Chaopeng Hong, Philippe Ciais, Zhu Liu, Olivier Boucher, Wenli Zhao, Pierre Gentine , Yilong Wang, Zhu Deng, Steven J Davis

As the ambition and urgency of climate mitigation efforts across the U.S. increase, annual estimates of national CO2 emissions provide only vague and outdated information about changes and progress. Using near-real-time activity data compiled from numerous sources, here we present and analyze daily, state-level estimates of fossil fuel CO2 emissions from January 2019 through December 2020. Our results quantify the abrupt but temporary decreases in emissions due to the COVID-19 pandemic (particularly related to transportation in April and May of 2020), but also reveal substantial variations across states according to the stringency of their public health responses. We also find that decreases in commercial demand for natural gas and electricity were partially but not fully offset by increases in residential demands in most places. Further, the carbon intensity of electricity and the share of electricity from coal decreased in many states in the first half of 2020 as compared to 2019, but then rebounded in the second half of 2020 when natural gas prices increased. In the future, as COVID-related restrictions dissipate and energy infrastructure evolves, our data and methods will allow state policymakers and energy analysts to closely monitor emissions trends, decarbonization progress and more quickly adjust policies and programs.