Natural gas and spillover from the US Clean Power Plan into the Paris Agreement

Climate change has been identified as one of the today's great challenges, and mitigation likely requires policy intervention. As such, in 2015 the United States introduced the Clean Power Plan (CPP) which aims to reduce CO2 emissions from electricity production 32% from 2005 levels by 2030 and the Paris Agreement, which seeks to reduce national greenhouse gas (GHG) emissions, measured by global warming potential (GWP), 28% from 2005 levels by 2025. However, it remains unknown how the more narrowly-scoped CPP might affect the ability to achieve wider-scoped national GHG targets like the Paris Agreement. In our current state-of-world, characterized by inexpensive natural gas, the CPP will be met through large shifts from high-emitting coal power to less-emitting natural gas power, which translates to a 9.6% reduction in total US 100-year GWP without accounting for the fugitive methane. Spillover from fugitive methane could cut this reduction modestly by 0.2–1.4% or as much as 4.4% if evaluated using 20-year GWP – elucidating how different assumptions leads to different perspectives of natural gas as a "bridge fuel". The results here demonstrate the need to coordinate policies – either through additional policy (e.g. regulation of fugitive methane) or a larger-scoped CPP that includes upstream activities.