wealth, emissions, billionaires, ownership, carbon tax, wealth tax, carbon wealth tax

D3, D63, G32, Q50, Q54

How large are billionaires' carbon footprints? While increasing evidence highlights large disparities in emissions between and within countries, detailed individual-level data on emissions portfolios remain scarce. In this paper, we analyze the wealth composition of the top 501 billionaires and construct a dataset linking each of their assets to emissions. According to our ownership-based emission accounting framework, every USD million held by billionaires is associated with more than 65 tCO2e per year -about 10 times the annual carbon footprint of the average person. Further, our estimates reveal an extreme concentration of wealth among the super-rich and, even more so, emissions. About 50 billionaires account for nearly three-quarters of total emissions in our sample, with publicly traded equity in Basic Materials, Industrials, and Utilities playing a disproportionate role as emission sources. Emission intensity is key: 97% of the variance in log emissions is explained by intensity differences, suggesting that scale effects play a limited role and carbon footprints are almost entirely driven by investment choices. The highest-emitting billionaires -including some of the wealthiest- derive a substantial share of their emissions (between 44 and 66%) from hard-to-abate sectors. Comparing alternative taxation schemes targeting both extreme wealth and emissions, we show that the introduction of a new progressive carbon wealth tax can potentially achieve three objectives: progressively taxing billionaires to curb inequality, targeting the most polluting activities, and raising substantial resources to finance a sustainable and equitable transition.