Climate Change

In this paper, we adopt a novel approach to integrate political-organizational and techno-economic considerations to analyze decarbonization pathways for the United States. To do so, we first construct three portfolios of granular policies that target greenhouse gas (GHG) emissions reductions in the electricity, transportation, and buildings sectors, which we deem politically feasible under different federal political contexts. We then implement sectoral policy portfolios in the US-TIMES model and compare them to a business-as-usual (BAU) scenario and an 80% system-wide decarbonization scenario that uses stylized emissions constraints to produce the least-cost decarbonization pathway. Our findings reveal that greater political alignment enables electrification to play a more significant role as a central component of decarbonization. Renewable electricity generation and light-duty vehicle electrification both expand. Moreover, if the political environment allows more ambitious climate policies, deeper decarbonization can actually be achieved at a lower average abatement cost because more economically efficient policy instruments become politically feasible. However, our results indicate that none of our sectoral policy portfolios is sufficient to reduce system-wide GHG emissions by 80% by 2050. Major emissions sources for which new technologies and policies will be needed include heavy-duty vehicles, aviation, industrial production, and natural gas use in buildings.

Debates about the decentralization of environmental policy are important and are far from resolved (1, 2). Interregional spillovers provide one key justification for centralized regulation: When regulation is decentralized, individual jurisdictions may not protect downstream or downwind neighbors from their pollution (2, 3). Under the Trump administration, the U.S. Environmental Protection Agency (EPA) and U.S. Army Corps of Engineers (ACE) departed from precedent to support the deregulation of U.S. waterways in the repeal of the 2015 Clean Water Rule (CWR) and its replacement with the 2020 Navigable Waters Protection Rule (NWPR). In doing so, they assumed (with little evidence) that many states would fill gaps in federal oversight. With the Biden administration having signaled its intent to modernize regulatory review and to review specific deregulatory actions taken by the Trump administration, we describe here how this environmental federalism approach downplays the importance of cross-state pollution and relies on flawed methods of benefit-cost analysis that could be used to weaken other statutes.