gas emissions.
Climate policy does not happen in a societal and political vacuum. One of the shortcomings of conventional models in climate economics is that they ignore the social environment in which agents interact. I argue in this thesis that a good understanding of the social context surrounding climate policies is essential for designing efficient and acceptable instruments.
I make use of agent-based models (ABMs) to integrate specific aspects of social interactions into a climate-economic framework. ABMs are flexible models that allow to depart from traditional assumptions about representative and socially isolated agents, namely by describing a population of heterogeneous agents with a wide range of possible behaviours and interactions.
The second chapter, entitled “Social reinforcement with weighted interactions”, studies the diffusion of low-carbon behaviors in social networks. It introduces several new features, such as confirmation bias, which is the tendency to put more weight on opinions that confirm one’s prior beliefs, and a network topology pervasive in online social networks. The results show that under realistic assumptions regarding agents' interactions, network degree distribution is the key factor for fast and widespread low-carbon behavior adoption.
The third chapter, entitled “The Social Multiplier of Environmental Policy: Application to Carbon Taxation”, analyzes the effectiveness of carbon taxation when consumers are subject to social influence. It introduces socially-embedded preferences formed under the influence of peers and derives a so-called social multiplier of environmental policy. The approach provides a basis for rigorously analyzing a transition to low-carbon lifestyles and identifying complementary information and network policies to complement and reinforce the effectiveness of carbon taxation.
The fourth chapter, entitled “Optimal trajectory of carbon taxation under endogenous preferences”, is the logical continuation of the previous one. It derives optimal dynamics of a carbon tax when preferences are endogenous, i.e. when the tax modifies the formation of preferences of agents. In particular, the study focuses on the conditions under which the optimal tax is decreasing.
The fifth chapter, entitled “Co-dynamics of climate policy stringency and public support”, studies the design of intertemporal climate policy that is effective in meeting climate targets as well as receives support from a majority of voters. To this end, it combines a general equilibrium model for impact assessment of climate policy with an agent-based model involving a social network for assessing public opinion dynamics, and study the political feasibility of several climate policies. The results show that a tax characterized by an initially low rate which increases over time, combined with progressive revenue redistribution, generates critical public support.
