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<p>Existing <span class="inline-formula">CO₂</span> emissions reported by city inventories usually lag in real-time by a year or more and are prone to large uncertainties. This study responds to the growing need for timely and precise estimation of urban <span class="inline-formula">CO₂</span> emissions to support present and future mitigation measures and policies. We focus on the Paris metropolitan area, the largest urban region in the European Union and the city with the densest atmospheric <span class="inline-formula">CO₂</span> observation network in Europe. We performed long-term atmospheric inversions to quantify the citywide <span class="inline-formula">CO₂</span> emissions, i.e., fossil fuel as well as biogenic sources and sinks, over 6 years (2016–2021) using a Bayesian inverse modeling system. Our inversion framework benefits from a novel near-real-time hourly fossil fuel <span class="inline-formula">CO₂</span> emission inventory (Origins.earth) at 1 km spatial resolution. In addition to the mid-afternoon observations, we attempt to assimilate morning <span class="inline-formula">CO₂</span> concentrations based on the ability of the Weather Research and Forecasting model with Chemistry (WRF-Chem) transport model to simulate atmospheric boundary layer dynamics constrained by observed layer heights. Our results show a long-term decreasing trend of around 2 % <span class="inline-formula">±</span> 0.6 % per year in annual <span class="inline-formula">CO₂</span> emissions over the Paris region. The impact of the COVID-19 pandemic led to a 13 % <span class="inline-formula">±</span> 1 % reduction in annual fossil fuel <span class="inline-formula">CO₂</span> emissions in 2020 with respect to 2019. Subsequently, annual emissions increased by 5.2 % <span class="inline-formula">±</span> 14.2 % from 32.6 <span class="inline-formula">±</span> 2.2 <span class="inline-formula">Mt CO₂</span> in 2020 to 34.3 <span class="inline-formula">±</span> 2.3 <span class="inline-formula">Mt CO₂</span> in 2021. Based on a combination of up-to-date inventories, high-resolution atmospheric modeling and high-precision observations, our current capacity can deliver near-real-time <span class="inline-formula">CO₂</span> emission estimates at the city scale in less than a month, and the results agree within 10 % with independent estimates from multiple city-scale inventories.</p>