Before revision:  We use Gaussian process (GP) regression to assess whether CO_2 emissions reductions would have occurred with reasonable probability in the absence of COVID-19 considering uncertainty due to factors unrelated to the pandemic . We show that CO_2 emissions are lower than levels expected in the absence of COVID-19 for each month from March through July 2020 but that those monthly reductions are not statistically significant considering hypothesis tests at 5\% significance levels.
After revision:  We use Gaussian process (GP) regression to assess whether CO_2 emissions reductions would have occurred with reasonable probability in the absence of COVID-19 considering uncertainty due to factors unrelated to the pandemic and adjusting for weather, seasonality, and recent emissions trends. We find that monthly CO2 emissions reductions are only statistically significant in April and May 2020 but that those monthly reductions are not statistically significant considering hypothesis tests at 5\% significance levels.