Ideally, a country’s fair share would be proportional to its capacity to act. But ”capacity to act” isn’t easy to measure. We can approximate it with national income, which is often closely correlated to historical responsibility. Importantly, we take inequality within countries into explicit account when estimating national capacity. The income of those making just enough to scrape by cannot be considered part of some kind of national capacity for climate action. The responsibility for climate action lies primarily on the rich, not the poor.