This is partly because rich nations already have a lot of capital and technology, which will help them decarbonize their economies more quickly. What’s more, their populations are barely growing.
The population of poorer nations outside the OECD, by contrast, will grow by 1.5 billion people over the period, according to the EIA baseline projection. These people will aspire to higher living standards than their forebears. Improving living standards, everywhere and always throughout human history, has required consuming more energy. That’s where most of the CO2 emissions will come from.
The growth of CO2 emissions can be decomposed into the product of changes in population, GDP per person, the amount of energy needed to produce GDP and the amount of carbon emitted for each unit of energy used.