Dissertation Defense: Candelaria Bergero

Title: Carbon dioxide removals in net-zero emissions scenarios

Abstract: Since the industrial era, human activities have caused a 0.99°C increase in global mean temperatures, primarily by increasing the amount of greenhouse gases in the atmosphere. Without mitigating these emissions, global warming could exceed 4°C by 2100, while current mitigation policies place us on track for 2.2–3.5 °C. To stabilize climate and limit warming to well-below 2°C, as established in the Paris Agreement, net-zero emission emissions targets are essential. Achieving net-zero requires not only reducing emission but also deploying carbon dioxide removal (CDR) to offset residual emissions and legacy emissions. While net-zero targets are a scientific concept, achieving these targets entails complex social, political, and economic implications. The goal of this dissertation is to advance our understanding of these implications, and to challenge prevailing assumptions about what net-zero means in practice—especially as it relates to removing carbon from the atmosphere. We thus analyze CDR deployment in the context of achieving net-zero emissions from the hard-to-abate aviation sector (Chapter 1), we study how CDR deployment could affect environmental justice in net-zero emission targets in the United States (Chapter 2), and we quantify the climate risks associated with failing to deliver future carbon management (Chapter 3). We conclude that while CDR technologies will likely be necessary to achieve ambitious climate goals, they should remain secondary to emission reductions. Importantly, the social, political, and economic implications of deploying such technologies must be carefully evaluated to ensure that mitigation efforts are both feasible and just.