Biennial update reports (BURs) are a core requirement of the United Nations Framework Convention on Climate Change (UNFCCC). However, many non-Annex I countries have not submitted these reports due to inventory difficulties. We have developed a satellite-based method for inversely estimating CO emissions ₂ top-down using partial column data in the lower troposphere obtained by a greenhouse gas observing satellite, which was adopted to verify the Mongolian 2. ^BUR (BUR2) for the energy sector. in 2018. Estimated CO ₂emissions were only 1.5 % higher than those reported in BUR2; these were also very close (4.2 % lower) to estimates from the Global Atmosphere Research Emissions Database. Mongolia is the first country to introduce an independent inverse estimate in its BUR, thereby increasing scientific transparency. Our method could be used in other countries and could be incorporated into the UNFCCC reporting guidelines, significantly improving estimates of global CO emissions. _{2 . (Masataka Watanabe)}