What Drove Fossil CO2 from 1990 to 2024? An Exact Kaya Decomposition for the World, India, China, the United States and the European Union

World fossil CO2 emissions rose from 22,732 Mt in 1990 to 38,599 Mt in 2024. I split the change into four drivers of the Kaya identity, population, GDP per head, energy per unit of GDP and CO2 per unit of energy, with the logarithmic-mean Divisia index (LMDI-I), using Our World in Data (Global Carbon Budget, Energy Institute) emissions and energy, and World Bank GDP at constant 2021 PPP prices and population. I prove that LMDI-I adds up exactly, and that the one-factor-at-a-time Laspeyres method does not; on the world data the Laspeyres residual is minus 6,573 Mt, equal to 41% of the change it is meant to explain. Of the world increase of 15,866 Mt, income growth contributed 19,194 Mt and population 12,868 Mt; falling energy intensity removed 13,727 Mt, and cleaner energy removed only 2,469 Mt. In India, emissions rose from 578 to 3,194 Mt, and the carbon content of energy rose rather than fell (plus 175 Mt). Between 2010 and 2024, 52 of 191 countries grew GDP while cutting CO2, together holding 42.2% of 2010 emissions. For India, 2019 to 2024 GDP grew at 4.89% a year in log terms while CO2 per unit of GDP fell at only 0.86% a year; emissions will keep rising until that gap closes.