Dissertations, Theses, and Capstone Projects

Date of Degree

6-2026

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy

Program

Political Science

Advisor

David Jones

Committee Members

Charles Tien

Keena Lipsitz

Till Weber

Jeffrey Ladewig

Subject Categories

American Politics | Environmental Policy | Political Science | Social and Behavioral Sciences

Keywords

climate change, Congress, political parties, political polarization, member replacement, roll-call voting

Abstract

Scholars offer competing explanations for how congressional polarization develops and operates. The literature variously points to shifting agendas, procedural change, or member adaptation or replacement. In this project, I study how congressional polarization occurs by asking what mechanisms account for the emergence of climate policy polarization. Climate policy is a useful test case to evaluate these competing theories. As a relatively low-salience, highly technical issue that is neither new nor inherently ideological, it is not an obvious candidate for deep partisan division. Yet climate policy has become sharply polarized, extending partisan disagreement even to the underlying science.

In order to study this phenomenon, I constructed an original dataset of all 314 climate-related roll-call votes cast in Congress from 1973 to 2016 and calculated member climate scores. I employ multiple quantitative methods—including analyses of voting patterns and an original “adaptation-only” counterfactual Congress—to assess the mechanisms of climate polarization in Congress. I supplement these tests with critical discourse analysis of select case studies to examine why these mechanisms operate. I argue that congressional polarization on climate policy is an ongoing process driven by the replacement of moderate and misaligned Members of Congress with party-aligned extremists, and I show that neither widespread member adaptation nor agenda change or control alone accounts for climate polarization. Additionally, I demonstrate that replacement occurs through multiple pathways that form an elite-driven feedback loop, serving to further strengthen congressional polarization. By isolating polarization within a single policy domain, this study clarifies the mechanisms through which polarization manifests in Congress and demonstrates the value of sustained, issue-specific analysis for understanding polarization more broadly.

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