Carbon Monitor Cities, Near-Real-Time Monitoring of Daily Fossil-Fuel CO2 Emissions from Cities Worldwide
Urban areas generate more than half of fossil-fuel carbon dioxide (CO2) emissions worldwide, and many cities are in urgent need of near-real-time emission inventories to timely adjust climate policies and monitor mitigation progress. Unfortunately, such datasets are still lacking for most cities, and existing inventories are mostly at national scale and often lag reality by at least one year. City self-reported inventories also suffer from low reliability due to the lack of peer review. Here we present the Carbon Monitor Cities, a recently developed near-real-time CO2 emissions dataset that provides daily, city-level estimates of scope-1 CO2 emissions from 2019 through 2022 for over 1500 major cities worldwide. This dataset is developed based on an innovative workflow that combines a global harmonized top-down approach and local available bottom-up inventories for power, residential, industry, ground transportation, and aviation sectors. Carbon Monitor Cities reduces the time lag of city-level emission datasets to less than 6 months and estimates daily emissions which can help investigate high resolution urban activity-emission dynamics. We find that for most cities, emissions exhibited a significant drop in spring 2020 due to the COVID-19 pandemic, and rebounded in 2021. The daily emissions also highlight the heterogeneous sectoral and temporal responses to lockdowns and daily emission patterns that reveal a city’s geographic and socio-economic characteristics. We plan to frequently update this dataset and improve the workflow in the future to better facilitate urban climate policymaking.